I have 1993 FXSTS with a intercooled Aerocharger turbo and it is getting fuel into the motor oil. I put the kit on in 1994 and it has been great until recently. The bike runs fine and you would not suspect a problem without looking at the dip stick. I have checked most everything that I can think of that would cause the problem. The fuel pressure regulator diaphragm is good and I cut the fuel pressure to 4psi. The cylinder compression is 155 both front and rear cylinders. It is running a Mikuni carburetor and I have had it apart but found nothing visibly wrong. The spark plug reading is good and like I said the bike runs great other than the fuel oil mix. I do not have a boost gauge on the bike so I do not know what the boost is but nothing has been changed in 21 years. Has anyone had a similar issue or have any thoughts about what could cause the problem? Yesterday I put fresh oil in the bike and left it on the low side. In 20 miles it was over 1/2 of a qt higher on the dipstick and you could clearly smell gas in the oil tank.

 

I would have thought buggered rings, but if the compression is good? What about a leak down test?

 

My initial thought is rings and a wet compression & leak down tests might be telling - especially after 20 years of boost on an air cooled motor. Perhaps they are not sealing well under boost pressure.

My second thought would be a heavy float (if it's not the sealed plastic one), or something allowing the carb to dump fuel - even a bad needle/seat seal.

Has the main needle worn a notch into the guide after all this time and boost?

It sounds like you checked for fuel in your regulator line. That's a lot of fuel in 20 miles so it;'s surprising it's not jumping out.

 

Sounds like your running it too rich.I'd get it on a dyno and see where your at with your AFR.You'll end up washing the rings out if you don't.

 

Another one post wonder by the looks of things!

 

So!!! It seems legitimate. Maybe they guy Googled for help, and found this forum.

 

So!!!! Common curtsey to let folks know its resolved and what the fix was. I reiterate...A 1 post wonder.

 

What the heck is a Trike Guy doing over here on this thread?LOL

 

I am not a one post wonder. I have been out of town for two months and I have also lost interest for a while due to the extreme heat in Arizona, 116f recently. I don't ride the bike much when the temperature is over 100f.

Next week I hope to have the time to do a leak-down test. I am also going to install a boost gauge on the bike at that time. I will post my findings after I do the testing. The bike is a 1993 but it only has 7,00 miles on it. It has been well maintained and never abused. Thanks for the suggestions on the cause.

 

Welcome back! keen to see how things pan out on this.