Picked up a 90 cbr 600f. The bike runs excellent. Idles better than my triumph. sounds great, has good power. But, we have some problems. I think it needs valve seals. It smokes for a breif moment at start up, which is fine by me, but once its been running a bit it litterally drips an oil gas mixture from the exhaust. The oil in the bike, is the color of gasoline and about the consistance of gasoline. I say valve seals. What do you think?

 

i would check to see if an aftermarket jet kit has been installed.
pull the plugs and look to see if they are really black.
to me, it sounds like its running really rich.
i would also check the float height, that can also cause it to run rich, and also leak into the cyclinders, into the oil.

 

Im almost positive theres an aftermarket kit. It has yoshimura exhaust, even runs fine with the exhaust off.

 

Do you leave the fuel tap in the on position when the bike is parked? If you have something holding up a needle(float sticking open) gas may be leaking into the crank and diluting your oil. If the oil smells like gas change it right away.

 

i would start with looking at the plugs.
try and remove one as soon as possible after a full throttle run.
idealy, full throttle to near redline, kill engine, coast to stop, remove plug.
i bet you will find it black, and wet, indicating richness.
could be; 1) dirty air filter, i would recomend a K&N since it has an aftermarket exhaust. 2) jetted way to rich, causing unburnt fuel to exit exhaust. 3) incorrect float height causing rich condition.
gas is getting into the oil from the carbs, not from valve guide seals. valve guide seals will cause smoke at startup and deceleration. unless you feel like completely rebuilding your head i dont think you should change those.
you could also have a bad needle and seat, allowing the carbs to leak gas into the cylinders.
i would also make sure you turn the gas valve OFF, when you aren't riding it.

 

My f3 was wonderful. this bike isnt actually mine, its my buddies first bike. A guy I know bought it awhile back, for his girlfriend to ride. He cleaned/synced the carbs,checked the valves, did a tune up, new tires, and a few other misc things. His girlfriend lost interest and its sat since. He drained the tank, and carbs and it sat for the last year. its got 29994 miles on the clock.

 

Another thing, the rich mixture explains the fuel in the oil, but what about the oil dripping from the exhaust?

 

is it oil dripping from the exhaust? or is it really gas, that is dark in color? its probably gas mixed with carbon from the exhaust, ie. running rich

did you run it with just the muffler off, or the entire header?

 

its oil. it stained the heck out of my driveway. I'm getting ready to go out of town for a four day ride on thursday so I will get back on it when i get back home. Does anyone know what size spark plug socket i need?

 

I have an 89, and experienced a very rich running condition due to who knows what... while trying to troubleshoot, I was playing around with plugs, etc and letting it run on less than 4 cylinders for a moment or two in the driveway - the same thing happened to me, where unburnt fuel was coming out of the exhaust (sounds like a lot less than yours, though) and was mixing with the soot in the muffler causing a black stain below the bike as well... but I never really felt it to see if it felt oily.