acceptable evo compression 85 flhtc.
Club Member
Joined: Jun 2007
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From: Bedford UK
Not sure which stroke is most important, but 130 on both cylinders sounds fine to me, the fact they are the same being good. The performance of the engine at steady speed is what matters, less so at initial cranking speed, I would have thought.
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Joined: Jan 2015
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From: Sandy Eggo's North County
If it has the stock camshaft, then 100psi (dry) might be ok for another 40 or 50,000 miles.
Using a quart of oil in 600 miles is alarming though. No doubt, it is using some, but how much really? This needs to be investigated. Find a way for the breather to recirc back into the sump. This will help you find out how much oil is getting past the rings/guides. Your sparkplugs may tell you also.
Using a quart of oil in 600 miles is alarming though. No doubt, it is using some, but how much really? This needs to be investigated. Find a way for the breather to recirc back into the sump. This will help you find out how much oil is getting past the rings/guides. Your sparkplugs may tell you also.
Club Member
Joined: Mar 2009
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From: Niles Canyon Ca.
Don't worry so much about compression, either you or a shop do a leak down test on her. That's tell you more about the overall engine condition. And keep in mind with an older high mile motor like yours you do a fresh upper end within a year the rods or wrist pins usually start knocking. Think of it like 2 fighters going 10 rounds evenly matched then a fresh guy steps in, tired dude is done in short order.
Stellar HDF Member
Joined: Mar 2017
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92 Fxr, Andrews 23 cam around 30 k at test. First test cold throttle wide open, air cleaner on 150psi front and back, redid hot same results.
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Joined: Apr 2007
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From: Brighton, MI
140 both cylinders, 1994 fxds 36,000 miles. Stock stage 1. That is cold, air cleaner off, slide on the carb propped wide open and throttle wide open. Cranking till the needle stops rising.
Cranking till the compression gauge needle stops rising, with the slide and throttle wide open is the way to check.
Yours sounds fine. Regarding oil consumption, If your year has them, maybe your umbrella valves are shot (or are you a bottom breather?), they get hard with age and don't do what they are supposed to do. The other culprit could be valve stem seals. They get old and brittle also. YD
Cranking till the compression gauge needle stops rising, with the slide and throttle wide open is the way to check.
Yours sounds fine. Regarding oil consumption, If your year has them, maybe your umbrella valves are shot (or are you a bottom breather?), they get hard with age and don't do what they are supposed to do. The other culprit could be valve stem seals. They get old and brittle also. YD
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Joined: Mar 2006
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From:
140 both cylinders, 1994 fxds 36,000 miles. Stock stage 1. That is cold, air cleaner off, slide on the carb propped wide open and throttle wide open. Cranking till the needle stops rising.
Cranking till the compression gauge needle stops rising, with the slide and throttle wide open is the way to check.
Yours sounds fine. Regarding oil consumption, If your year has them, maybe your umbrella valves are shot (or are you a bottom breather?), they get hard with age and don't do what they are supposed to do. The other culprit could be valve stem seals. They get old and brittle also. YD
Cranking till the compression gauge needle stops rising, with the slide and throttle wide open is the way to check.
Yours sounds fine. Regarding oil consumption, If your year has them, maybe your umbrella valves are shot (or are you a bottom breather?), they get hard with age and don't do what they are supposed to do. The other culprit could be valve stem seals. They get old and brittle also. YD