Hi,

I have just done a top end re-build, (2 months ago) to cure a rear gasket oil weep on a 1986 FLSTC. Replaced all gaskets, honed cylinders and fitted new rings, (standard) and the only other thing I did was fit an EV27 cam.
Bike runs fantastic, have been riding it regularly since, idles fine and no strange rattles or knocking sounds.
But, it smokes badly on idle and seems to use a lot of oil. The smoke is definitely oil as I can smell it. Do not know exactly how much oil it uses, but after a 2 hour run, fast motorway and slower twistys, it needs a good top up. Before run oil would be top of dip stick, after run it would be no more than half way up , but people riding behind say it is not smoky. Level would be checked with bike upright.
Did compression test and both pots read the same, approx 165ftlbs, so assume it is not rings or a badly seated valve. As it is an 86' EVO, it does not breath through heads, so no mushroom valves in heads, it breaths through crankcase into open air through a breather filter and not back through the S&S carb, and there is no excess of oil in either the filter or carb area.
I am assuming it is the valve stem oil seals, as these are the only items I did not fit myself as I did not have a spring compressor so I left it to my machine shop.
Before pulling heads again, just want to know if it could be something else, so any suggestions appreciated.

If I do have to pull the heads, can I do so without fitting new base gaskets, in other words, leave the barrels in place?

Thanks,

Tony.

 

i'm gonna by no means presume you don't know what you're doing...because it sounds like you do....but i gotta ask

did you space the rings properly?

and to answer your question about the base gaskets....it depends... what kind did you install? ...that is, were they corked/paper material or all metal like the Cometics? ...if it's the former, i'd suggest you change them, if they're the latter (metal) you shouldn't have to

 

A cylinder leakdown test would tell you the rest of the story. Generally I believe the say 10% leakage is about the service limit for an average street machine. This would tell you if you've got a valve not seating, or leakage by the rings, or neither (which would point towards your valve seals).

I went through something similar on my 98 a few years back...if you dig around, you'll find pics.

To sum it up, I installed an EV-27. Bike started smoking. Turned out to be the exhaust valve seals. When I pulled the exhaust I could see quite a bit of oil in the exhaust port of the head. All we could come up with was that there was a very small change in lift which put a previously untouched parts of the valve stem through the old seal cause a leak.

I tore into the engine, got a bunch of head work done, bored a little, new springs / seals... Put her back together and it was still smoking. This time it was the rings not seating.

Tore into it again, replaced all of the gaskets again as precaution, had been a month and I didn't want to tear into it again. It's been good for er 30,000 miles now.

Hope you get it fixed on your next try.