OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Victa Two Stroke Engines Help with Victa killing spark plugs

hey all,

having an issue with this mower. It will burn out a brand new spark plug every use. Turns the plug black and once the mower stops, will not start again. Put a new plug in and its away.Have tried winding back the amount of oil in the 2-stroke mix to below the suggested amount, and still fouls up every plug. When on full throttle it does not blow any smoke, but when throttle is pulled back to the 'start' i believe where it drops the rpm down for catcher emptying, it blows white smoke. Any suggestions?

Fuel kills the plug, how you can lean it out I don't know. How do I know this, I rode around Tasmania a few years ago on an Enfield, had to keep buying plugs in a sixpack, nobody had any idea what was causing it, got back home and dropped the needle one notch and solved the problem. Motor ran fine through all the rev range and then for no reason it would just stop and you could not reuse the old plug. How is the aircleaner,if it is a bit clogged it could be causing it to run rich

Do you have any pictures of a plug (or several) after it has been used in the machine?
Is it possible that the new replacement plug works as the machine has cooled down sufficiently, after it has stopped between changing plugs, that it may be hiding a different issue to what it appears to be?
I am working on a similar engine that is running that hot, it has melted a hole in the cowling above the muffler. I am looking at changing the position of the Poppet Valve from A to C to richen it up and have just uploaded a photo of the spark plug to the Post "Power Torque muffler getting hot. Melting Cowling".
Not being a small engine mechanic myself, just a few thoughts from reading about different issues I have had on various mowers I have been working on.
Daryl. :-)

Just noticed this is in the "Victa Lawnmower Frames" section and may be better if it was in "Questions on Victa Two-stroke Engines" instead. Maybe a Moderator could change or advise???

Firstly check your jetting. Sounds like your running either too rich or too lean. (Both will turn the plug black for different reasons (And look different). If you post a picture of the plugs we'll be able to tell you what the reason is.

NEVER change the premix though - You're asking for trouble changing that (With the exception of some very old machinery - I run a series of seagull outboards on a 16:1 mix rather than original 10:1 suggested as the oil today is far superior than that of previous times).

Reset your oil premix and post a pic.

Also I believe I'm correct in saying your poppet valve should be set to "C". Try changing that and then have another look.

Is your engine hard to start to begin with? Could be an air leak which would cause the engine to run lean (Too much air getting in and "Diluting" the fuel mix. Could be as simple also as a blocked air filter causing too little air and inturn running rich.

Also silly question but you're using 2 stroke oil not 4 stroke oil in the fuel right? and small engine not outboard oil?

All this aside though we need a picture of a fouled plug to advise.

Thanks,
Pete

First things first.whenever I have to work on any 2stroke machine that has a problem. Remove exhaust and see if piston is scored,looking through exhaust port. A scored piston and rings depending on severity,will still start and run .but due to incomplete burn ,due to blow by will fowl plug . If all good,as stated previously check air filter.Those G4 carbies can take 2 different sized fuel needles.black and yellow .Black is shorter than yellow and therefore will raise fuel level in float chamber. I have never ever seen,in all my years as a small engine mechanic specialist ,working only on outdoor power equipment.a lean running engine produce a black plug.In that case they are grey/white looking.

I agree with most of the above. In addition to that check that you have the correct jet in the carb. Your engine is a VSX160 and should be using the jet with the 2 rings on it.

Sorry to clarify no a lean engine doesn't turn the plug black BUT if someone inexperienced is looking at an obviously discoloured plug just gets told if it's black its running rich, they look at the plug and see it's grey they may take it as being black. this is why I asked for the photo. Not very well explained but for someone new to reading plugs it can be hard to tell black from grey with no comparison.

Pete

Just out of interest how are you mixing your fuel ? I only ask as there was a recall on oil mixing containers that were all marked incorrectly by our Chinese friends. 25:1 fuel mix is 40ml of 2 stroke oil to 1 litre of fuel. Have you had the machine from new ?

gday mate. what revs do you run it at? it is my understanding is that if you run a 2 stroke on half revs it doesnt burn the oil in the fuel and will foul the plug. hope this is of some help
sean