Excessive crankcase preasure on my honda trx350fm atv pumping oil into breather box about half qt in 15 mim. moter run good no smoke

SOURCE: fuel gushing

I'm gonna go with theory #2 sort of. My guess is that one or more of the float valves is leaking causing the gas to overflow into the crankcase. This happens often with bikes that are allowed to sit for long periods with gas in the carbs and tank. A thorough fuel system cleaning is what it needs. I'd say go ahead and buy four carb rebuild kits for it - may as well since you'll have to disassemble the carbs to clean the gum and varnish out, which is really the best thing for it at this point. I wouldn't try to run it again 'til you get the carbs to quit leaking, the fuel drained out of the crankcase and put fresh oil in. ,,,

SOURCE: Engine running rough

sounds like you need new rings

SOURCE: crankcase breather

If the bike sits for a while, and then you run it and shut it off, it will drip.. run it more often.

SOURCE: 89 Harley FLTCU oil coming from the crankcase breather tube and

This is an age old problem for the Harley engine. In you 89 model, the crankcase breaths from behind the oil pump through a tube that runs to the backside of the air filter assembly. Most people that I know, simply remove the tube coming up to the air filter and block the hole in the air filter assembly backing plate. At the breather, they run a short hose to just behind the transmission and cut it off there. This is similar to the earlier Shovelhead engine and the way it breathes. In 1994, Harley went to the "head breather system" which was better but it still gets oil into the air filter assembly.

There is one thing I saw on the aftermarket assessories market once called a "CatchCan". The breather tube ran to it and it seperated the oil from the air and the held it in a small container to be emptied on a regular basis. I have never used one nor have I ever seen one so all I can tell you is what the book said. Matter of fact, I cannot remember where I saw it now. Custom Chorme catalog, maybe. Good Luck, Steve

SOURCE: oil comes out the crank case breather tube engine

IS THIS A 4 STROKE ENGINE? DID THE BIKE FALL OVER ON ITS SIDE FOR A LONG TIME? A PLUGED UP FILTER IN THE AIR FILTER BOX,OR A POSITIVE CRANKCASE VALVE PLUGGED UP? THE CRANKCASE VENTING,VAPORS NEED TO GO INTO THE AIR INTAKE AND BURNED IN THE COMBUSTION CHAMBER CYLINDER.