So after burning up 2 pistons and several posting on the forum and everyone's help.
I took the pistons to the dealer and the mechnic said that there is water getting in
the cylinder. I checked the head it was fine, the cyclinder has a small hole
right above the exhuat port, looks like it belongs there.
Not sure how to check where the water coming from.

Also if anyone in the Philadelphia area show would be interested in buying this quad as is. Please contact me

Thanks
TUT

 

On supercharged cars we use water injection to cool the cylinder temps so water won't cause a piston to "burn" up. Only a lean condition would do that. What kind of bike is it?

 

it is a polaris 99 400 sport.

 

Is it a 2 stroke?

 

yes sorry.
a little history.
this quad is all stock. never had any issue. rode in february and it shut off
i took it apart and the piston had a hole in it.
put a new piston in it and the same thing happen in about 15 minutes of running.
at first i thought it might be the oil injection.
but the other post that i have on this site eveyone says i might have a air leak.
i took the carb apart cleaned the jets
checked all the boots nothing is cracked.
that is when i took the pistons to the dealer was told water caused it.

so it is 90% together with a new piston. but i don't want to start it until i track dwon the issue

 

Yes it could have been an air leak but if you checked the intake boot from the carb to the motor and it's not cracked then that's not the case. A lean condition won't burn a hole through the piston in 15 min but if the oil injections not working right it would. Something else that would cause one to go very lean is the crank seals where the crank goes through the case behind the clutch and flywheel. If those seals go bad on a 2 stroke the engine will pull air in and go lean. I'd start by manually mixing the oil in the gas before you put it in the tank so you know you have the proper mixture. Then start it up and run it for just a few min and pull the plug. If the tip of the plug is white then you have a lean problem and not a oiling problem. If the tip is golden brown then you know the oil injection is not working right.

 

To look at the seals i have to take the clutch and the flywheel off?

I guess i can put it all together and do like you said about checking the plug.

after i replace the piston, i did mix the oil and gas but not to the 32:1 (which is 16oz to 5 gallons correct?) and it was running pretty good and i did check the plug and it was oily. then i poured more gas in and no oil. and when i took it apart the plug was white/gray.

thanks again for you help.

 

Yes you would have to take the clutch and flywheel off to check that but that would be the last thing I'd check. So you did mix the oil last time and it still burnt another piston?

 

i didn't mix it to the right ratio, big mistake on my beahalf.

but i had it mixed then i added more gas. i was blowing a lot of
blue smoke, then that stopped and the quad coolant heated up

but by then the piston was shot.

i was thinking about changing the jet to a larger one.

i guess i can put it back together, mix the fuel the right way let it run for
a little and pull the head and check the piston.

 

Make sure the automatic oiling system is unplugged when you do that. Mix the gas the way it's supposed to be and run it. Then just check the plug. You don't have to take the head back off.