no power/misfires under 3000rpm - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 4 (permalink) Old 08-31-2008, 08:56 AM Thread Starter
 
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Question no power/misfires under 3000rpm

I recently had a lot of problems with my -86.
It wouldn't idle and so on(see the engine section for the full story).
Now after a rebuild of the carbs, the bike idles great and acceleration is also great.. The problem is that the bike misfires and runs uneven under 3000rpm's, it almost feels like running out of gas. If I give it some gas it accelerates just fine but it's no fun when you ride in town at 30mph on high gears and the bike jump you all around.
When I tested to turn the pilotscrews while the bike was running, the rear carb behaved as expected. If I turned it all the way in the bike stopped and the bike reacted, the front carb screw however didn't react at all.
Does that suggest a leak somewhere?

Last edited by swevulcan; 08-31-2008 at 09:32 AM.
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post #2 of 4 (permalink) Old 08-31-2008, 10:45 AM
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If turning the screw had no effect that is probably a pilot jet issue. It's the smallest one and a PITA to get 100% clean. You gotta pull the carbs again. After yu get the float bowl off, drip some berrymans into the bottom of the pilot jet hole. Let it sit. If it's clogged, the hole will fill up. Do that 3 times. Then use compressed air and a soft tip and blow the hole out by pressing the tip against it. You should have a good seal on your side so the air is forced out the other side throgh the 4 tiny holes. You can check by putting your finger in the throat of th carb while doing it if the air is coming through OK. Onceyou have equal air on both sides you're good to go.

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post #3 of 4 (permalink) Old 08-31-2008, 02:57 PM
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I agree with AJ. I know the carbs are a pain to get out but your problem sounds like a clogged jet. I've had mine out 3 times for various issues. One thing further. Make sure you tighten all the jets in place. I had my high speed jet vibrate out of its holder which caused the rear cylinder to cut out above
3K RPM.

Jim W
93 VN 750 "Ursula"
Moved R/R 08Sep06
R/R rewire 17Feb07
New R/R, Installed 14Jun08
New Stator installed 10 Jun08
Maintenance Free Battery 12Jan08
21480 Miles
VROC #8542
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post #4 of 4 (permalink) Old 09-10-2008, 10:36 AM
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maybe it is the carb's and not timing,
Im gonna call the dealer where i got it and ask him about this
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