FCR - Oil smells like gas

I've noticed a gas in oil smell recently on the DRZ and I'm trying to track down why.  The petcock checks good but even if it weren't I have an FCR39 (slant) carb that SHOULD overflow any extra, right?  The bike runs fine, is not using any oil, and the oil level hasn't increased at the dipstick.  I do ride it hard offroad and it's typical that it ends up on its side once a ride or so.  Should I be concerned about bigger issues lurking or is a little gas in oil normal for a DRZ ridden this way?


Is there some float adjustment that could cause this on the FCR?  I'm definitely going to check the overflow line to make sure it isn't blocked but otherwise where should I look?


More info: Bike has 20k+ miles, but runs fine.  At last valve check valves were in spec but exhaust valves were on the tight side of spec (1500-2000miles ago).  Need to check again soon to make sure they aren't moving.

Other than checking the overflow line, I can't see any reason for gas in the oil.  No, it is not normal to have gas in the oil and no dumping the bike really would not put gas in the oil.  Float can be adjusted but hight fuel level will just overflow assuming the overflow is functioning. 

That's the same conclusion I've come to.  Seems pretty odd.


I'll prob change out the petcock just as a precaution.  Maybe the float needle needs changing, too.


When I clear the fuel line and turn it on 'prime' to refill the line the carb will drain a few drops of gas and stop.  Maybe the needle is slightly worn and needs a little fluid to seal.  Still don't understand how it could find its way into the oil.

We had the problem of the stock petcock shunting gas directly through the carb and into the crankcase. We thankfully had a spare petcock (still stock, have a Raptor petcock coming just in case) that replaced/fixed the broken petcock. We also had a sticky float needle and gave all carb components a thorough cleaning. Bike is running great now (fingers crossed!) so I'd switch out that petcock as a precaution, make sure everything in your carb is clean and corrosion-free, and see what happens.


My $.02 at least. Good luck!

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now