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Discussion Starter · #1 ·
1988 case breather. Bottom end filtered to atmosphere. Good oil pressure, fresh oil. Oil tank (when open) and breather have smoke coming out. Took vent hose off and smoke from there and breather. Oil returning to tank OK. Bypass plunger on the oil pump working. Any suggestions on what to look for? Less than 1500 miles on a top end. Went on a short 400 mile trip. Oil lamp came on. and smoking problem started. Went through the S&S oil pump, (gaskets and new keyways) looked OK. Oil looked bad, black. While inside the cam cover changed cam. I sure that the timing marks and breather gear are right. I'm leaning towards pressure being built up somewhere but I'm confused as to how and where. Any help would be appreciated.
 

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Discussion Starter · #3 ·
Thanks for the reply. With only 1500 miles on a stock 80" bore (new cylinders and piston kits from HD) I wouldn't have to worry about this. But then again it wouldn't be the first time I was wrong.
 

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You might have used chrome rings (they take a really long time to seat) or the honing and/or cylinder cleaning might not have been done properly. When cyl.s are honed, it leaves behind a bunch of gritty sandy debris and requires an elaborate process to remove it. If this wasn't done (most shops I've worked at do NOT do this) then your top end will wear out in short order. The grit seeps out into the bore and acts like ball bearings keeping the rings from seating.

If I were you, I would put a bunch of miles on it, and when I hit 1500 or so, I'd do compression/leakdown tests and see how it's sealing. Low numbers would indicate either chrome rings (needing WAY more miles) or a ring/cylinder problem. It's too early to tell just yet, though, so hold off on deciding until you get it at least broken in.
 

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If the rings aren't seated in 1500 miles it ain't likely to happen. My advice is if you want to know why it's smokin' leak it down. The black oil is a definite hint. The Harley rings are a moly faced iron top,iron second and three piece oil control. No chrome.

Not sure why the oil light would come on. There may be more than one issue.
 

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I should know better than to type a response after leaving a screen up too long. I missed your second post. 1500 is plenty of time to seat iron rings. You might want to check if it's overheating as well. I'd check the timing and jetting/intake seals. Hot enough, and it'll set off the light at low revs, and burn up some oil where ever it is. Also, ring gap too small can bind and roast the cylinders.
 

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Sounds like roached cylinders, or worse. Did you check for vacuum leak(s) when top end was done? Sounds like oil got REALLY hot. Put pistons at TDC and with bike in gear and pressurize the cylinders throught the spark plug hole . My guess is you'll hear the blow-by leaking into the bottom end. Are you hearing any knocks or rattles? Let us know what you find.
 

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Do a dry compression test, and then a wet(engine oil, half a teaspoon) one, and see what the difference is. If it is vastly higher, by over 25 lbs or more, your rings are not seated, or failed to seat. The lower end "smoking" is a sure sign that you have blowby from the topend, to the bottom end. It will only get worse, so get ready to tear it down.
 

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Discussion Starter · #9 ·
Thanks for the replies. I'll be expecting to do a tear down after I do a little testing. Maybe I'll get lucky and be able to do a re-ring but with my luck a rebore and pistons will be in order. I appeciate all the suggestions.
 

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I'm not EVO knowledgable, but If the leak down test comes back OK, I'd look at the oil breather next. You could be off a tooth or two, but then again, if it started after 1500 miles, it does sound more cylinder related. It'd also smoke from day one if the rings were put on upside down too I'd think

Sixball
 
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