Fuel Starvation at High RPMs - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 7 (permalink) Old 02-16-2017, 09:59 AM Thread Starter
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Fuel Starvation at High RPMs

Hello gentlemen,

Issue:

I have a '93 with about 11,000 miles on it. All stock, no mods. Good overall condition.

Having an issue that appears to be related fuel starvation. While riding at highway speeds with a constant RPM of between 4K and 5K, after about 10 minutes the bike will lose power and die. It "feels" like the bike is out of gas, but of course there is a plenty in the tank.

When this happens I pull over and wait maybe 2 minutes then the bike fires right back up. It seems like at those constant RPMs the fuel is being burned quicker than it is being replaced.

Riding around the city the issue never occurs. It is only when riding on highway with constant high RPMs.

What I have done so far (none have had any effect):
1. Rode with gas cap open
2. Removed and examined petcock. Was perfectly clean with no damage.

Anyone have any ideas what could be causing this?
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post #2 of 7 (permalink) Old 02-16-2017, 11:06 AM
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You could try checking the hose that goes into the back of the right air filter. This is the vent for the float bowl. If it's loose or stuck in too far you can have "running out of gas" symptoms. Cut the end of the hose at a 45 degree angle and stick it back into the air filter.
Have you tried using Sea Foam?
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post #3 of 7 (permalink) Old 02-16-2017, 11:15 AM Thread Starter
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I have used SeaFoam. I will look at that hose tonight. I have a feeling you may be right. Thanks!
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post #4 of 7 (permalink) Old 02-17-2017, 09:54 AM Thread Starter
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Indeed the tube leading from the carbs to the right air box was missing. The tubes went from the carbs to the T fitting, then no where. I decided to go ahead and do the ear shave procedure as I am sick of not being able to get at the carbs. Will be working on cutting out the surge tank tonight (Yikes that's a real pain!)

Quick question, after the ear shave where will the carb vent tube go?
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post #5 of 7 (permalink) Old 02-17-2017, 09:57 AM Thread Starter
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Indeed the carb vent tube was missing. The tube went from each carb, to the T fitting, then nowhere. The tube that should go from the T fitting to the right airbox was missing. I decided to go ahead and do the ear shave procedure because I'm sick of not being able to access the carbs. I'll be cutting out the surge tank tonight. Yikes that's a real pain!

Quick question, where will the carb vent tube go once the ears are shaved?

Thanks for all your help. Much appreciated!
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post #6 of 7 (permalink) Old 02-17-2017, 10:53 AM
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You'll have to route it up somewhere that has no moving air. Most here tape it up under the gas tank on the front of the frame.

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post #7 of 7 (permalink) Old 02-20-2017, 09:55 AM Thread Starter
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Ear shave procedure fixed the problem. Once that was done I was able to properly route the carb vent tube and the issue was resolved. Thanks for all your help!
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