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Hard Kick on fresh top end

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birdieman720

Hard Kick on fresh top end

#1

Post by birdieman720 » Sun Sep 14, 2008 8:01 pm

Guys,

My 185 pounds is having trouble kicking the freshly rebuilt top end of my '54 Pan.
New cylinders, valves etc...
Had to take quite a bit off (close to max.) the heads to get them flat.
Has anyone else encountered this problem?
Will this problem go away with break in, or do I need a 300 pound buddy following me on every ride?
Bike runs great otherwise.

Thanks.........



Panacea
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Re: Hard Kick on fresh top end

#2

Post by Panacea » Sun Sep 14, 2008 11:41 pm

How much is "quite a bit?" I shaved .008 off my 49 heads to get them flat and couldn't notice a difference in kick starting, Can you do a compression test?

birdieman720

Re: Hard Kick on fresh top end

#3

Post by birdieman720 » Mon Sep 15, 2008 12:59 pm

Thanks Panacea.

Not sure how much they removed, but the head was teetering in the cylinder fire ring.
The gasket made up the difference (no compression leaks).
Will the test give a clue if there is too much compression?

Cotten
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Location: Central Illinois

Re: Hard Kick on fresh top end

#4

Post by Cotten » Mon Sep 15, 2008 1:30 pm

birdieman720!

If the cylinder will not mate to the head, you will not have to worry about "too much compression" for long.
Even if the gasket manages to survive, the fastener stress will be transfered to the cylinder at the spigot, causing a bulge in the bore wall right where the rings encounter the most force.
The spigots or "fire rings" should be reduced.

Back to starting effort:
Please tell us what cam is installed, and how you have adjusted the valve train.

...Cotten

birdieman720

Re: Hard Kick on fresh top end

#5

Post by birdieman720 » Mon Sep 15, 2008 7:08 pm

Correction, the fire rings were taken down to suit the "short" heads.
Stock cam.
Solid push rods, adjusted to spin with slight drag.

Pomike
Posts: 243
Joined: Thu Jul 03, 2008 5:54 pm

Re: Hard Kick on fresh top end

#6

Post by Pomike » Wed Sep 17, 2008 12:54 am

Does it get easier when you pull in the clutch?
Mike

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Re: Hard Kick on fresh top end

#7

Post by awander » Wed Sep 17, 2008 1:20 pm

It should get REAL easy... :shock:

FlatHeadSix
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Re: Hard Kick on fresh top end

#8

Post by FlatHeadSix » Wed Sep 17, 2008 2:34 pm

The clutch could very well be the problem. If the clutch is slipping just enough so that it drags instead of kicking the engine all the way through it will "feel" like very hard kicking. And, of course, the engine won't start very well either until you're lucky enough to get it to kick all the way through a compression stroke. Adjust the clutch and try it again.

The other likely cause has already been mentioned, valve adjustment. If the valves are not lifting enough to release the compressed mixture in the cylinder it just continues to build up and feels like you have 20:1 compression ratio. This is common with faulty hydraulic lifter systems, if you're running solids and have them adjusted correctly it is less likely.

What pistons did you use for the top end rebuild?, Stock 8.5:1, or higher?

mike

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