i purchased a new 01 trx350fe ex that now has less than 1300 miles and the engine started smoking while riding. back in the garage i also discovered about 1/2 cup of oil in the air filter box.
i removed the head clylinder and rings and gauged the oil rings at way over 1.0 mm and they were worn uneven more on one side than the other also true with the compression rings. i carried the clyinder and piston and rings to a honda dealer and a performance motorcyle shop. the dealer said the wear is caused by running without a air filter or a very dirty filter- never-- never ran without the filter and cleaned the filter 5 or 6 times since purchased. the motor shop thinks its a oil problem and recommened 20-50 motorcyle oil which i bought. i had been running 10w40 castrol and have changed oil and filter around every 150 hours. the oil level was maintained also.

i've ordered new rings- the piston is ok -- but i don't have a clue what caused this. the clyinder is ok for the standard rings and piston. also i thought about oversizing the piston until i found out only honda pistons are avaiable for the 350 instead of the wiesico piston kits. how much does oversizing the piston help with the power?

this is my first posting ever and i am in bad need of some advice before i put this back together

thanks,
daddymac-

 

oversizing the next size up will not give a noticable increase in power, but it allows you to start with a fresh piston, rings and cylinder bore. make sure you hone the cylider too before you put it together, and washt it out with hot soapy water after you hone it. I'm not a fan of Castrol oil. 10w40 is fine for oil weight, but you should try Amsoil Motorcycle oil that's made for atv's and wet clutches. You should also clean your air filter and oil it with the right kind of oil, like honda air filter oil or other good quality foam filter oil.

Then you see if you could take the oil pump apart and measure it to make sure the pump isnt all worn out. maybe there wasnt enough oil pressure to get to the top end??

 

thanks for the oil pump tip i'll look into that--

whats your opinion on Golden Spectro 4 Synthetic/petroleum blend 20w50-- it's what the motorcycle shop recommended

 

Many of the 350's from those years I have torn down because of the problem of filling oil in the air box have had the same strange problem that I find abnormal. Many of the rings have not had a mark on the end of ring gap, that lets the installer know which is the top side when installing. Is it possable that Honda had a bad batch of rings that were installed backwards ? HMMM Or did they chatter so much that the marks were worn off ?
I asked them once when I called tech line. bringing up my point and was basically told I was full of crap, and I should put 5w-30 oil in it because the oil is being transfered into the air box via the crankcase hose on the right rear of the engine.
The units I have put in the 5w-30 still come back and have oil in the air box
After re-ringing the engines, I have no sign of oil in the air box the next time thay come in for service, once again, HMMM


----- Gimpster -----

 

Hello community. I am new to this website and wanted to reply to this thread. I am a new atv owner, and i have the exact same problem as described in this thread. My 01 honda rancher 350es is sitting at the local honda dealer and they're telling me that the oil is shooting out of the crankcase breather in the filter box. no one there has any idea about why this is happening and then i saw this thread and felt the need to join and ask questions. so if you can help me out i would appreciate it. again here is what is happening, oil from the engine is exiting the crankcase breather and filling the filter box up??? why would this happen and what if anything is causing this? the compression was checked, it was great, the rings were just replaced on it from previous owner. wondering what i can do and if it is just easier to buy a USED TRX350FE motor from somewhere out west??? anyone than can help me get started looking, just let me know where, or what i can do about this motor which according to the HONDA dealer its at right now is actually in great shape. problem is they want 1200$-1400$ to just tear it apart, and the there is parts and more labor....HELP!!!

THANKS,
newatvguy11