Hesitation at high speed - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 14 (permalink) Old 12-07-2013, 02:06 PM Thread Starter
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Hesitation at high speed

Hello gents,

2000 vn750 with 24,000 on it. I am experiencing hesitation at around 45-50mph. What I mean by hesitation is that it feels like the bike is missing or possibly not getting enough fuel, Im not too sure. I rebuilt the carbs last year but didn't replace the floats and one of the plungers on the floats was worn out. Im also having an issue where after I fill it with gas it's hard to start then eventually backfires and shortly after starts up (I am usually giving it throttle while trying to start). Any ideas? I have a new battery that holds charge and decent plugs that don't look fouled out. I do however want to put new wires on the beast.

2000 VN750(A16)
*Richmond, Va*

25,000 Miles
Jetted, Shaved, Coastered
New Petcock
New Fuel & Vacuum Lines
New Plugs
Spline Lube
ACCT to MCCT
New Oil in Final Drive
Acid & Naval Jelly'd Gas tank
Luggage Rack
Hard Saddle Bags
Extended b*%ch Seat

(time for a new rear tire and state inspection)
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post #2 of 14 (permalink) Old 12-07-2013, 03:17 PM
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the hard starting and the backfire is probally battery related.get an agm battery if ya don't have one.get some iridium spark plugs.has the bike sat for any length of time with ethanol gas in it?could have a plugged jet,or could the plunger you were talking about.

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post #3 of 14 (permalink) Old 12-07-2013, 03:18 PM
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Carb vent hose routing

Search the forum for Carb vent hose routing. There is a T where two hoses come out of the carb. One has to be in dead air or it will cause stumbling. This sounds two simple but it makes a big difference. I know been there. There have been several threads on this.

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post #4 of 14 (permalink) Old 12-07-2013, 06:41 PM
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Quote:
it's hard to start then eventually backfires and shortly after starts up (I am usually giving it throttle while trying to start). Any ideas?
Try starting it with no throttle, mine does the same thing if I open the throttle, but starts in half a turn with the throttle closed.

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post #5 of 14 (permalink) Old 12-07-2013, 08:14 PM
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Got to agree with Mcnueby with the carb vent line that tucks behind the right ear on this one. My other thought would be a minor vacume leak. These bikes CV carbs tend to stumble and not pull well at higher rpms/speed if there is a vacume leak.

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post #6 of 14 (permalink) Old 12-10-2013, 01:54 PM Thread Starter
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I appreciate the insight gentleman. The bike has been jetted and shaved and the vent line cannot connect behind the right ear... I have moved that line, as well as cut a 45 degree angle but am unsure if having the line sit near the battery is still creating a vacuum since it's accessible to air. I have a battery thats only 7 months old and it's potential that a jet is clogged however I rejetted last year and the gas tank is rust free with new petcock. I'll try changing out the wire's as well as change out that plunger that's worn. Thanks again for the insight!

2000 VN750(A16)
*Richmond, Va*

25,000 Miles
Jetted, Shaved, Coastered
New Petcock
New Fuel & Vacuum Lines
New Plugs
Spline Lube
ACCT to MCCT
New Oil in Final Drive
Acid & Naval Jelly'd Gas tank
Luggage Rack
Hard Saddle Bags
Extended b*%ch Seat

(time for a new rear tire and state inspection)
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post #7 of 14 (permalink) Old 12-10-2013, 05:56 PM
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Vent Hose

You say the vent hose is hanging by the battery, I think there may still be a problem with the hose. When I got my bike the hose was hanging down there some place. I still have my ears so I put it where it is supposed to be and it runs well now. I'm not sure how you should route it but check with other guys that have shaved there bikes. I know it seems like that should not be a problem but from my experience I know it is important. The signs are it will run well up to about 45 mph then it acts like it is not getting gas or something.

Good Luck

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post #8 of 14 (permalink) Old 12-10-2013, 05:59 PM
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I think many with shaved ears route that hose up to the area under the tank where the air box was. should be pretty calm air there
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post #9 of 14 (permalink) Old 12-11-2013, 05:27 AM
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I had an occasional stumble/hesitation after I ear shaved. I ended up routing the vent hose up under the gas tank and behind the radiator. I zip-tied it up to the frame under there. After that I haven't had anymore issues.

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post #10 of 14 (permalink) Old 12-11-2013, 11:08 AM
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Mine is doing the same thing Audible... same year, and about the same mileage... I'll have to check the vent hose too...

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