rejetting a VN700 - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
Carbs and Fuel System
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post #1 of 16 (permalink) Old 10-13-2008, 12:24 PM Thread Starter
 
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rejetting a VN700

I was wondering if anyone has rejetted a VN700? My bike runs good, but has no change in acceleration passed half throttle. She also takes forever to warm up. Even in 75 degree weather I will have to choke her for about 5 minutes or she will bog when I take off. I checked my plugs and they are tan. Hot restarts have not really been a problem. I was wondering if rejetting whould help or are these bikes just that slow? This is my first bike and my friend's stock 883 sportster is faster.
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post #2 of 16 (permalink) Old 10-13-2008, 01:54 PM
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I believe you are not getting enough fuel to the carbs. Check the vaccuum hose that goes from the intake to the petcock. It may have a air leak. Best to replace it, a leak is hard to detect on that hose.

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post #3 of 16 (permalink) Old 10-13-2008, 02:55 PM Thread Starter
 
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I'll give it a try. Do you think if I run her on prime that I sould feel a differnece? That way there would be no way to starve the engine. Just for test purposes.
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post #4 of 16 (permalink) Old 10-13-2008, 03:00 PM
 
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maby you can run some seafoam in the tank may be the first place to start (and what niterider recomended), from hanging out here and reading a lot of posts your vn should smoke the 883 (at least in the 1/4 mile). someone correct me if im wrong.

Last edited by dutter; 10-13-2008 at 03:03 PM.
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post #5 of 16 (permalink) Old 10-13-2008, 03:27 PM
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It sounds to me like you are only running on one cylinder. You may have a clogged high speed jet or the jet may have vibrated loose and is laying in the carb bowl. I'd try the Seafoam first but it may be that a carb pull is in order.

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
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post #6 of 16 (permalink) Old 10-13-2008, 03:43 PM Thread Starter
 
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The carbs have been completely rebuilt and the bike runs pretty smooth. The guy who went through them cleaned and soaked them for about a week. I have used a Locus carb and injector cleaner on the bike at least twice this year with no change.
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post #7 of 16 (permalink) Old 10-13-2008, 03:47 PM
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Any mods on this bike, pipes, air filters???

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post #8 of 16 (permalink) Old 10-13-2008, 03:52 PM
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Just because they have been rebuilt doesn't mean there can't still be a problem. You should smoke the 883 without even breathing hard. The reason I feel that you are only running on one cylinder is your comment about no change in acceleration after half throttle and the bike taking forever to warm up. The bike will sound smooth with only one jug firing but will be very sluggish on acceleration and won't go much above 60 mph without going downhill or in a stiff tail wind. I know whereof I speak because I had the high speed jet fall out of its mount in the carb causing the rear cylinder to cut out at anything over 3k RPM. The engine idled smoothly and accelerated nicely until that 3K limit and then would be very sluggish and not accelerate after half throttle. There was no backfiring or even the sound of a misfire, it just got sluggish. I knew something was wrong because this isn't normal. This happened about 2 months AFTER a carb cleaning and rebuild. Also, if the jet was clogged in the first place and was never unclogged, if you haven't felt the way the bike's supposed to run, you wouldn't know the difference. These bikes are really quite fast for a cruiser and can blow the doors off most other cruisers out there. If yours is not doing this, I suspect you are only running on one cylinder.

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
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post #9 of 16 (permalink) Old 10-13-2008, 03:55 PM
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Quote:
Originally Posted by Sky Rider View Post
Just because they have been rebuilt doesn't mean there can't still be a problem. You should smoke the 883 without even breathing hard. The reason I feel that you are only running on one cylinder is your comment about no change in acceleration after half throttle and the bike taking forever to warm up. The bike will sound smooth with only one jug firing but will be very sluggish on acceleration and won't go much above 60 mph without going downhill or in a stiff tail wind. I know whereof I speak because I had the high speed jet fall out of its mount in the carb causing the rear cylinder to cut out at anything over 3k RPM. The engine idled smoothly and accelerated nicely until that 3K limit and then would be very sluggish and not accelerate after half throttle. There was no backfiring or even the sound of a misfire, it just got sluggish. I knew something was wrong because this isn't normal. This happened about 2 months AFTER a carb cleaning and rebuild. Also, if the jet was clogged in the first place and was never unclogged, if you haven't felt the way the bike's supposed to run, you wouldn't know the difference. These bikes are really quite fast for a cruiser and can blow the doors off most other cruisers out there. If yours is not doing this, I suspect you are only running on one cylinder.
I took mine to the track just to see what it would do. I had a speed of 75 mph and 9.5 sec in 1/8 mile.

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post #10 of 16 (permalink) Old 10-13-2008, 04:00 PM
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The 883 isn't even in the same ball park.

A fully clogged or missing jet will give the non fire on a cylinder. It's the partially clogged jets that get the misfire/backfire symptoms. I've had both sets of symptoms. The partial clog can sometimes be cured with Seafoam. The fully clogged or missing jet will need a carb pull and disassembly.

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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