Newbie with an engine knock. - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 4 (permalink) Old 09-25-2011, 02:46 AM Thread Starter
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Unhappy Newbie with an engine knock.

Greetings all. Recently purchased an 02 Vulcan 750 with an engine knock. It really didn't sound like a rod knock so I took a chance. As best as I can tell, using a stethoscope, the sound is coming from the upper portion of the front cylinder. The bike has a little over 4,600 miles and the compression is good. Drained the oil and checked the filter and I did not see any signs of metal. I have read about the problems with the Acct's and have replaced them with the manual type with no improvement or difference. Per the Kawasaki service manual, the I.C.Ignitor can cause an engine knock. (although I don't know how) I have checked the readings on the ignitor and the 4 terminal connector reads within range. Only 5 of the 30 readings on the 6 terminal connector read within range. The engine starts and idles O.K. so do I assume that the ignitor is O.K? Could there be a problem in the valve train? Anyone with any suggestions or ideas, please let me know. It looks like you can't do to much with these engines without removing them.

Thought I would add a final chapter to this post. Finally removed engine, front cyl. head, and cyl. exposing front piston. Loose as a goose. Obviously had spun bearing in connecting rod. Now in process of rebuilding.

Last edited by dodger; 11-11-2011 at 12:50 PM. Reason: Found what was causing knock.
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post #2 of 4 (permalink) Old 09-25-2011, 08:23 PM
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Sounds like a stuck HLA Hydraulic Valve Adjuster.
It keeps tension between the camshaft and rocker arms. If one is bleeding off, not keeping pressure, it will make a lot of noise.
Do a search on the forum, and download the bike manual. It's a PDF file, and rather large.
If you don't have a PDF reader, there are several free ones on the 'net. Adobe seems to be the better of the bunch. Go to, and download it.
Best of luck with her, and welcome to the Vulcan madness.
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post #3 of 4 (permalink) Old 09-25-2011, 09:28 PM
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Service manual link:

Roach has a whole series of videos for a complete teardown and rebuild of the vn700/750 engine. See the sticky thread at the top of the Engine tech forum index.

Here is direct link to part 15 where he installing the HLAs, rocker arms etc.


1991 VN 750 -"Cosmic Lady" or "Bad Girl"?
Purchased May 16, 2008
Approx.19,300km (12,000 miles)

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July 13, 2016, Riding on the DARKSIDE now, Classic Radial 165/80-15

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post #4 of 4 (permalink) Old 09-25-2011, 09:45 PM
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Check a little lower on the front and make sure it's not coming from dampers on the balancer (in the bottom end). They make a deep "thump" sound when they start to go. Easy fix, though, so there's some good news!

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