Author Topic: Compression concerns  (Read 913 times)

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flyboy

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on: September 08, 2013, 01:56:25 pm
Hello All. This is my first summer with my '99 Bullet 500 (7,500 mi) and loving it. Although I have a mechanical background, I'm still getting familiar with the Bullet.

I've read that the compression should be so great, one can actually "stand" on the kickstarter. Mine does not come close to this. Obviously, I feel increased resistance at top of compression stroke, but I can "push" thru it with steady force. I still use the decompression as part of my starting drill. My compression tester does not have a threaded end, it's the kind with the rubber push-on nipple so I can't get a good reading....I'm working alone.

My confusion is the fact that it's running great. It starts easily, has good pulling power thru all gears at various throttle settings and has excellent tick-over. Very smooth and steady. None of which I'd expect with "low" compression.

Yesterday, I pulled the decompression valve to check....all in good working order. I lapped the valve seat while there too. Put back together and pretty much the same compression. 50 mile ride out proved flawless last night.

Is the "standing on the kickstarter" an overstatement? Should I be concerned, or just keep riding? Perhaps a bugger of carbon on the exhaust valve seat? Anything else I can try to help discover the issue....before a top-end job? Am I creating deeper problems by riding it, with this "perceived" low compression...when she's running so good?

Thanks in advance!


ace.cafe

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Reply #1 on: September 08, 2013, 02:16:20 pm
A stock Bullet won't hold up a person on the kick starter.
It is a very low compression engine. It has a 6.5:1 compression piston in it.
I could always kick right thru the compression stroke with my 2000 stock Bullet.


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High On Octane

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Reply #2 on: September 08, 2013, 02:50:54 pm
Maybe if you weighed 60 pounds you could stand on the kicker without it moving.  Like Ace just said, these are pretty low compression motors and are pretty easy to kick thru.  I have a vintage twin with 7 1/4.1 compression and there's no way I could stand on my kicker either.  Now there ARE some big displacement V-Twin Harleys out there that you CAN stand on the kicker, and they are not fun to start.  I was on a Poker Run yesterday and there was a guy with one.  Guess what?!  He had to have a friend push him on the bike to pop start it as we left every stop.  My bike started on the 1st or 2nd kick every stop.   ;D

Scottie
2001 Harley Davidson Road King


flyboy

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Reply #3 on: September 08, 2013, 02:56:17 pm
Thanks Ace and Scotty! That's what I wanted to hear!! I couldn't understand why it would start, and run so well, if I had a low compression issue. I guess I've been reading posts from high performance engines? I'm just gonna ride-on.
Thanks for the quick reply!