OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Victa Two Stroke Engines VSX160 heat related power drop yoyo

Hi,

I've had a read of many of the threads and currently have my mower in pieces.

It's a VSX160 on a mustang alloy frame with a mulching blade base purchased new in 2003. The mower has worked well until recently and in the previous 8 years has been run on a diet of premium unleaded (98 ron) on a 25:1 mix with a few spark plugs in that time and an air filter. It's used for a 100m2's of lawn every 2-4 weeks.

Recently it started after running for a few minutes to start to drop the revs, it would increase almost straight away and would continue to do this every 5-10 seconds until it became progressively worse and would stop running after around 5 minutes (I suspect this is more to do with the load it's under when mowing and if left to run it would just decrease and increase speed for quite a while), when it's restarted it will run ok for 30-60 seconds and start again.

There is no oil leaking from the top oil seal, everything looks ok in that area but there was some oil sitting in the bottom near the piston and there was oil over the exhaust. There is no oil underneath the mower and all that area looks dry.

The pistons does appear to have a few minor score lines on them but runs fine with no noise apart from when the revs start dropping.

I have not pulled the carburettor apart yet as I'm not sure if this could cause the problem I mentioned.

Looking at the contacts on the side of the flywheel these seem ok but do have a little surface rust on them. The larger set of two contacts side by side with a gap in between are around 2mm gap whereas the other contacts which are smaller on the other side of the flywheel are closer.

The wire all "looks" fine with no sign of wear and the plug looks ok (about 18 months old).

Is it likely that the problem is the electronic coil that is playing up or should I look further, clean up the contacts on the flywheel and the coil along with the connections, replace the spark plug and put it back together and hope that it's resolved? If it's likely that it's the electronic coil I would rather replace it now, worst case is that it's not the electronic coil and I could sell the old one on ebay for probably half what the new one cost.

Any suggestions? Thanks in advance, I've learnt a lot from the posts on here. I can post photos of any relevant areas.

Hi Maverick, and welcome to Outdoorking.

The symptom you have described - cyclic variation in the speed of a governed engine - sounds like a common problem usually called "hunting". In the great majority of cases, the cause of hunting is lean mixture. Your Victa may have accumulated some crud in its fuel tank and it may be obstructing the filter they usually have in the tank, at the fuel outlet fitting. You will need to clean that filter if it has not been cleaned recently, and verify that fuel flows full-stream from the fuel pipe at the carburetor end, when it is disconnected. If it is not the filter we will have to talk about the carburetor, and whether it has crud accumulated in its float bowl's needle and seat (i.e. some of the sediment has found its way past the filter), but I suggest you begin with the filter and only attack the carburetor if that is not the problem.

In an unrelated matter, the clearance between the two laminated steel poles of your ignition coil, and the flywheel, should be 0.010-0.012", which is the thickness of an ordinary visiting card. The amount of clearance, and it being equal on the two sides, is fairly important.

Thanks Grumpy


Thank you, I will check this tonight and clean if required and check the flow. I thought heat related because it took a while to start occurring but of course before you start the engine you prime it.


Ok there may be a problem here in that case, I noticed that the gap is tight with the two large pieces separated in the middle but the gap with the smaller one piece is probably 3 times the distance. I will check the measurements tonight. I hope the distance can be adjusted without removing the flywheel???

With the flywheel, if the clearances are different side to side i do not see how you will be able to fix that. It is not adjustable. The only thing you can do is adjust the coil closer too or away from the flywheel.
I would suggest you leave it be.
To tell you the truth, i have never checked both clearances, use a business card on the square ones and im done. Once the clearance is set the only way it can alter is if it is hit or the bearing gets sloppy.

The fault is most likely to be carb or fuel related. I would suggest you put the mower back together so you can test this side of it.

As grumpy said, fuel flow.
It sounds as if it is running lean.
Another trick you can also try is pushing the primer button while it is running, see if that makes it pickup in revs.
Leave the mower sit with the fuel tap on. Start it and turn the fuel off. Time how long it takes for the motor to die out.
Then fuel on, leave it sit again, start the mower and leave the tap on then time how long before it plays up. If its a similar time frame you have a fuel flow issue.


If/when you do pull the carb apart, take great care not to loose the little needle that goes above the float on the back of the primer/carb face plate.
Stretch your new O-ring onto it, dont roll it on.


A good known spark plug. Keep in mind that it is not unheard of for a new spark plug to be faulty.
And regular checks for a consistant spark while it is giving issues will tell you if it is ignition related.

Thanks, I couldn't feel any movement in the flywheel and I'll take some photos of the gaps. Should I clean up the surfaces as I've seen recommended in other posts? I plan to clean the connectors where the spade connectors attach but I understand these are only used for shutting down the mower.

I did a search and found this which makes sense.

What is the air gap for the flywheel pole shoes to the lamination stack on the 2-stroke mower?
The air gap is 0.25mm (0.010 inches). Make sure the gap is 0.010 inches on both sides. Check also the clearance at the balance counterweight opposite pole shoes. Balance counterweight should be more � mm than 0.010.

source: http://www.mowerpowerftg.com.au/victa-faqs


Will do, I'll get it back together.


I've used premium for this mower since new, in the what fuel to use thread it has mentioned that using premium can cause some gumming up of the fuel system? I haven't had any problems with my stihl line cutter and they were purchased at the same time. I run both at 25:1 although both say they can run at 50:1.


Thanks, will try that all out tomorrow.


I'll try and pick one up on the way home tonight.


What is the best/safest way to achieve this?

I just went to quote that last bit on the spark and theres all sorts of stuff in that post that didnt come out, like some hidden stuff.

The flywheel & ignition. Dont be anal with it.
The magnets on the flywheel etc, its done with magnets and they do not need clean steel.
Yeah check the stop wire contatcs are not corroded, they should be fine.



To check the spark you clip the spark plug lead about 3mm away from the alloy of the head (use a clothes peg) then in a dark space pull it over and check for sparks.
You would also do the same but with the plug in place if you want to check the plug is sparking.

The smaller peice you are talking about on the flywheel, I'm fairly cretain that is just a counterweight, the gap to worry about is just the one between the core and the magnet (the big one with the split)

As Ty said, the gap must be 0.010-0.012" between the coil yoke and the steel magnet set into the flywheel. No particular clearance is required from the aluminium part of the flywheel, as long as it does not touch the yoke.

Grumpy, I think the confusuion came not from an alloy part, but from a steel counterweight (Pic 4) that opposes the magnet on the flywheel (Pic 5)

To my knowledge this counterweight surves no other purpose (althoug i could be wrong) I have never found it's clearance to be relavent to the function of the ignition.

Well I could have saved myself a lot of work!

Turned the tap on and the petrol just dripped out very slowly.

Removed the brown looking filter and it pours out.

Time to reassemble, fit a new plug and clean the filter! I'll update when it's back together and hopefully all will be well.


As someone else posted further down I was confused with the counterweight, when you said two sides I assume sides of the flywheel!

At least I have learnt a lot more about my mower now!

All fixed, the mower is working well.

Cleaned the filter with compressed air, fitted the new plug, painted the blade base after removing the rust, sharpened the blades and it's working like new again.

Need to buy a new filter as I snapped off the bottom 1/4 of it however can't see one listed in the store?

Thanks to everyone for your help, greatly appreciated.

Hmm it appears there is niether the filter or the fuel tap in the store. While you are going it might pay to replace the air filter. If Bruce doesnt uploadthe filter to the online store you can get them for a couple bucks at your local store, I have a big bag of them from a bulk ebay listing from a few years back.

If you go to bunnings you can buy a whole new tap for $7.

Another common fault is the taps leaking. They leak externally when on or leak internally when off. Both easily diagnosed.

Hmmm well the unit ran fine for me this morning for 10 minutes. After I ran it I noticed I left the cooling shroud off so removed the top plastic cover and fuel tank, inserted that and re-attached.

My wife went to use it this afternoon after my stories of how it now runs better then new but it didn't run for long and became progressively worse and now won't run at all. Looking inside the tank the filter was dislodged when I put the cooling shroud back so I'm assuming that crud has ended up in the carby?

If you didn't clean the tank out before you reconnected the hose with the filter missing, yes, the crud is now in the carburetor's fuel intake pipe leading to the needle and seat. That may be what is wrong. What were the new symptoms of the failure?

It started up but soon after starting to drop revs, I asked my wife to press the primer and each time she pressed it the revs would pick up to normal but progressively got worse (she would have to press it two-three times to get it back to normal) and in the end I said give it up.

I checked and the fuel filter had dislodged. I tried to start it and it wouldn't start at all no matter how many times I primed it. I haven't checked spark however but will do this after I get a new filter/tap from bunnings and clean out the tank.

I don't think you can get anywhere now until you clean out the tank and hose, and fit a filter. When you've done that, it's going to be necessary to clean out the carburetor's fuel intake, needle and seat, primer, main jet, and float bowl.

Do it once and do it right.


I think you are doubting the machinery too much.
You had a fuel problem, and now its playing up again and you are mentioning spark again.


Personally i would not even contemplate removing a filter unless the tap was out of the tank.
Take the tap out. Put your thumb over the hole, put some fresh fuel in the tank rinse it round and shake it all about then tip it out on the nearest weed patch. Get the tank squeaky clean.
If theres even a hint of water, a dot of milky goodness, air the tank out, put it in the sun and dry it out.
If its hot you could also use some warm soapy water. You can stuff a rag in there as well and poke it about with a screwdriver and pull it ouf with some pointy nose pliers.
Bone dry without a hint of dirt or grass is how you want it.

While you are wating you can sort the filter, refit and put the tap back in the tank when its chean and dry. Or just fit a new tap with filter.

Pulled the carby apart, cleaned it out and reassembled.

Picked up a new tap and filter from Bunnings for $5.76, cleaned the tank out and refitted.


Tested and ran for ten minutes with no problems and no leaks. I left it out the back to mow the lawn when it finally stopped raining and this afternoon realised I had left the fuel tap on yesterday and there is a slow leak from the carby where the white plastic cover on the fuel intake with the priming bulb. When I refitted it I had problems as the plastic seems to have deformed a little but it seemed ok at the time.

So time to order the following

https://www.outdoorking-forum.com.au/index.p...mp;cPath=193_514_225&products_id=576

https://www.outdoorking-forum.com.au/index.p...mp;cPath=193_514_225&products_id=578

I think the float needle I need is this one as mine is black
https://www.outdoorking-forum.com.au/index.p...mp;cPath=193_514_225&products_id=582

And I also need to replace the snorkel, is this the correct part for a 2003 VSX160 powertorque?

https://www.outdoorking-forum.com.au/index.p...mp;cPath=193_514_222&products_id=726

The snorkel is the wrong part, that is for a 1970's victa with a G3 carby.

It will flood if the tap is left on even with a new needle and primer cover not knowing how madly warped yours is I would probably use it again.