Throttle problem - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 7 (permalink) Old 12-06-2011, 09:10 PM Thread Starter
2002 VN 750
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Question Throttle problem

I have what I think is a newbie question. When my fuel gauge drops to 1/4 full my 02 VN 750 runs out of gas and dies, it has happened twice so far. So I make sure it stays above half all the time.
I have had some starting issues too but I replced the battery the other day.
Now when I was riding to work today about 14 miles one way at the 10 mile mark cruising in 5th gear at 55mph my bike started to lose power?
So I throttled it up about 1000rpms and it got some power back, but then lost power again.
At stop signs I needed to stay on the throttle, when I hit about 3000rpms it took off good?

I'm a new motorcycle owner so any help would be great.

Thank you ahead of time.....
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post #2 of 7 (permalink) Old 12-06-2011, 09:20 PM
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Welcome to the boards.

Check out the post on Phantom Out of Gas Syndrome here and see if it is of any help as that sounds like what you're going through.

If not, maybe something is a bit clogged; you could run some SeaFoam additive in your next tank and see how she runs after.

Edit: I see you have or had starting issues. You could also check your plugs and make sure they're not fouled or old. If so, then it would be a good time to switch to Iridium plugs as they really seem to help our bikes out.

1986 Kawasaki Vulcan 750
NGK Iridium Plugs #7803/DPR7EIX-9
Duralast Gold ETX15 AGM Battery
Coastered & Shaved
Metzeler ME880 [110/90-19, 170/80-15]
Balance Dampers Replaced
Tuxedo Mod
Rebuilt Forks w/ Progressive Springs
V&H Cruzers Grill Cover
Meanstreak Seat
Emgo 23-92411 Handlebars

1990 Kawasaki Vulcan 750

1998 Honda VFR800 FI

2014 Honda VFR800F

1989 Pontiac Firebird Formula 350

Last edited by thtanner; 12-06-2011 at 09:22 PM.
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post #3 of 7 (permalink) Old 12-06-2011, 09:36 PM Thread Starter
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Thank you thtanner
I will try those options and let you know
Again Thank you
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post #4 of 7 (permalink) Old 12-07-2011, 08:48 AM
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Might want to put the year of your bike in your signature. It could help others diagnose your problems. If it's an early model, the plug wires might need replacing as well as the iridium plugs.

Not sure what type battery you bought, but an AGM battery has more cranking amps and won't spill acid all over the place. Deka and East Penn AGM batteries are good quality and made here in the USA. I started with a Chinese Scorpion AGM battery that didn't last very long, just long enough to be out of warranty!

I'm keepin' all the left over parts. I'm gonna use 'em to build another bike!
"Black Beauty"
1989 VN750 acquired December, 2008, 6,711 miles
Currently 23,298 miles

Old Blue
2001 Honda CMX250 Rebel acquired July, 2008

1987 VN750 project bike, acquired August, 2009, 33,000 miles and balancer sticking out of the case, currently awaiting attention and parts
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post #5 of 7 (permalink) Old 12-07-2011, 11:06 AM
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I'm going to agree to check Phantom out of Gas and try some Seafoam. Does it idle OK when you first start?

Regarding running out of gas at 1/4 tank. It may just be that you need to switch over to reserve when the tank gets that low. I'm not exactly sure where on the gauge you need to think about hitting reserve (I try mighty hard to avoid that).

If you don't know when/if the plugs have been changed on your bike, now might be the time (maybe even do wires/caps at the same time). Even if it doesn't cure the problem, it's a good idea.

Try those few things and let us know.
Good luck!

2005 VN750 upwards of 14K (haven't looked lately)

AGM Battery
Headers wrapped
Custom paint
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post #6 of 7 (permalink) Old 12-07-2011, 03:41 PM Thread Starter
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flite it is a 2002 with 35,000 miles bought it from a local dealer. I have only had it for about 3 months, they tested the battery and said it was ok, idk about that lol
I am trying the seafom on friday pay day, and plugs too

02' Kawasaki Vulcan 750
35,000 miles
Leather saddle bags
No mods
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post #7 of 7 (permalink) Old 12-08-2011, 12:46 AM
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Welcome. First of all, do you know if you have a CA model or a regular one? I live in AZ, and bought my '02 from an AZ dealer, but it was still a CA model. They can be sold in any state. Virtually all CA models are going to have tank venting problems. The easiest way to tell if you have a CA model is to remove the seat, and look at the rear of the tank. If it has 2 fittings on it, and 2 hoses, it is a CA model. If it has only one fitting and one hose, it is a 49 state model. If it is a CA model, the quick fix id to remove both hoses, and leave them off. If that makes a big improvement, then you can proceed to completely remove the CA evap system and solve the problem permanently. If you have a 49 state model, look under the gas cap, and find the little rubber grommet. Alcohol gas makes these swell, and eventually they swell completely closed. Remove the grommet, and see if that makes a difference. My '02 just passed 71,000 miles, I removed both the CA evap system and the complete air injection shortly after buying the bike. I had previously owned a '93, and already knew the problems these systems would cause.

You could also have plugged up or malfunctioning carburetors, unfortunately removing and reinstalling the carbs on a Vulcan 750 is not a pleasant experience, but it's not THAT bad if you take your time and do it the right way.

As for the fuel gauge, it could either be an inaccurate fuel gauge, or it could be a problem with the petcock. When you fill it completely up, put it in the "on" position, and set the trip odometer to 0, then see how many miles you get out of it before it quits. I've noticed on mine the gauge will show full for about 50 miles, then start to drop like crazy. Once at the halfway point, it drops even faster. But it still won't go on reserve until it shows empty.

Oh, and since you just bought the bike, I strongly suggest reading through the Vulcan Verses, they can be a big help. The Vulcan 750 is a real oddball motorcycle, there is nothing else like it anywhere. It has it's good points and it's bad points, but it is different. I would suggest you do the spline lube first thing, and check the condition of the splines. The other problems you are having can be fixed, but if your splines are chewed up, you have big problems. Also listen for any unusual rattling noises coming from the engine. That usually indicates failed cam chain tensioners, and can destroy the engine if run that way too long.

I am a motorcyclist, NOT a biker.

1997 Vulcan 750, purchased about a week ago
2006 Sportster 1200 Low
2013 Royal Enfield Bullet 500, converted to carb
2001 Yamaha XT225, heavily modified
2004 Honda Rebel 250
1979 Vespa P200E
2002 Vulcan 750 parts bike
1994 Yamaha XT225 parts bike
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