carb problems? popping and cracking on when off throttle. - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 6 (permalink) Old 10-17-2011, 11:41 AM Thread Starter
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carb problems? popping and cracking on when off throttle.

Ok I need some help or at least reassurance that what I'm having is normal. I have a 1994 750 with 06 carbs. The carbs are still all factory settings as far as air screw and syncing. I have rejetted to 142/42's .I have the ears shaved with cone filters on each Carb. I am also running jardine pipes(open). I have taken the covers off the side of the heads and replaced with some coasters. And still I get the popping and cracking while of the throttle when riding. Any and all help is appreciated.
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post #2 of 6 (permalink) Old 10-17-2011, 12:00 PM
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adjust the air/fuel screws... screw all =the way in.. and about 2 1/2 turns out
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post #3 of 6 (permalink) Old 10-17-2011, 02:57 PM
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Check your coasting enricheners, you shouldn't have any popping when coastered, unless you have a lean condition caused somewhere in the carb, or an air leak somewhere. Afterfiring causes higher exhaust temperature, so your headers will turn blue.
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post #4 of 6 (permalink) Old 10-19-2011, 03:23 PM
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could be that a diaphragm is broken and or cracked and needs to be replaced
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post #5 of 6 (permalink) Old 10-21-2011, 11:30 PM
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Unfortunately, once you deviated from factory jetting and filters, finding a solution will be trial and error. I would definitely remove the plugs and turn the pilot screws out 2 1/2-3 turns, and remove every single part of the air injection system. since you no longer have an airbox, you won't have to plug the hole in that, but you will need to cap the unused vacuum fitting on the rear carb. You will need to cap the reed valve covers on both heads, you can get coasters for this purpose, or you can do what I did, and use the original covers, with rubber caps on them. The caps I used were from Autozone, and were designed to plug heater hose fittings on cars. They fit the bike perfectly, and cost $1.99 for 2.

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1997 Vulcan 750, purchased about a week ago
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2001 Yamaha XT225, heavily modified
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post #6 of 6 (permalink) Old 10-22-2011, 09:14 PM
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Just another thought ..... when you changed exhaust were new crush gaskets used? Leaks there will have the same effect.

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