leakdown
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Stage IV
Joined: Sep 2012
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From: phoenix
leakdown
Engine making crazy noises and not wanting to run, front cylinder seems to be the problem area. Performed a leak down test, made sure it was on TDCC, held the brake with my foot while hooking up the leakdown tester, getting 80-90% leak down on BOTH cylinders...and I don't mean a loss of 10-20, I mean a loss of 80-90...the only way I could see this even being possible is if a valve was open but I even took the rockers out of the front to ensure that wasn't the case, plus I can hear the air leaking into the bottom end and feel it coming out of the breather hole in the top end and out of the lifter bores on the cylinder I started taking apart. I know I should be doing this to a warm engine but, the engine won't run for more than a few seconds before dieing and making knocking sounds, so I cant get it warm enough to do this properly so I expected extra leakage, but 80-90%!?!?!? I have to be doing something wrong here or is it really possible to have that much wear.
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Joined: Aug 2007
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sounds like the rings or cyl's way out of spec. you didn't say what kind of engine or mileage. To do the leak down right you should pull the air cleaner, oil filler cap and primary cover off and have some one hold a wench on the compensater bolt. Make sure you are on the top of the compression stroke. If the air leaks out of air cleaner the intake valve is leaking ,same thing if air coming out of pipes exhaust valve is leaking. Is it gear drive cams or chains ? did you just change something ? not enough info here to know
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Stage IV
Joined: Sep 2012
Posts: 4
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From: phoenix
Its an 02 softtail, previous owner had a 103 kit installed I believe about 10-15k ago, and I know the basics of a leakdown test, I have done several before but I stopped messing with bikes about 2 years ago and am starting up again and feared I forgot something essential, I have never seen the rings/cylinder get so worn though that they have that much leakdown, I could understand if a piston had a chip or crack in it but both cylinders are giving me crazy high leakdown and it appears to all be through the bottom end.
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Joined: Aug 2007
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A 02 would have had a 88" , so did he stroke the engine or bore and stroke to get to the 103'".My point being did he pull the bottom end ? or are we dealing with just the top end being changed.(if so you might have a 95" motor) 10-15,000 miles is not a lot of miles to explain that much leakage. I would go back and do the test again and with the wench move the piston up and down to hear the air leak from both the intake and exhaust and you should be able to feel the pressure in your hands as it goes to TDC. Hope this helps.
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