Aerocharger & fuel in motor oil
#1
Aerocharger & fuel in motor oil
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.
Last edited by Springer*; 04-26-2015 at 05:04 PM.
#3
Join Date: May 2015
Location: Then Wisconsin, now North Carolina
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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.
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.
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#9
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.
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.
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Rockhavok (08-29-2021)
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