I have an 01 sportsman 500ho.. there is a line that enters the airbox on the "driver" side that is blowing oil into the airbox, saturating the air filter, thurs making the engine run poorly. It only happens at high rpms and/or high load. This tube comes from the engine next to the oil tank inlet/exit lines. The dealer tells me my oil is overfilled... the dipstick reads "add 8 0z" and I've tried bleeding more air out of the system through pinching the vent line-- this line will dump about 1 pint in less than an hour of riding on hills.

Any thoughts? Perhaps the oil pump?
Thanks!

 

It is overfilled with oil. Make sure to check the oil properly. Start cold engine for about 30 seconds and then check.

 

The oil is not overfilled-- it reads on the low oil/add oil mark-- the dealer asked me the same thing.
I've read some other posts that suggest it could be the rings. This comes as a surprise because I just had a new top end put in 20 hrs ago.


any other possibilities?

 

The only two thing that I can think of that will cause this is:

A. You have too much oil in the engine.
B. Your ring seal is so bad that a ton of combustion gas is getting past the rings and pressurizing the bottom end which lifts the oil up and through the breather hose.

You said it's not A..................so that only leaves B.
Take a leak-down to confirm.

 

K thanks...
I don't have or know how to do a leakdown, but I did a compression test today.. twice .. and only got 30psi. I don't usually run it that hard so maybe I wasn't missing the power? Is it possible to run on only 30psi? (I thought an engine needed 60+psi).

comments?

 

I had a two stroke that only had about 50psi and it ran. When it got to around 30PSI I could not get it to run any more.
Time for a tear down. Something got screwed up on the rebuild or your not running an air cleaner. [img]i/expressions/face-icon-small-wink.gif[/img]
Sorry dude.

 

are you sure the ring slots arent lined up when they got put together? maybe not honed. but you should have way more compression then that. usually if your getting oil in the air box thru the carb. i think you would have way to much crank pressure. is it vented? just my 2 cents

 

okay... apart and back together.

the rings were aligned properly, but the gap was about 3/16" .. instead of <0.039. I checked the bore, it was still round and the top, middle, and bottom showed no signs of warpage or uneven surfaces. I put a new set of 020 rings in it and it runs great again.

What i don't know.... is how it happened.. the rings were worn very badly. Did they not seat properly?? ..? or were they the wrong rings (010 over rings will almost work, i checked before i ordered the 020 rings). I wonder if they never seat properly?

I'm open to input on those questions-- I figured they never seated right or i had a "bad" set of rings. I'll have to see what happens with this set. I only had ~20 hrs on it from when it was bored 020 over... and I'm sure it was done correctly (honed, ring gap, etc).

Thanks!