OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Victa Two Stroke Engines Powertorque won't start

I was using the 600 with a PT on it a few days ago and it stopped and I thought it was out of fuel so I packed things up. I went to put fuel in it this morning and I looked in and it wasn't out of fuel, still had fuel covering the tap. I put more fuel in it and it gave a couple of flutters but would not start. It has spark. I changed float needle, tried a couple of new plugs, tried a squirt of starter fluid, nothing, not a peep out of it. It has compression not excessive but it should run fine as it is. This one has me a little confused as it was working and starting perfectly before it stopped

Norm, would it be a blocked exhaust or port by any chance?

Or perhaps the decompressor blocked slightly open by carbon.

Dunno Norm,

Was this the PT that had a strange noise in it? Maybe this is something to do with that.

All the best
Jeff

Hi NormK,

It's likely to be the starter o-ring which soften and allow the fuel to excape and air to enter during cycle which you lost suction of fuel into the cumbustion chamber. If you're lucky to have purchased this particular starter o-ring that will just soften after couple of used. This o-ring will soften even a day of use and without warning. Of course couple of things to check - diaphragm cover possibly comes off, faulty decompress but unlikely, blocked jet nozzle. As you said, there is a spark, changed float needle and have fuel in the reservoir. Is the spark plug wet or dry during crank? If wet likely to have starter o-ring, if dry likely to be the jet, carby body vacuum issue, diaphragm or fuel supply. Hope it helps.

Cheers,
TheCarbyMaster

Starter "O" ring is new, I haven't had any problems with the ones I have been using, but the fact it won't give a hint of firing with a squirt of starter fluid in the plug hole that is the strange one. This bypasses any of the suction side of the motor and usually is an indication that it has been straight fueled which I know it hasn't. If it wasn't for the fact that it is on a 600 that makes it a bit of a job to change the motor I would have just swapped it over, might get a chance to look at it tomorrow

Out of interest Norm, did you start using a different sort of oil in the mix?

I remember you saying you use regular motor oil in the mix, maybe (hopefully not) the oil came out of suspension in the fuel and straight fuelled it.

Although I find this highly unlikely

Plug wire hasn't worn through and shorting on the head when the plug is in the engine, but not when plug moved checking for spark?

Hi Tyler, fuel is not the problem, I put 4 liters through it the other day and my mixed fuel doesn't last long here either, I go through a fair bit of it. Good point on the plug wire, but I had it on and off several times today and I don't think it would go back in exactly the same spot to short out each time

Hi NormK,

Squirt with starter fluid only bypass the fuel supply into the combustion chamber but doesn't bypass the air since without the air, no matter what, the engine won't fire up. There are five things need to be present to fire up the engine as we knew: fuel, air, spark, compression and timing. One of this if missing, the engine won't fire up. If you squirt with starter fuel but if there's no air going into the combustion chamber during downward stroke, the engine won't start. If there's no air, possibly puffet valve is closed maybe because the control spring pop out or there's a leak in the crankcase o-ring. Timing: I haven't heard PT of any issue with flywheel misalignment but worth checking. Compression: provided the Piston rings are OK, it's mainly the decompresor valve. Hope it helps.

Cheers,
TheCarby

Hi Norm,

Seems unlikely after what you’ve said above, but is the fuel cap venting?

Cheers,

John

Hi Norm,

When you say it has compression, have you hooked it up to a compression tester? Or are you going by feel? Is it possible that the head gasket has blown?

Cheers,

pau13z

Only thing I can do is pull the head off in the morning and have a look see, nothing else I can think of and even then I doubt I will find the cause

How'd you go?

Hi Paul, bore is scored a bit on the exhaust side, not sure if it is recent but I'm guessing this is why it stopped. I will give it a hone to see if it will clean up, put a set of rings in it and see how it goes.

That's a shame to hear, but hopefully the hone and rings will help, fingers crossed. I hate to see a Victa 2-stroke thrown away/destroyed when it's so simple to keep them running forever.

Still though, it's odd. If you're using the correct mix, why would it just all of a sudden stop working?

Specifically for when it cut out (And possibly moments before), were you on a hill/slope? Or were you running on flat ground? If you were on a hill/slope, which side of the mower was up/down?

Have you tried replacing the exhaust? Used a spark tester while the spark plug is installed?

These are the kind of cases I both love and hate haha.

It could be to do with it being mounted to a 600! I read someone saying that full cranks had problems from sideways force from the belt to the blade disc.
I imagine a half crank powertorque suffers even more sideways stress in this application. Yours might have thrown up it's arms in protest!

Yes Paul at times it was up on some very steep angles,probably 45 degrees I was trying to keep the carby on the lower side but could not use it that way all the time.
MF, this motor has done a lot of work so this might have been the last hurrah for the poor thing, I don't think the fact it is a PT that is the issue. I got it cheap because the motor had a strange noise when I tested it.Then I gave it a big kicking by tearing into that massive pile of kikuyu that was also full of rubbish you couldn't see till it came flying out the side.

Maybe the continual operation in that position saw it run a bit lean (sucking air from float bowl not fuel at certain angles).

Or perhaps a build up of carbon in the exhaust port got to the point of causing

Hopefully a hone and a set of rings gets it back

Hi Norm,

Could it be that a bearing has gone? This would explain the noise, and possibly be the cause of the slight scoring on the bore (Misaligned). That said, it wouldn't necessarily explain why it was running, then cut out and wouldn't start.

Being on a decent gradient would explain it cutting out, but not that it won't fire up at all. Unless the transfer port which is normally pretty stacked with fuel is entirely empty.

But to then get not even a single pop when using starter fluid... that's really odd. If you remove the carby, remove the exhaust, spray some starter fluid and you don't get even a single pop (Even if it's weak), I'd say it would have to be the spark. Because by opening the exhaust and intake, you've got plenty of air available and no restrictions, you've got fuel from the starter fluid, and even with almost no compression, you should still get a flame. If you don't, I'd say it's spark related. That could also relate to the noise and scoring mentioned above. If the flywheel is misaligned with the magneto because of the bearings, you could have a spark issue.

Hi Paul; it wasn't a bearing noise, as I explained to Jefffrombrisbane it was a sound I had not heard before, but once I had used it a bit I think that noise had gone, but the poor thing was copping a real hiding doing what it had to do. I will give it a hone and new rings tomorrow and see what happens. I have over 40 motors here that have spark but will not give the slightest hint of firing even with starter fluid. All these motors I test on my test bench using the one carby so that eliminates the fueling side of it and they all test fine with spark and I usually test with the one spark plug so that eliminates the plug as being an issue

Hi,

I can not see how these symptoms could be a piston or bore issue. More likely fuel or crankcase compression. I have had a misaligned flywheel on a PT. The blade nut was not done up tight enough. Ruined the flywheel.

Still needs the motor taken off the base though, probably easier to put another one on.

If you do have to take trhe motor off the base, please take a picture of that factory pulley for me. I would love to see what a real one looks like.


All the best
Jeff