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[Dean]

Recently rebuilt the top end of a 2004 bullet. Bought a refurbished head, along with new cylinder with matching piston/rings. started up OK but was running rough. Noticed oil coming out the exhaust port of the head, along with bluish tint to exhaust vapors. Plug looked like it was burning oil. Thought it may have just needed to run a bit to set the rings, but it didn't resolve. Took the head off and there was a small pool of oil on top of the piston in the indent where the exhaust valve matches up. The head looks fine. Cleaned the oil off the piston and turned the motor over several times and noticed oil collecting on the cylinder wall above the piston. Figured the rings may be the issue, so I took the cylinder off and the rings are intact and the cylinder wall is pristine. Nothing looks wrong, but I don't want to put it back together if it is going to do the same thing. Could the rings be the issue, even though they look OK? Ordered a new set of rings just in case, but would appreciate any guidance. Could the rings have been installed wrong by the factory? Almost seems that the lower oil scraper ring isn't doing it's job. Where else could this oil be coming from?

[Tim NZ]

Your rings wont seal the bore with the head off; they require pressure on them to effectively seal the bore, in fact, they will pump oil up out of the cases! Unless you have damaged the first set of rings, return the ones you have recently purchased.


You have not said why you have replaced the barrel and piston, and what was wrong with the old head?


For there to be oil being pumped out the exhaust port, the motor has wet-sumped. Drain the sump of the excess oil.


If the motor wet-sumps all too often, you need to look to the fit and finish of the feed oil pump disc and its seat inside the timing cover...


If the scavenge pump is not returning all the sump oil back to the tank, then too your motor will smoke.


For the scavenge pump to be not working at 100% efficiency implies that the pump disc and seat have been scratched, which usually only happens AFTER the motor has had piston or bearing issues?


Don't get all anal about ring gap locations, as the rings rotate around the piston in service and the gaps will line up from time to time on a regular occurrence.

[Dean]

thanks Tim - have heard the term "wet sump" but what actually occurs during this phenomenom? the original cylinder was scored, as well as the piston and the exhaust valve and port were fried. lower end seems OK

[Dean]

Tim, one more thing - how do I drain the sump? Do I just disconnect the fitting in front that goes to the lines feeding the head? How do I insure this doesn't happen again, after I put it back together? thanks

[Dean]

found the post on wet sumping - thanks

[Tim NZ]

Get a copy of the Owners hand book and or the Work shop manual, neither are much good but are better than nothing....


To drain the Crankcase, as opposed to the oil tank, there is a large hex nut underneath the motor, forward.
A similar hex nut that screws up into the bottom of the oil tank to drain that...


The Y pipe to the head is the oil return out of the crankcase, which in turn drains down into the timing chest, which fills and then overflows back into the oil tank.

[Dean]

will feel a bit foolish having torn the top end off if it was a simple fix - but better safe than sorry, I guess. will let you know how it turns out - thanks again