Leak down test.
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Intermediate
Joined: May 2017
Posts: 41
Likes: 1
From: Reno, NV
Leak down test.
I have a 1997 Road King. Stovk magneti morelli intake. Over last summer I put about 5k miles on my bike and my friends complained about the smoke when they road behind me. I couldn't ever see any in my mirror I did go through a quart of oil maybe a tad more. I performed a cylinder pressure test and neither cylinder performed a 90 PSI or above I was at 60 PSI in the front and 80 psi in the back. I then warm the motor up and performed a leak down test my front cylinder at 80 psi held pretty much right at 80 psi and my rear cylinder had a 3% loss which is in the 10% range and good. Now I left wondering why my bike spoke.
last summer I did have a new cam bearing installed new rings and new valves
last summer I did have a new cam bearing installed new rings and new valves
Last edited by Mhoffer; Mar 1, 2018 at 07:31 PM. Reason: Not finished
Seasoned HDF Member
Joined: Dec 2005
Posts: 19,830
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From: poway
If leak down is good and the bike has blue smoke, it's likely you have leaking valve seals.. What do the plugs look like? A good indicator of a newer motor (say post 1980) is you'll see some oil on the spark plug threads when you remove them.. If the plugs have much color or deposits on the porcelain is another indicator. They should burn almost white..
Club Member
Joined: Mar 2009
Posts: 66,094
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From: Niles Canyon Ca.
Did you happen to listen around the bike while you doing the test ? Air would be blowing out from one of 3 sources, out the carb or the exhaust pipes meaning weak or bad valves or out the breather tubes or oil tank meaning ring blowby.
Feel around the pipes, the black feel wet?
Feel around the pipes, the black feel wet?
Grand HDF Member
Joined: Jan 2012
Posts: 4,445
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From: Oklahoma
How much does the oil go down between changes? Enough oil smoke to be seen is usually blue, too rich is black. Why not ride in the back of the group and stop worrying about it? Do the complainers say if it smells like oil or exhaust (too rich)? They would be the first to go to to get an idea where to start looking. How long since new plugs and/or air filter? Getting any oil out the air filter (crank case a bit too full).
Last edited by btsom; Mar 1, 2018 at 09:23 PM.
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Thread Starter
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Intermediate
Joined: May 2017
Posts: 41
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From: Reno, NV
The plugs seem dark to me. I changed them new last sumer. The center diode seems not cream and sugar but not black, leather brown maybe. The air filter is k&n and it gets cleaned and resprayed with oil. (Not alot)
when I did the leak down test I was listening. Front cylinder was tight a any man would like it lol. The back I could hear just a Lil from the crank case breather hole. Back read 3%loss the front I couldn't even notice the needle drop.
as far as the color I'm not sure. And I don't mind riding in the back of the group but like a lot of us we like put bikes 100. At least I do.
I'm asking some friends if they can recall what color smoke. Like I said I can't see it in my mirror and when I rip on the gas I don't really see it. When I come to a red light I can smell the smoke to though at times.
when I did the leak down test I was listening. Front cylinder was tight a any man would like it lol. The back I could hear just a Lil from the crank case breather hole. Back read 3%loss the front I couldn't even notice the needle drop.
as far as the color I'm not sure. And I don't mind riding in the back of the group but like a lot of us we like put bikes 100. At least I do.
I'm asking some friends if they can recall what color smoke. Like I said I can't see it in my mirror and when I rip on the gas I don't really see it. When I come to a red light I can smell the smoke to though at times.
Last edited by Mhoffer; Mar 1, 2018 at 10:02 PM.
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