Leak down test
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Cruiser
Joined: Nov 2008
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From: Beaver, OK. (No mans land)
Leak down test
I have a 1994 Electra Glide stock 80 Evo. I was doing prewinter checks on it and thought i would do a leak down test and heres the scenario, checked the front cylinder and checks great I move to the back cylinder and can hear air escaping through intake valve when I put my finger over the timing plug hole, I'm thinking maybe I'm not on compression stroke so I put my finger in the spark plug hole bump it over untill comes up on compression turn it over by hand with screwdriver in sparkplug hole untill I get piston at top and still get the same results, I tryed this three more times to make sure with same results each time. So I pull the head on that cylinder and remove the intake valve and it looks good, I can see a nice shiney seal all the way around the valve and seat So now I'm lost as to where this air was escaping. I did adjust the pushrods all the way off to make sure this was not the culprit. Any sugestions please?
Road Master
Joined: Apr 2009
Posts: 1,123
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From: NJ
Did you do a compression test along with the leak down, results?
Did you have any symptoms that caused you to do the leakdown in the first place?
How many miles on the engine and any prior issues?
I did a leak down on mine this year and the rear cylinder hissed out the intake a little the first go-round but the guage showed only 10%. I cycled the engine a couple of times and rechecked it and it was great. Could be I didn't have it exactly TDC the first time or it moved a little when I hit it with air. I've found you need to be sitting on the bike with the brake applied when you turn the air on or it will try to move. Also, don't use a screwdriver in the hole, something plastic like a straw or wire tie is better in case it gets wedged while your spinning the engine..Plastic won't hurt anything.
Not sure I would have taken the head off just yet but since you have, might as well get the valves & seats cleaned up and whatever else you have in mind with consideration to the mileage on the engine. If I ever take mine off I'll do it all one shot and get it over with, both jugs.
Doug
Did you have any symptoms that caused you to do the leakdown in the first place?
How many miles on the engine and any prior issues?
I did a leak down on mine this year and the rear cylinder hissed out the intake a little the first go-round but the guage showed only 10%. I cycled the engine a couple of times and rechecked it and it was great. Could be I didn't have it exactly TDC the first time or it moved a little when I hit it with air. I've found you need to be sitting on the bike with the brake applied when you turn the air on or it will try to move. Also, don't use a screwdriver in the hole, something plastic like a straw or wire tie is better in case it gets wedged while your spinning the engine..Plastic won't hurt anything.
Not sure I would have taken the head off just yet but since you have, might as well get the valves & seats cleaned up and whatever else you have in mind with consideration to the mileage on the engine. If I ever take mine off I'll do it all one shot and get it over with, both jugs.
Doug
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Joined: Sep 2009
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From: deland,florida
when we leak down a motor,we remove the p/rods and crank the motor to tdc with the nut on the compensator.we use 100# of air and on a street motor with miles on it,you will always get a little coming by the valves,but shouldnt be any more than 5-10%,10%`s telling you its about time to cut valve & seats,or rings if airs coming out the timing hole.and should be equil in both cylinders.if your striving for 0 leak down,use total seal rings
kirby
vee twin racing
kirby
vee twin racing
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Cruiser
Joined: Nov 2008
Posts: 139
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From: Beaver, OK. (No mans land)
Found it had a bad seat acording to the machine shop so pulling other head and jugs and do a topend rebuild 43564 mi. Allready done the cam and lifter change with new cam bearings so I get this done I should be in good shape for awhile. Thanks let you know how it goes.
Thanks Todd
Thanks Todd
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