Why would a piston fail on a 2 stroke kit

K

Khalil Brooks

Member
It’s essentially in the title. Yesterday I blew my piston and I’m just curious about if the piston reached the end of its life, or if there are other factors that can lead to piston failure. I ride about 60miles a week and I’ve had it running about 9 months
 
I think running lean, running without back pressure in the exhaust or at full throttle for extended periods of time could put holes in the piston.
 
Do you know more about why running lean could cause that, and would the lack of back pressure relate to running lean or is it it’s own separate issue?
 
I don't know much. Running lean and the lack of back pressure in the exhaust cause the engine to run much higher than its normal temperature range. I think the increased heat burns holes in the piston.
 
If you damaged the piston you will need to replace the cylinder as well, also take the engine off the bike and wash out the debris that fell in the crankcase. I use mixed fuel to flush the crankcase, you can find a top end kit from the vendors on the forum or on eBay.
 
I run 32/1 on all of my 2-cycle engines no matter what it's on, bike, chain saw, blower etc. I'm still running the same piston on my original bike engine that is now 10 years old, if you get it tuned correctly it will last if you don't abuse it.
 
Not completely true many factors can cause that, wrong gas mix, wrong spark plug heat range, duration of high rpm runs,to long a plug, wrong squish hight, poor cooling of head, some fuels with additives put in them can damage aluminum. Ethonal can cause aluminium to degrade over sitting long periods, but as far as end of life? No reason under correct use it should ever have hole in the top of it. There is some bikes or motors in general 40 years old run fine that are correctly set up and cared for
 
Probably a problem from running lean. These little engines depend on a slight rich mixture for cooling the internals. A picture of the failed picture would help. Oil mix won’t burn a hole in the piston but can hurt bearing life and scuff up the piston and seize rings if it’s too little oil.
 
A lot of oils will “work” but not as good as a oil formulated for air cooled two strokes. I mixed straight 30w at 6oz per gallon in the 70’s for a 250 Bultaco, It ran but would foul plugs, sometimes you have to run what ya got!
 
I been thinking eco friendly lately what would you guys say to using vegetable or canola oil in a 2- stroke bicycle engine...... Like in case of emergency!?
 
Well I certainly think that would likely cause an emergency for you engine.Haha. I do know that they replace hydraulic fluid in machinery with vegetable based oils when they are operated in some very sensitive areas so there may be a plant based substance tha could work.
 
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