Running Rough around 2.5-4k RPMS - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
Carbs and Fuel System
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post #1 of 5 (permalink) Old 11-09-2009, 04:56 PM Thread Starter
ryn
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Running Rough around 2.5-4k RPMS

Okay, I Just removed and cleaned the carbs a month ago. Then the petcock started acting up, so after getting the diaphragm replaced I put some gas in and headed to the gas station, I ran out of gas and had to switch to reserve. Filled her up and took her back home. Everything seemed great.

The next day I went for a ride with a friend. In the 10 mile ride meet up I was cruising at around 50mph 4.5krpms and I had plenty of power, no sluggishness, If I goosed it she would move. Then I hit the city and had to stop and go. I noticed (mainly while turning from a stop) that the bike looses power and hesitates above idle to 3-3.5k. I'm also only getting about 100miles till I need reserve. What do you guys think would be the most likely problem? At all other RPM's the bike seems fine. There doesn't happen to be a lowspeed needle adjustment that I'm missing?

And also on occasion at a stop the RPM's would stay around 3k for a few seconds. When it was acting up I tried spraying some wd40 around all boots and what not and no apparent air leaks.
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post #2 of 5 (permalink) Old 11-09-2009, 05:17 PM
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Quote:
Originally Posted by ryn View Post
Okay, I Just removed and cleaned the carbs a month ago. Then the petcock started acting up, so after getting the diaphragm replaced I put some gas in and headed to the gas station, I ran out of gas and had to switch to reserve. Filled her up and took her back home. Everything seemed great.

The next day I went for a ride with a friend. In the 10 mile ride meet up I was cruising at around 50mph 4.5krpms and I had plenty of power, no sluggishness, If I goosed it she would move. Then I hit the city and had to stop and go. I noticed (mainly while turning from a stop) that the bike looses power and hesitates above idle to 3-3.5k. I'm also only getting about 100miles till I need reserve. What do you guys think would be the most likely problem? At all other RPM's the bike seems fine. There doesn't happen to be a lowspeed needle adjustment that I'm missing?

And also on occasion at a stop the RPM's would stay around 3k for a few seconds. When it was acting up I tried spraying some wd40 around all boots and what not and no apparent air leaks.
there is an air mix screw next to the vac port on the carbs behind a lead circle plug...

Try seafoam im guessin though u just rebuilt im thinking the bottom of the tank has some bad gas/ moisture in it try running the fuel out of the tank and start from scratch also poor ome sefoam in the carb bowls and let them sit ...

is it rpm or throttle position problem ... carbs tend to be throttle position where elec tend to be more specific to RPM's ...



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post #3 of 5 (permalink) Old 11-09-2009, 06:08 PM Thread Starter
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Well I guess it could be throttle position. I will keep an eye on exactly when it acts up. I'll run some seafoam this next tank as I feel like it does run better on a full tank, maybe debris is causing the issues.
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post #4 of 5 (permalink) Old 11-10-2009, 09:16 AM
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I agree with SeeBee, drain your gas and maybe even flush your tank with a little fresh gas then fill it with clean gas and some seafoam.

You said it wouldn't return to idle a few times and it is possible that your throttle cables are sticking. Make sure they are free and your throttle snaps back to the stop cleanly and smoothly. If that is all fine, then I would be looking for a vacuum leak of some sort. If the throttle cables are fine, then this almost ALWAYS points to a vacuum leak. Especially if it only does it when the bike is warmed up...

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post #5 of 5 (permalink) Old 11-10-2009, 03:23 PM
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A few months ago I had a similar problem where it was sputtering at anything over 1500 RPM and I was getting 1/3 less milage as usual and from what I figure it was a float that was stuck for the rear carb. I was able to free it up and the hesitation and gas guzzling went away.

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