OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Victa Two Stroke Engines Victa 2 Stroke running hot

Hi,

A couple of months ago I inadvertantly ran my 8 year old Victa Tornado with fouled fuel in it for about an hour, which pretty much killed it. A friend of mine offered to take a look at it, and he replaced the fuel filter, air filter, carby, and spark plugs. Got it back a couple of weeks ago and it started up straight away and seemed to run fine.

However, I shut it off after running for about 1/2 an hour to get a drink, and I came back downstairs, and the motor was smoking and it had melted some of the plastic at the top. There did not appear to be any debris around it or anything that was on fire. I left it an hour and tried starting it again, and it wouldn't start, and the pull was very hard, and I could see the flywheel was kind of seizing a little as I pulled it. Since then I've given the starter a pull, and it seems to pull okay, but I am reluctant to run it until I can work out this over heating issue. I'd ask my friend but he's gone on holiday, and I'd like to get it sorted as my lawns only had a line trimmer going over it for the past 2 months now and is looking a little sorry.

Thanks

Hi Robchap, a photo of the melted area and surrounds will go a long way in helping to identify your problem. If you could post one that would be great.

Its part of the blue plastic on top that is over the starter assembly. Pic shown, unfortunately iPhone pic taken in my shed at night - won't be able to take a pic in the day til this weekend

Hi robchap. From your picture I can see your mower is a Victa 2 stroke, a powertorque engine. I would say there is a good chance that mower has been run on straight unleaded and not 25:1 premix. If this is indeed the case, you may have caused some serious damage to the engine.

Yes Robchap, i have to agree with with rusty.ute, it sounds like you've fried the piston and rings at the very least. The excess heat from the exhaust has melted the plastic caused by the the engine running alot hotter than it was intended as a result of the lack of lubrication. I had one with the same symptoms a couple of months ago. once it cooled down, it would run again, and after 15 mins of running flat out would heat up, causing the metals to bind and stop dead and cease up til it cooled down again.
Pull the top cover off and remove the 2 clips holding the muffler. Once off take a look inside and you'll most probably find lots of scoring on the piston and the rings ceased onto the piston. You can check this by pressing on the ring with a screwdriver, you'll find that thre'll be no give as they've locked into the piston.

Hi Robchap,

I had an almost identical problem with my mastercut 460 a few weeks ago. While I was using the mower, I could feel the smell of burning plastic. I saw then that the the plastic just above the muffler was completely burned. After removing the mufflet, I could see that It was out of order. There was a hole at the rear leaving the exhaust gases to escape. After replacing the muffler by a new one, the problem was solve.
Hopes this will help you.
Regards,
Serge

Definitely hasn't been run on straight unleaded - I've had this mower for 8 years and have managed to never forget to put oil in the fuel, the same fuel was used for three tanks full in the line trimmer right afterwards. Could this have been caused by the fouled fuel?

Will check the muffler and have a look at the piston over the weekend. Question - if the piston and/or rings are damaged, is it worth/possible to fix it?

Detonation is a possibility if run on off fuel,Ive never seen it in a 2T Victa myself.....The over heating does seem odd the mower looks to new to have a hole in the muffler but it may or be leaking..To check for detonation pull the head and look for what looks like bubbles on top of the piston and in the combustion chamber you will have to give them a good clean to see it..Basically it gets that hot in there they strat to melt from pre detonation...but my money is on a hole in the muffler .Cheers

Just in answer to Robchap's second question:

If there's any scoring on any 2 stroke machine it must be repaired as the engine may never run right again and could continually give you problems. If there is scoring on your machine, then it is definitely possible to repair it. It just depends on how bad the scoring is. If you remove the crank pin and slide the piston and Conrod out of the cylinder, this is the best way to see the real damage to the bore. If there is deep grooves in the cylinder you will need a rebore and need to fit oversized pistons and rings, or find a second hand one. But if there is only light scratches and most of the scoring is concentrated on the piston skirt, then a quick hone and new piston assembly can be installed. Only If cylinder is in good condition.

On the other hand you may only have a stuck piston ring, as this is common on a two stroke machine. If this is the case, remove piston assembly and inspect piston skirt and cylinder condition. If no scoring, then just replace rings and clean bore, lubricate and assemble.

Of course the correct way to do it, would be to measure rind end gap and cylinder wear, but for the home owner this is not usually necessary.

You can save yourself a lot of money if you perform the repair yourself. As these engines can be easily rebuilt. Just remember to inspect other parts of the engine (bearing play, o rings) if you decide to strip it and rebuild.

I hope this information is useful to you. It may answer some questions for other members about rebuilding these engines.