Interesting Backfire fix - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 4 (permalink) Old 03-24-2011, 10:27 AM Thread Starter
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Interesting Backfire fix

My bike had some backfiring going on and I figured I'd try stuffing some marbles in the emission hoses when I had the time. First I had a cooling issue to solve though.

While I was checking for leaks and tightening hose clamps I discovered the carb cable linkage on the right side of the bike was completely loose. Talking about the top one (there are two). The adjuster nut was just riding along on the cable. It was a bit of a squeeze getting that nut back on the shaft and tightened back up.

Went for test ride; Backfire Gone

One more problem solved.

Bonus: The previous owner left a 10mm craftsmans wrench in the battery area! At first I thought I might have left it there, but now I have two.
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post #2 of 4 (permalink) Old 03-24-2011, 01:37 PM
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So you are saying that you cured the backfire before you had a chance to marble the reed valve hoses?
Just adjusted and tightened the throttle linkage. Cool. I wonder why that worked?


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Purchased May 16, 2008
Approx.19,300km (12,000 miles)

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post #3 of 4 (permalink) Old 03-25-2011, 12:15 AM Thread Starter
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OlHoss here's my uneducated theory:

Back fire happened whenever letting off the throttle. I think the lower cable is for choke, so the loose one was the main throttle for that carb. Whenever I let off the thottle one cylinder would idle down the way it ought to and the other ( due the slackness of the cable ) would close differently in a way that caused it alter the air/fuel mix vs. rpm to such a degree that it made the condtions right for backfiring to occur.

Just my guess!!

I don't know nuthin' bout no stinkin' carbs.
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post #4 of 4 (permalink) Old 03-31-2011, 02:54 AM
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The two cables on the right side of the carbs are for the throttle opening and closing. 1 is for acceleration, the other is to return it to idle if the throttle cable was to become stuck and hang the throttle wide open.
The choke cable is on the left side of the engine attached to the upper part of the carb.
If one carb is closing sooner than the other one it can cause a backfire, but if that is the case, they need to be synchronized cause are supposed to close together.
The slack in the cable IMO would not open the throttle all the way, but I could be mistaken.
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