OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Victa Two Stroke Engines Late Mode Victa 2 Stroke will not restart when Hot

Hi Guys,


First time Poster.


I am after assistance to fix my Late Model 2 Stroke Victa Lawn Mower.

To give you some information. I have replaced the Spark Plug. I have purchased a Victa Carby Kit and replaced the Diaphragm , Cutoff boot and O rings. I am still using the original Needle and springs.

The Poppet valve, is an A, 3, C type Poppet Valve and it is set to C. Without a Rev Meter, I am thinking it is revving at about 3000rpm, but I could be wrong.

When cold, I set the throttle just past the Cold start spot and pressing the primer bulb about 6 times it will usually start within 2 pulls and keep running until turned off.

Whilst running, it seems okay, it may bog under heavy load, but it will regain speed once I back off.

My Problem

If I restart the lawn mower within a minute of it being turned off , it will usually restart.

But if I leave it off for 5 minutes , it will not restart. And I have to try priming it and pulling the pull cord so many times for it to restart and sometimes I succeed and sometimes I do not succeed and need to go to a backup lawn mower to finish the lawn.

After an hour or so, it may or may not start. But if I try it the next day it will restart.

Does anyone, advise what I can do to fix it. I quite enjoy the 2 Stroke mower and feel something minor is amiss causing these issues.

I don't want to just throw money on stuff hoping to fix the issue, but if advice is this is the cause and more than likely fix the issue I am happy to proceed and advise all, with a follow up post.

Thanks in advance

Harry

Sorry Harry 2 strokes can be like that

Hi NormK,

So is there anything I can do

Hi Harry,
I'm not sure if the way I modify these carbys helps with this problem but I haven't had people tell me they are having this problem. 2 strokes have always had this sort of problem, it was really bad with the early Victas, not so much with the Powertorques

G'day Harry and Norm,

Usually with this type of problem I would do a service starting with checking the compression with a compression tester.

Sounds like the carby is sorted but it may have a plastic float needle that is sticking ,I would buy the metal needle with the float clip.

I've had starting problems when the 3 starter bolts come loose so every motor I work on I always check the bolts are tight and always
tighten the screws that hold the intake manifold to the engine as they can come loose with age.

Just to rule out any decompressor issues I would remove it and screw an old spark plug in , a short plug will do, the same plug the engine takes.

Using the plug to block the decompressor hole will allow you to now feel the compression when starting and when the motor gets hot
you should be able to tell from the starter if the compression is much less when hot than when cold.(This way you don't need a Comp tester)

If the above fixes the problem then put the decompressor back in and if the problem comes back you know the decompressor needs
replacing.

I'd also take the fuel hose off the carby and turn the fuel on to check the fuel flow rate from the fuel tap as I often need to clean
the fuel filter to get a better flow rate.

I usually find with the metal needles the motor requires less priming to start.

Cheers
Max.

Hi Max,


Thanks for the reply.

I do have a medal needle, so I will replace that first. Do I need the float clip.

The 3 Starter Bolts are not loose, or intake manifold bolts, I have checked them.

I will try the tip with a spark plug instead of the decompressor..

Also that without an decompressor , if I have less compression, I have cylinder issues.

Flow rate seems okay as , i did try this and it seemed to flow pretty easily.


As it is the festive season, I may not be able to get back with a reply for a while, but i will try when i get a chance to help others out also.


Great pictures.

Thanks

Harry

G'day Harry

If you already have the metal needle just use that and see how it goes.

Yes once you replace the decompressor with a plug if the compression is down you will know the rings / cylinder are worn.

If the top of the plug is in the way of the top plastic engine cover when you block the decompressor hole I would just
break the top porcelain part of the plug off.

Another test is to start the mower and turn the engine off by turning the fuel tap off and just before the engine stops if it
runs a lot quicker you have an air leak.

(If the engine accelerates or runs more quickly just before it stops, it could indicate that there is an air leak somewhere)

Cheers
Max.

Hello Max,

Thanks for the new tip.

As its Christmas, I am not sure when i can check it out and see what I find.


thanks

This has probably been covered here but I have a bad migraine and struggling to even read.
I recently had a very similar problem with a Victa Utility 2 stroke I was recently given though it would start hot it just wouldn't rev.
It turns out the plastic carburettor cover was turned away from the level mark meaning once it warmed up the float wasn't allowing enough fuel in to rev. I had no idea of the level mark on the white carburettor cover because my primary mower is a much older hand wind start (so much easier than pulling the cord (but I'm having trouble after replacing the spring on it the other day, (I'll get to it but not today) Victa Mayfair with the metal carby which is so simple.
Though friends own a local mower shop and were quick to point out the problem from a photograph I took and they really are a simple carburettor until you lose the needle in 4 inches of grass.
New needle, new white cover with new primer and new o'ring are sitting in my kitchen (don't ask, I won't lose it in there).
I was shocked though when the owner explained how to set the float height by adjusting the brass insert where the needle goes, he'd given me another cover with good primer bulb but it was a cheap after market unit he found in his stock (and gave it to me free saying it was used but in good condition) but somehow I cracked the fuel plastic nipple inlet slipping the fuel line back on. His son gave me another new unit better quality yesterday and set the float level with a file on the plastic needle, they've changed.

When did brass needles disappear?
Yes, I'm feeling old!

Hi Leo G,

Thanks for your reply.

The Carby Cover seems to be level.

Also an update for all.

I haven't had a chance to look at the Lawnmower.

i will get back to all when I do.

Thanks

Harry

Hi All,


I was able to do a bit of testing.

Day 1

I purchased the Metering Lever from [Censored] and installed the metal needle and the Metering Lever into the Carby.

I pumped the Primer bulb 5 times. It started on the 3rd pull.

I checked the RPM on Startup with the Throttle on Run. The RPM fluctuated between 3020 - 3040 - 3060.

After 30 minutes of cutting the Lawn. The RPM fluctuated between 3120 - 3140 - 3160.


I Turned Off the Fuel Tap and the Lawnmower ran normally until 1-2 sec before it cut out where it revved a little bit higher, maybe 100 rpm higher.
So, I don't think there is an Air leak. But you guys might need to advise.


I Turned the Fuel Tap back On, Pumped the Primer Bulb 5 times, where it took about 10 pulls to start. The RPM fluctuated between 3120 - 3140 - 3160.


After a few minutes of running normally. I turned the Lawnmower Off normally by putting the Throttle to Off. I then tried to restart the Lawnmower.
The Throttle was set to Run, and it started after 2 pulls. The RPM indicated was 3120 with no fluctuations.


So, when I get a chance again, I need to retry and also leave the Lawnmower off for a bit longer maybe 10-15 minutes to see what happens.


I don't think I fixed it yet, I have probably eliminated a possible sticky needle. I still need to set the throttle just past the Cold start spot to start when cold.
This never used to be the case originally and it would always start on first pull. So even though I have replaced the Diaphragm and Orings on the Carby (Carby Kit).
Maybe the Control Spring and Return Spring are not working Properly.

My next test will be to remove the Decompression Valve, block the hole and try to start the Lawnmower Cold and then when hot after 30 minutes to check compression
and see if the Decompression Valve is faulty.

I will get back to all after my next test.


Thanks
Harry

Harry,
you can easily check the decomp valve, remove it and put a bit of hose on it and suck on it, if it closes it is fine

Hi NormK,

I will try that. but I also want to see how Compression is cold and compare it to hot. As per maxwestern's recommendation.

If compression concerns you just give it a hone and put a new set of rings in it

Hi All Again,

Day 2

Cold Engine.

I removed Decompression Valve.

I pumped the Primer bulb 5 times. It started after about 10 pulls of the Cord with the Decompression Valve removed. (Not what I expected)

Whist the lawnmower was running I still had the Decompression Valve connected to the black hose, it would cause the valve to close.


I run the lawnmower for about 30 minutes when it run out of fuel. (I forgot to fill Fuel Tank).

When I filled Fuel Tank, I noticed that fuel was leaking from the Primer Bulb hole.

I presume this means that even with the new metering lever in place it didn't stop the fuel from over filling and coming out of the bulb.

I had to tap on the white Primer Cap to get it to stop flowing through the Primer Bulb hole.


Whilst the Lawnmower was hot , I checked Compression, it felt about the same amount of compression as it is cold.


So now, i am curious as to why it leaked fuel through the Primer Bulb, I will reinstall the Original Victa Primer Cap as maybe the aftermarket Primer Cap bought through Amazon is no good. I may keep using the aftermarket Diaphragm.


Any ideas, as to why without the Decompression Valve it took 10 pulls to start from cold and why it overflowed.



Thanks
Harry

Harry are you saying you removed the decomp and obviously put a spark plug in the hole. If you can start it like that it needs new rings, it should give a big kickback

You are probably on the right path, as I didn't think it would give me a kickback.

More info.

Day 2 later on,

As I was getting nowhere. I decided to pull apart the Carby and see what was happening.

Upon re-installation I found it was jamming on the Kill switch Pin. This originally occurred quite a while ago before I got it working but didn't think it was an issue now.

After trying to adjust the throttle cable and throttle cable screw (near Filter housing), I decided to leave it out. But leave the Kill switch hole open.

After Priming 5 times and pulling the pull cord 3-5 times it would start but now rev up to 4200 rpm.

So , I get the feeling it has some thing to do with the Carby and Throttle Cable setup and compression.

But I am about to give up, i think it is beyond me. I don't know what to do next.

And as I have an older green base 2 Stroke Lawnmower, I am better off pulling the old green base Motor and installing it on the newer Victa base/Covers with its 4 Blade setup. This motor always starts first try and doesn't give me any issues when hot.


Thanks
Harry

Hi Harry and Norm,

The Powertorque motor will not kickback with the spark plug in the decomp hole ,Victa made Powertorque motors that never used a
decomp the hole was never drilled or threaded in the head on some Victa mowers .

Kickback is usually felt when you try and start the motor without the blade plate fitted as the blade plate acts as a flywheel also
the spinning mass is reduced on a Victa 24 with a V belt to the cutter plate.

I even made a video showing no kickback on a Powertorque without the blade plate fitted but the boss on the crank was slightly
heavier than standard because the mower was a 460 utility

.

The compression hot sounds ok if you can still feel a fair amount of compression so you can put the decomp back in.

Just sounds like a carby issue, if the kill switch is playing up buy a new rubber for the wire.

If fuel comes out the primer bulb it means the needle and seat in the carby are not shutting off and the fuel level
in the carby gets too high and fuel leakes out the primer ,fix the needle and seat so it shuts off and has a good seal
when the fuel is at the right level and this will stop fuel leaking out the primer bubble.

Video below at the end shows how to test the needle and seat to see if it's sealing when closed, without a pressure tester
you will need a hose connected and blow air down the fuel inlet to see if it's shutting off.



Cheers
Max.

Sometime the needles would get stuck closed and this can make starting more difficult and more priming is required.

The video below shows how to overcome a sticking needle.

Also when I start a Powertorque I just put the throttle on full then when it starts back off the throttle.

So Max,
why do I have massive kickback problems with my PT's on 24 bases. They need at least 1kg added to the crank to prevent them kicking back and near breaking my fingers

G'day Norm,

I thought we talked about this on a lot of occasions , that was why I made the PT video to show you don't need a lot of weight
on a PT to stop it kicking back under normal circumstances.

As we know



Flywheel Mass and Engine Dynamics:
The flywheel on an engine serves several important purposes: it helps smooth out the delivery of power from the engine, maintains momentum during the power stroke, and provides mass to aid in starting. The larger the flywheel mass, the more inertia it has, and the smoother the operation of the engine can be.

Direct Crankshaft Connection:
In a mower where the blade plate is directly attached to the crankshaft, the flywheel mass is effectively utilized throughout the starting process. The engine and blades are directly linked, meaning that when the engine gains momentum and starts firing, this momentum directly translates into rotational speed for the blades. The inertia of both the engine and the blade plate works together, making starting smoother and minimizing potential kickback.

V-Belt Drive System:
In a V-belt drive system, the engine's rotation is transmitted through the belt to the blade plate. This means that the mass of the blade plate does not contribute effectively to the flywheel effect because the load (the blade plate) is not rigidly connected to the engine.
When starting, the engine is attempting to overcome the resistance of the blade plate, but the V-belt tends to absorb some of the energy required to start the blades turning. As a result, the effective flywheel mass is reduced because some of the energy that would be contributing to inertia (as seen in a direct connection) is dissipated through the belt system.

Added Flexibility and Loss:
The flexibility of the belt system means that not all the rotational force generated by the engine is transmitted immediately to the blade plate. Slippage or tension variations in the belt can further reduce the effective mass that contributes to inertia during startup.
Additionally, if the blade plate has a significant mass itself, it requires more energy to start moving. The V-belt drive can cause a lag or delay in how effectively this mass contributes to the overall inertia during startup.

A V-belt drive system separates the engine's power delivery from the blade plate, which diminishes the effective flywheel mass during starting. The inertia and benefits of flywheel mass aren’t fully realized because the engine's energy isn’t transferred directly to the blades, leading to a potential for increased kickback and reduced starting efficiency compared to a direct crankshaft attachment.

I suggested adding mass to the crank on the PT crank with a v belt drive to overcome the kick back problem but that's not
the only way to overcome the kickback problem.I've suggested other ways before but because you had the weight working
you weren't interested in trying something else ,which is fair enough.



Retard Ignition Timing:
Retarding the ignition timing can help reduce the likelihood of kickback. If the ignition fires later in the compression stroke, it allows the piston to move down before the combustion pressure can push it back up, minimizing the abrupt force on the starter mechanism. However, this may also affect engine performance, so finding the optimal timing is essential.

Adjust Decompression Mechanism:
Decompression Timing: Modifying the decompressor to activate later can be effective. A decompressor helps relieve cylinder pressure during starting, making it easier to turn the engine over. If you delay its activation until the engine is at a point where it has started turning over, the compressive force can be reduced, effectively lowering the likelihood of kickback.
Automatic vs. Manual Decompressor: Consider utilizing an automatic decompression system that engages during starting but only releases after startup. This allows maximum assistance during start without affecting operation once the engine starts running.

Starter Engagement Mechanism:
A more sophisticated starter engagement mechanism can help manage the initial load on the starter. A system that smoothly ramps up the tension in the belt or utilizes a soft start can reduce the kickback effect.

Using an Anti-Kickback Starter:
There are starters designed specifically to minimize kickback. These starters can incorporate features like a ratcheting mechanism that allows the starter to disconnect under certain load conditions, preventing the rotational forces from being transmitted back to the starter cord.

Improved Belt Design and Tensioning:
Review the design of the V-belt drive. Using a belt with different material properties or improving tension management can help ensure a tighter grip and reduce slippage. Proper belt tension can minimize energy losses and allow for better power transfer, also aiding in smoother starts.

Flywheel Design:
If you cannot add weight, consider designing a flywheel with a different configuration. A flywheel with more mass towards the edge (increased rotational inertia) can store more energy and provide smoother power transmission, to help eliminate kickback.


Cheers
Max.

Yes Max,
Adding weight to the crank is the way to go, but it is very time consuming for me on my little lathe. I did have a full crank Tilta -Cut that suffered violent kickback and I ended up adding weight to the crank and that solved the problem. Once they have this additional weight they start easier and have more power because of the extra spinning mass

Hi All,

Day 3

With Kill Swicth bypassed, Primed 5 times and now in the cold position it fired on the 3rd pull. Did some lawns for half hour and now similar to before will not start even though I let it cool down for an hour.

So I don't know what to do next. I started my green base 2 Stroke it started first go runs at 4100rpm. I can leave it rest for an hour and it will start in the run position first pull. It might rev a bit high , but I might need to do the brass washer trick to slow it down a bit.

I might do a heart transplant and use this motor on the newer base.

Nothing new about any of this Hazzaman, I think with worn rings the bore expands slightly and the worn rings just can't create enough compression.

Hi Max,
I had a GCV160 Honda that was giving me big kickback problems on a 24 just as bad as the PT's do. I'm not sure if they lightened the crank on the GCV's but all I can think of. I fought it for a few days trying to add weight to it but couldn't hold them tightly enough in position so ended up pulling the motor off, put it on a standard Victa base and out the door. The bloke sent me a text a few days later saying he was happy with the mower and how well it ran. What I don't understand is why I don't have kickback problems with the Deutschers apart from the bigger ones with the cam issues

Hi Harry,
It could be compression too low when hot but you really need a compression tester to check that .

Ignition Coil: If the ignition coil is getting weak when hot, it might cause intermittent starting issues. You can test for spark when the engine is hot.

Compression and Engine Condition

Compression Check: Use a compression gauge to ensure the engine has adequate compression. .

Air Leaks: Check for air leaks, particularly around the intake manifold or carburetor gasket. An air leak can lean out the mixture and make it harder to start.

Possible Considerations

Overheating Issues: If the mower is overheating, it can lead to "heat soak" issues, where it gets hard to start after being turned off briefly. Check for blockages in the cooling fins and ensure the engine is not excessively dirty.

Cleaning and Maintenance: Regularly clean the air filter and ensure it's not blocked, as a dirty air filter can affect performance.

I'd check fuel flow when it won't start as sometimes the fuel cap breather doesn't work ,also when you turn the mower off turn the
fuel tap off that will rule out over fueling.

Hi Norm,

I'm sure you would have Deutscher kickback problems if you used a Powertorque or the Honda motor.

When you look at my video of starting the Powertorque without a blade plate the engine spins fast from the starter cord
but I remember starting Victa 24's with the side pull starters and they were so much slower to spin over as you just end up getting
drag from the v belt drive turning the blade plate,this just adds to a kickback problem.

You can't compare one motor that doesn't kickback to another that does unless you know all the specs and condition of the motors as there
are a few things that contribute to kickback.List below of specs that can be changed so the engine can suit other applications.


Compression Ratio: Higher compression ratios can lead to stronger kickback. A higher compression means that the engine requires more force to turn over, which can cause the starter mechanism to experience sudden reversal when the ignition occurs.

Ignition Timing: Incorrect ignition timing can significantly contribute to kickback. If the spark plug fires too early while the piston is still rising (before top dead center), it can lead to a violent reaction that causes the engine to kick back.

Flywheel Weight: A heavier flywheel tends to smooth out the rotation of the engine, helping to prevent sudden changes in momentum that can lead to kickback. Conversely, a lighter flywheel may exacerbate kickback.

Crankshaft Design & Weight: The design and weight of the crankshaft can influence the inertia during startup. A heavier crankshaft may absorb some of the shock associated with kickback, whereas a lighter one may not.

Starter Type: The type of starter (manual pull starter, electric starter) can also affect the experience of kickback. Manual starters can provide less mechanical advantage than electric starters, potentially leading to more noticeable kickback.


Fuel Mixture: The air-fuel mixture can affect engine performance. A rich mixture may lead to lower temperatures and incorrect combustion timing, which can contribute to kickback.

Engine Condition: Worn components, such as valves, piston rings, and bearings, can lead to inefficient combustion and increased likelihood of kickback.

Cold Engine Effects: Starting a cold engine can change its dynamics. Increased friction and oil viscosity can contribute to the behavior of the engine when it first starts, potentially increasing the chance of kickback.


Factors Affecting Kickback Due to Cam Design

Camshaft Profile: The shape and design of the cam lobes influence the timing and duration of valve opening and closing. A more aggressive cam profile can result in quicker valve motion, potentially increasing the likelihood of kickback if the engine is not designed to manage such forces effectively.

Timing of Valve Events: If the camshaft timing (when the intake and exhaust valves open and close relative to the position of the piston) is not optimized, it could lead to back pressure during the compression stroke. This can create resistance when attempting to start the engine, leading to kickback.

Compression Ratio: The cam design can influence the effective compression ratio of the engine. Higher compression ratios can lead to increased resistance when starting, resulting in more potential for kickback. Camshafts designed for performance often increase compression at specific points in the engine’s cycle.

The design of the decompressor in a small engine can play a significant role in reducing or eliminating kickback during starting.

Yes the Honda 4 stroke crank doesn't look to have much weight out from the main shaft ,the early Victa full crank has a lot more
outer weight on the crank ,If adding weight to a powertorque is time consuming why not just fit the full crank 2 stroke motors
to the Victa 24 mowers.


There are a lot of different specifications a factory can change on a motor to stop it kicking back when starting when used in
other applications .

I see a lot of people that have an original working mower from the factory then when the engine is worn out they just take an engine
that is not to the factory specification to suit their mower and fit the wrong motor then it kicks back when starting.

Then you end up with people selling cheap mowers that don't run.

Cheers
Max.

Hi Max,
fitting a full crank motor to the later 24 bodies is not straightforward, I have drawn up a sliding plate that should allow me to fit F/C motors on the later bodies but I would need to get them laser cut and it all ads to the costs and at this stage I am not 100% sure it will work

G'day Norm,

Looking at the pic below it just looks like you get a flat 1/4 inch plate and drill the holes to fit the PT holes in the base then
drill 4 holes for the full crank motor and drill a centre hole then make the adjuster for belt tension.



Cheers
Max.

Yes Max,
I was thinking of going the other way putting PT motors on the F/C bases. The PT motor is great on the 24's once you get past the weight problem on the crank and I have a lot more PT motors here than full cranks. I have a lot of 6mm plate here but the only way I can cut it is with a grinder as I don't have a plasma cutter. Think I will have to get one

There was a Victa collector not long ago selling off his full crank 2 stroke mowers for $5. each Norm except they
were interstate.

May as well use up some PT motors if you already have good ones.

The 6 mm plate isn't too difficult to cut with the 9 Inch Angle Grinder ,it's just the cutting discs don't last that long.

It is cutting the round hole in the plate for the motor to to sit through is the problem. Hole saws will do it but it is hard work

A 30mm hole cut with a decent hole saw like Sutton through 6mm plate tales about a minute and a half if you drill a clearance hole first
Norm.

Mark the hole with the hole saw then drill a 10 mm hole or bigger on the edge of the circle this will remove the swarf ,I also use an
oil can for cooling and Lubrication.

You can use this method to drill through 2 inch thick steel .I usually use an old Sher 2 speed drill set on slow speed with a 1/2 inch chuck.

Cheers
Max.

Yes Max,
The hole to fit the bottom half of the crank through is about 80/90mm in diameter. I do all that sort of drilling in my drill press but plasma for that stuff is so much easier. Problem is all this stuff adds up and as you know there is no money in fixing mowers. I need a plasma, a bottle of migshield gas and a bottle of oxy and a bottle of acetylene all ads up and it is hard to justify when I am nearly 80 years old

Hi All


As I have an older 2 Stroke Green Base Rapier 2 Blade Lawn Mower. What I might do is use the 4 Blade System from the newer Lawn Mower on my older 2 Stroke Green Base Rapier 2 Blade System Lawn Mower.

This way I can keep cutting the lawn without worrying about not being able to start it after turning off for 10 minutes.

Thus, this will allow me, plenty of time to pull it all apart, clean everything and source a new Throttle Cable and G4 Carby as I am now thinking the issues stem from there. If i pull everything apart, I can do the Large O-ring replacement and also see if I can borrow a proper Compression Tester to check compression.


I will persevere, it might take me months, but I will try to remember and post what happens

Hi All,

A small update.

I purchased a cheap Compression Tester from Ebay. So I can test it's compression.

With the Decompressor in place , I get 25psi.

Without the Decompressor and the hole plugged, I get 35 psi.

Is these figures correct for a Powertorque Victa 2 stroke lawnmower.

Also I pulled off the Carby and noticed I have quite bit of dirt inside the Carby air intake. It looks looks very dirty from dirt being sucked in. It seems the clamp that goes around the hose and Carby does not Seal enough or it is getting sucked in from the top of the hose.

I am hoping for advice from someone that knows what should the psi of these lawn mowers should be. If it is too low I can pull it all apart and replace the O-rings and Piston Rings.

Thanks
Harry

Hi Harry,

The lowest compression that I would use is 50 psi with the comp tester on the end of a flexible hose without the hose compression
probably is around 65 psi.

It's usually cheaper to buy a good mower at a tip shop for $10 to $20.or gumtree ,garage sale etc

Cheers
Max.

Hi Max,


Thanks for the advice.

Good point about a Tip Shop or Gumtree.

Let's see what happens.


The moral of the story is I should of bought the cheap Compression Tester at the start it would of explained a lot.

Hi Max,


Can you please have a look at the below pictures and advise if I purchase the below kit from Ebay will it work or am I wasting my money.





Thanks

Harry

G'day Harry,

That bore looks worn enough to at least need honing ,but it depends after the bore is honed and the piston is measured as well as measuring the bore wear then the maximum clearance should be no more than 11 thousandths of an inch to be suitable for new rings.

A new piston should not be used in an old bore.

OutdoorKing have a rebored engine for $80.https://www.outdoorking.com.au/clearance-items/victa-power-torque-rebore-err1352n

PowerTorque manual https://www.outdoorking-forum.com.a...del/Power%20Torque%20Engine%20Manual.pdf


As your 2 stroke mower engine was so low in compression I wouldn't spend time fixing it as a replacement mower is
cheap on FaceBook Marketplace ,Gumtree ,eBay

I've seen piston ring sets for around $15. online but depends how worn the engine is.

That 11 thou clearance sounds a lot from the manual as usually motors are about 2.5 to 5 thou maximum piston to
bore clearance

Cheers
Max.

A full crank 160 cc Victa 2 stroke maximum clearance between piston and bore for new ring replacement is 8 thou.

There's always people giving away mowers.




Cheers
Max.

Hi Max,

Thanks for the Manual. much appreciate it.



An Update,

The Old man got a 2 Stroke Lawn mower from his friend.

It is a Victa Pace Model PAS201G.

It has no Decompressor installed. There is no hole for a Decompressor at all.

The Lawnmower seems to have been taken to a repair shop that said it is not repairable. (Compression???)

The first thing I noticed was it has the white carby cover on 90 degrees from horizontal. Easy fix anyway.

It had its pull cord mechanism pulled off, so I could see the Piston rod. The whole area was pretty clean, so it doesn't seem to have sucked in any dirt.

I decided to put it together and see what its compression was.

Since it has no decompressor there was no need to plug the hole with a Spark Plug.

After pulling the Cord 5 times, the Gauge reaches 60 PSI.

It isn't 80-100 PSI but better than 35 PSI I get from the old motor.

My question is do I proceed overhauling the Carby and installing the Float Lever and testing.

I know Maxwestern mentioned no lower than 50 PSI.

Or do I wait to find another lawn mower with a better compression.


Thanks
Harry

If you wait then nothing will happen...if you go ahead the better mower will turn up! It's a win win situation.

Danny

Hi Harry and Dandare,

Most Compression testers aren't accurate ,50 psi is the lowest I'd use with my comp tester as I know the real reading will be at least 65 psi
and have used mowers like this for 10 years and haven't had a problem.

here is a video showing how far out different comp testers can be.




I'd go and fix the carby and use the engine with the higher comp.

You can run a mower on 65 psi ,below is a LawnBoy motor spec that has minimum 65 psi cold.

If the Schrader valve isn't at the spark plug end on the compression tester the flexible hose just adds to the compression
chamber volume ,thus giving a lower reading.

Cheers
Max.

Hi Dandare and maxwestern,


Sorry for the late reply, I was at the Parents.


Good advice Dandare, I just thought more knowledgeable people might advise otherwise.



Thanks Max for the attachment and additional info. That's the exact Compression Kit i got (Red One). I will view video after this post.


I plan to pull off the Carby tomorrow check it out and if required use the newer parts from the other carby on this carby with the float Lever.

And give it a try, if all goes well I will transplant the Motor onto the newer base.


Thanks for the reply max.

Harry,
If you are going to start this motor make sure it has a blade carrier on it because without it it will give you a severe kickback, hurting your fingers

Hi NormK,

Thanks for the advice. The aim is to fix it on the current base and then when I am sure it is working remove the motor and install it on the other base.

Just a reply about the Video on the different comp testers ,I can't believe how much of a difference he got with the 2
readings,I suspect the o ring was leaking on the cheaper red box tester as he said he only tightens them finger tight
so it could have come loose or compression leaked past the o ring as I've had the o rings leak compression before
on testers unless I tighten the plug hole fitting with a socket so it's tight.

When I tighten the tester tight in the threaded hole the O ring eventually fails and needs to be replaced but now
I have just installed a spark plug washer on my comp tester threaded connector.and that should last for ever.

The longer the flexible hose the more your reading will be down from the correct reading if the
Schrader valve isn't at the spark plug end on the compression tester with small engines.

I checked a Victa 2 stroke 160 cc motor ,the short comp tester has the Schrader valve at the end that goes into
the head of the motor and the longer tester has the Schrader valve up the other end near the gauge.

I get a reading that is 20 psi different with the two comp testers (longer tester is 60 psi ,short tester is 80 psi)

I usually like a small motor to be on at least 50 psi with the longer tester so that may be 70psi for a cold reading and
is the lowest I will use a mower ,I find the mowers can still last 10 years but can stall a little easier in long grass,they will
start straight away after stalling hot but find any lower comp reading and they can be a pain to start hot after stalling
in longer grass , most people prefer at least 85 psi as a lowest compression reading.

The short tester may be a little low reading also because you are still making the combustion chamber bigger
with this tester than if you had a spark plug installed.

Cheers
Max.

Hi max,

My Chinese made Compression Tester does have a Schrader Valve at the bottom of the hose, but as usual it does seem to leak when you are blow in the hose. So you get what you pay for.

Sunday Update,

After getting 60 PSI cold , I cleaned the motor and installed the Float Lever, pulled apart the carby and checked it all and put it all together. After endeavoring to get the throttle cable to work properly. It seems to work now. You can go half way, it finds a bump and when you push a little bit more it clanks and goes to full throttle.

So

After priming a few times and pulling the cord a few times it started. It smoked around the exhaust and settled after a while. I run it for a little bit and turned it off.

After having it off for a few minutes, I decided to start it again. Unfortunately this time it did not start. I pulled out the Spark Plug and tried to check Compression. Well would you believe it compression when hot is 45 PSI. 5-10 minutes later it reads 55 PSI. 5 -10 minutes after that it got back to 60 PSI.

Unfortunately this motor seems to also have a Compression issue too.

I did adjust the Poppet Valve back to A, I found it about halfway between A and C. Would this affect the restart when hot. ( Poppet has 4 A C)

Any advice


I'll need to keep looking for a Hard Rubbish 2 Stroke Motor.

Hi Harry,

Yes I've had the same problem when the motors are below 70 psi cold with an accurate comp tester (sounds like your tester
is accurate with the Schrader Valve at the bottom of the hose,) They are hard to start hot when the compression is down..

If the tester is slowly loosing pressure after a test you may be able to replace the Schrader Valve to fix it.(it should screw in)

The carby poppet should be set to C but this setting won't effect starting it's more a long term setting so it's not too rich or
too lean.

The two choices would be, one look for another (engine / mower ) or two just put some new piston rings into this motor
that is on 60 psi cold.


If you replace the rings you will need to make a tool to get the conrod / piston out. (just cut an old socket up)

https://www.outdoorking-forum.com.au/forum/ubbthreads.php/topics/33821/1/victa-special-tools.html

Cheers
Max.

Hi Max,

Thanks for all the info.

Just a set of standard Piston Rings, not oversized.


Harry

Yes Harry if the bore is standard size ,they usually are, just use standard sized rings.

Cheers
Max.

Thanks Max,


It will be a while until , I re-post again.

Thanks for the advice.

Better if you can give the bore a hone to get it freshened up

Yes Norm it would be better, but I didn't mention one because if you are only repairing one engine and a hone is about $20.
plus new rings and a head gasket ,it could be a better option to buy a used mower .

Harry mentioned the motor looked clean with the starter off and if the bore looks good, I've fitted rings without a hone
and they bed in after a while.

I think you can get away without a hone if the wear is minimal; often, simply replacing the rings with proper break-in procedures is sufficient for most situations.

I never Hone a Briggs with alloy bore.

If the bore looks ok sometimes I don't like to hone the bore as the piston is already close to it's maximum bore clearance
so I don't want to give it any more clearance from a hone.

When I do use a hone I put 1200 wet and dry around the stones so the very minimum is removed.

Cheers
Max.


Cheers
Max.

Always pays to check the ring gaps in the bore before putting them on the piston as well, not that it is a problem usually but always pays to check

Hi All,

A question from Sunday's Update.

When I was cleaning everything and installing it back together I noticed the vacuum control button fitted on the motor housing, that has a hose connected to it and the Carby Cap has no hole on it. The other faulty motor definitely has a hole on it and thought it was strange.

Is this the reason why it seems to clank to Full throttle as there is no air pressure at the top of the Diaphragm. I tried starting it on cold position and it wouldn't start, i pushed the throttle forward just before it clanks to full throttle and tried again, It tried to start and once I push it over the clank to full throttle it started.


Throttle Cable is smooth, no kinks in it. I have tried it without the Red Spring and Carby Cap and it does not jam at all. It seems only when the Spring & Cap are on.


Thanks
Harry

Hi Harry,

The carby diaphragm cap should have a vacuum line connector on it .

With the throttle cable sticking or jamming ,I usually just bend the cable to stop that ,see pic below in the red circle,
that is what the end of the cable that goes into the carby looks like after it's bent to stop it sticking.


Cheers
Max..

And that is why I cut the3 lumps off the lifter, no cable jambing for me, nice and smooth

Hi Max,

Yes the Diaphragm cap has a vacuum line connector on it, it is at the end of the tube where it connects to the Motors frame that has no hole in it.


Thanks for the tip about the bend, I might give it a go and see how it goes.

Hopefully during the weekend.


Thanks

Hi All,

Saturday Update 8/3/25.


I have moved the Poppet Valve to C.

I have not bent the throttle cable as mentioned by Max.

I still have the original vacuum control button without a hole that is fitted on the motor housing and is connected to the Diaphragm Carby Cap vacuum line connector still on.

I tried starting it on cold position and it wouldn't start, i pushed the throttle forward just before it clanks to full throttle and tried again, It tried to start and once I push it over the clank to full throttle and pulled the cord it started.

So it seems to like to start in the run position only.

Does having a Vacuum Control Button without a hole effect the way it starts.


Secondly

Also I ran the lawn mower for 1/2 hour and tested its RPM and Compression. RPM was 3660 RPM and Compression was about 60 PSI.

I tried to restart the Lawn Mower on Run and it started after the Second Pull.

This time I ran it for another 20 minutes and its RPM was about 3820 RPM and Compression was about 55 PSI.

Again I started the Lawn Mower on Run and it started after the Second Pull.

This time I ran it for another 30 Minutes and its RPM was about 3660 RPM and compression was about 53 PSI.


At the moment my lawns are very dry and its a dust bowl. (The lawn mower is covered with dust).

So having a Vacuum Control Button without a hole affect the way it starts, and does the above RPM and Compression readings , still warrant a Piston Ring Replacement. I am happy to do it , if it will help compression & starting. Also to replace the Vacuum Control Button with one with a hole.


Thanks

Harry

So what is the problem Harry, if you can start it with 2 pulls when it is hot just keep doing what it wants to do. It is a 2 stroke, don't overthink it

Hi NormK,

Thanks for the reply.

what about it not starting when cold , in the cold position, it seems to only start after a few pulls and being placed in the run position, would this be detrimental or not.

Start it where it wants to start Harry , it is a 2 stroke they can be temperamental to start but the only way you can damage one is if you straight fuel them

Thanks NormK,


I will see what it does for the next few months.

And I might do what maxwestern recommended and bend the throttle cable and piston rings, but for now , I just leave it as is and monitor Compression after using it few a few hours when doing the lawns.


Thanks to all.

If you feel like it put a set of rings in the other motor and then you have spare engine sitting on the shelf ready to go if you ever need it

Hi NormK,

Was thinking about it also.

I might order a set, use the current motor a few more times making sure its Compression doesn't move from 50-55-60PSI , as it did drop the first time to 45 PSI the first time I put it together on the newer base.

Thanks

G'day Harry

If the vacuum is not connected to the carby diaphragm the governor won't work ,I wouldn't worry about it
on an old 160 2 stroke as they usually have enough power anyway.

I can't find a Victa factory lowest compression in psi recommendation to replace the rings ,but this
is the one a shop has already said is too low and I recommended about 70 psi cold as the lowest I'd use,
Honda 4 strokes recommend 85 psi cold as the lowest .

Low comp can mean hard starting and easily stalled under load.

Victa give a maximum used piston ring gap at 16 thou and with new rings the mimimum ring gap is 8 thou.

A Victa 160 full crank motor has it's maximum torque figure at 2000 rpm ,I haven't looked at Power torque
figures but it just shows you don't need to scream the motor out normally to cut grass unless compression is down.

I always start the Power torque mower on full throttle and back it off when it starts.

Having a Vacuum Control Button without a hole won't affect the way it starts.

I'd put rings in this one just because it's down a fair bit ,other 2 stroke are recommended for a rebore
with 8 thou bore wear from standard.

A full crank 160 victa is 8 thou clearance maximum between the piston skirt and bore before
needing a rebore so I'd use that figure for the Power torque motor.

To check the ring gaps you push the rings evenly down the bore from the top by about an inch.

You can spend $30. on this one or get another mower or just use it until it won't go any more,
up to you.

Cheers
Max.

Hi Max,

Thanks again for all the info. Very useful.

Good to know about starting on full throttle, and that the Vacuum Control Button doesn't need to have a hole.

I will buy a Standard Ring Kit and use it on the 60 PSI Motor.

I understand the original is down to 45PSI and really needs a rebore. So I might Google how to do a rebore on a 2 Stroke Victa and maybe give it a try.


I will post when I have ordered and installed the Standard Piston Ring Kit and advise what PSI I get on the 60 PSI motor.

Thanks

Harry

Hi All,

Sorry for taking so long to get back.

With work commitments, going overseas for a while. I have just now had a chance to get back to the Lawn mower and replace the Original Piston Rings with a new Standard Ring Kit and use it on the 60 PSI motor.

I found that the Piston had a few grooves where gravity pushes it down.

Unfortunately I didn't buy a new Piston , just the Piston Ring Kit.

I followed YouTube Videos and replaced the Piston Rings.

And reinstalled the Piston and Conrod, I reused the Gasket as it seem in good condition.


All I can say is that I did not get an increase in Compression.

Compression has remained the same. It starts okay after priming and a few pulls.


It starts pretty much straight away if I turn it off for a minute and then restart it.


I reused it's original Carby with the other Faulty(45PSI) Motor's Throttle lever/Cable/Hose , Fuel Tank and Covers.

After replacing the above stuff and priming again, it started after a few pulls also.


For now , I will let it go and see if I can get it started in a few days. I might need to prime it a few times and start it on full throttle for it to start , but I am happy with that as i have been advised it is not a issue.

If I remember I will post if I need advice.


With the Faulty 45PSi motor , I am keeping for parts only.

Also the funny thing is, if you pay attention there are people throwing out Hard Rubbish that's worth taking. I have been able to score 2 other Late Model 2 Strokes a Victa VSZ160 Razor and a Victa Bronco.

So I am pretty much all good for 2 Strokes. All the Victa Bronco needed was a clean, and the Pull Cord Return Spring Re-bent into position a new Pull cord and Handle installed. It started after priming and on the second pull.

I have not tried the VSZ160 Razor.


Thanks to everyone for their help.

Harry

That is good Harry, people hate them because they can be problematic and 90% of the problems relate to the float needle. Once you get that sorted they can be fairly reliable

Hi NormK,

Correct, that's why I much prefer to fix an older Lawn Mower than buy a new one.

I did for the first time see an electric lawn mower in hard rubbish. All I can say I didn't stop.

I feel people think that Electric Lawn Mowers are better than Petrol, but like everything these days they aren't built to last and who knows if they last as long as a Victa 2 Stroke or an older B&S Quantum 4 Stroke Lawn Mower.

Harry, no way will an electric mower last anywhere near as long as an old Victa.. And if the rings wear no big deal chuck another set in

My VSX160 had a similar issue - turned out to be a dodgy coil. Took it to a (sadly now closed) Mower Shop in Sydney who talked about having to pull apart a spare PowerTorque he had laying around to fix mine. Given we can get carburettors, and blades etc still fit, I'm concerned that when the coil goes next time, I'll have to scrap the mower...

Never fear AMP, unusual for a PT coil to fail but I would have over a hundred sitting here