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Engine Mechanical TopicsDiscussion for motor builds, cams, head work, stripped bolts and other engine related issues. The good and the bad. If it goes round and around or up and down, post it here.
2000 Fatboy, 88" with 75,000 miles. Andrews 26 cams. Been working on the rear cylinder since Laughlin. 150 CCP on the front cylinder and had 120 CCP on the rear. Had a valve job done and re ringed the rear and still only had 130 CCP on that cylinder. Adding oil gets the CCP to 165, so I tore it down and tried honing and new rings again. After 70 miles on it, I have 120 CCP.
I just got a set of free cylinders, rings and head gaskets. My question is, should I put more miles on and see if the rings seat or just tear it down again and swap the cylinder. I can't imagine the CCP coming up 30% more after break in. It runs bad at high RPM and I want it fixed.
Thanks!
Any chance your rear cam is a tooth off? What about your pushrods, are they adjustable? If not maybe you have intake and exhuast pushrods installed opposite? Have you added compression releases? Maybe have a leaker?
Last edited by ridedaddy; Dec 9, 2014 at 01:15 PM.
Well, now that I go back thru my logic, the reason I am thinking the rear cylinder is bad is because if I add oil to the cylinder, the CCP jumps up to 160. That's why I did a re ring.
If the cam timing was off, it shouldn't make any difference....Cycle Doctor did the valve job so it isn't the head...
With just 70 miles on it, I don't want to tear it down again if the rings will seat in, but I am skeptical that I am going to get 30 more CCP...
I've honestly never checked one that soon after rebuilding one. Usually look at comp numbers at 1000 miles on them as they should be good to go by then. Shouldn't really be off as much as yours are though either in my book.
Leak down test is next step. With 75K miles, I would be thinking cylinder to piston fitment was the issue. Cylinder taper or just normal wear, particularly if the fitment was a bit on the loose side from the factory. Could be just the result of poor cylinder/piston fitment from the factory that is now exhibiting.
Thanks Griz and djl. I will hook up my gauges and do a leak down. I have a set of take off cylinders and will swap the rear if the test confirms the rings. Then I will have a set of jugs that I can get bored when I am ready to go to 97"
Without tearing it apart of spending more money, a leakdown test will confirm if it is getting past the rings, intake valves or exhaust valves, on either the front or rear cylinder.
If it is sealed up tight, with little or no leakage, then the cams are off.......
Scott
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Low compression issue
