Carb sync blues

1864 Views 9 Replies 9 Participants Last post by sandiegobrass, Jul 31, 2009

mantra

Discussion Starter · Jul 30, 2009

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Ok folks, I decided to sync my carbs today even though the bike was running fairly well with a little extra throttle in first. Sooooo I got out my vacuum gauges and went to work. Number3 read around 5 hg number 1 around 15 so I lowered the vacuum to match number 3. So far so good. Left side number 4 read 17 hg so I matched number 2 to it. At this point I began to hear a loud knocking on the right bank. HMMMMM what is that? My feeling is that it is the vacuum diaphragm topping out in number 3. At this point the idle just dropped off and the bike stalled out and I have not been able to get back where I started,when the bike ran pretty well and did not make any noise. The only constant that I am aware of at this point is that number 3 has not and cannot change. The knocking is enough to make me not want to ride th bike causeit sounds like crap. Is there any way I can get back to square one and start over?

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Endwell_Tim

· #2 · Jul 30, 2009

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Just want to point out that #3 does indeed change, but only when you change your idle screw. How many gauges are you using?

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DaveO430

· #3 · Jul 30, 2009

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Match #4 to #3 and it should be good to go. Get it started and adjust the main idle screw until it will idle on it's own.

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sandiegobrass

· #4 · Jul 30, 2009

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Sort of same answer as Dave... Up the idle speed (at the screw) and continue... I often intentionally set the idle at 1500 to start so that I don't get into a bind (by one or more carb plates getting too close to closed)

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cntryboy1289

· #5 · Jul 30, 2009

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I had the same problem with mine on Monday, got it idled correctly and got the carbs to sync just fine. I had a bunch of water in mine that helped me get the carbs out of line with each other without the gauges. Take your time and I think you will get the rattling to go away before you know it.

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Wichita Scorpion

· #6 · Jul 30, 2009

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Another thing you might check is to make sure the vacuum guages are reading the same. Test them on one vacuum source and note any differences in guage readings.
Balance #1 to #3, then #2 to #4, then #4 to #3, adjusting idle screw as needed.

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jenrobsdad

· #7 · Jul 30, 2009

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When you had one carb out of sync and heard that awful noise, what did it sound like and where did it seem to come from on the engine? I am hearing a clatter sound toward the rear of my GL1200 while ideling. I am hoping all it may need to have carbs synced.

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squirts

· #8 · Jul 30, 2009

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jenrobsdad wrote:

When you had one carb out of sync and heard that awful noise, what did it sound like and where did it seem to come from on the engine? I am hearing a clatter sound toward the rear of my GL1200 while ideling. I am hoping all it may need to have carbs synced.

Others may disagree, but it sounds to me like a clutch pack rattle. It's been my experience that the clutches can rattle at idle. Carbs out of synch usually sound like a rod knocking... It's a distinctly different sound. Good luck & take care, Squirts