Performance Woe, no top end - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 7 (permalink) Old 09-09-2011, 09:14 AM Thread Starter
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Performance Woe, no top end

Recently purchased 2001 vn 750. Engine purrs but won't roar. 5th gear, around 4,200 rpm, 70mph,,, that's it. Nothing indicates an engine problem other than lack of top end. Feels as if a governor was put on this machine, otherwise runs great.

Appreciate if anyone can provide a scenario of things to troubleshoot before I take it into a shop.
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post #2 of 7 (permalink) Old 09-09-2011, 09:23 AM
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Check the hose that fits into the back of the right airbox...pull it out, cut the end at a 45 degree angle and stick it back in.

Can you rev the bike up towards redline in neutral ?

Make sure the throttle is opening all the way, and there are no airleaks around the carbs.

You are using regular gas right?

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post #3 of 7 (permalink) Old 09-09-2011, 09:25 AM
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Have you tried half a can of Sea Foam in a tank of fresh gas? I'm guessing a carb issue, but someone else may have another idea. IIRC, mine hits 70 mph around 5,000 rpm. And yes, it should have plenty left after that.

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post #4 of 7 (permalink) Old 09-09-2011, 09:33 AM
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My VN 750 has been earshaved and not jetted so only does about 70 to 80 top speed, getting new jets this tuesday so will be fixed and back to top speed.
I also had a power problem were on inspection i had a torn carb diaphragm now this is fixed i can pull off fast but until the jets are in my carbs i still cant get to full speed.
Sounds like you could have a carb problem, im not too good with mechanics but hopefully my little carb problems can give you a little insight to what it could possibly be.
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post #5 of 7 (permalink) Old 09-09-2011, 10:10 AM
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How about an exhaust restriction.

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post #6 of 7 (permalink) Old 09-09-2011, 01:27 PM Thread Starter
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Follow Up

Quote:
Originally Posted by Knifemaker View Post
Check the hose that fits into the back of the right airbox...pull it out, cut the end at a 45 degree angle and stick it back in.

Can you rev the bike up towards redline in neutral ?

Make sure the throttle is opening all the way, and there are no airleaks around the carbs.

You are using regular gas right?
No redline in neutral: 8grand, throttle does open all the way, will investigate airbox hose and carb leaks. Thanks for response.
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post #7 of 7 (permalink) Old 09-09-2011, 04:29 PM
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Just my 2c...

Sounds like fuel starvation to me.....
...check for good fuel flow as well...its both gravity and vaccuum, so check filter at petcock, the hoses like Knife stated, and the cap vent.



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