motor knock - Kawasaki Vulcan Forum : Vulcan Forums
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post #1 of 5 (permalink) Old 03-01-2010, 09:07 PM Thread Starter
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motor knock

I went in for my 15,000 mile valve check . The mechanic said he changed it very little. Every since then I have a knock in the motor when I get on it. I talked to the mechanic he told me to put in 91 octain gas it. I had been using 87 octain with out any knock sence I bought it new. I have put in 2 tanks of gas of the 91 octain and I still have the knock. Any ideas why it is still knocking? Thanks
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post #2 of 5 (permalink) Old 03-01-2010, 09:53 PM
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Adjusting the valve clearance should not cause the engine to start knocking/pinging. These bikes are set up to run on 87 octane (US) per the owners manual.

Something else was changed, like possible the timing. May be a case of a wire connection that was disconnected to gain access to the valves/rocker arms and not reconnected causing the ecu to advance the timing, or the timing just being incorrectly set.

This is just a guess as to what may be causing the problem, , but I think the issue is clearly timing related.

I know this isn't a lot of help, but timing would be my focus at least initially.

Check the work order to see what he adjusted besides the valves.


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Last edited by Shiloh; 03-01-2010 at 10:00 PM.
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post #3 of 5 (permalink) Old 03-02-2010, 11:59 AM
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is it a mechanical knock or a spark knock? If it only does it at very low rpm like the 800's do then it is the counterbalance rubbers. Same thing the 800 does. I have no idea what the 900 had for a warranty period but it will be a warranty item if still under a valid warranty.
Spark knock will come and go depending on quality and octane rating of gasoline.

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post #4 of 5 (permalink) Old 03-02-2010, 04:18 PM
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Maybe they changed the oil to 20-50? Usually kawa dealers don't do it or recomend but if that's the case then just go back to 10-40. I once upgraded to 20-50 even after the dealer said don't and after 1000 miles I had to go back to 10-40 oil. All the knocking noises and the tranny clunk went away. 10-40 ever since.

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post #5 of 5 (permalink) Old 03-02-2010, 07:02 PM
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I'd take it back and have him check it out, it obviously shouldn't be knocking after any kind of service.

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