idles on one cylinder on cold start - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 9 (permalink) Old 04-06-2010, 09:23 PM Thread Starter
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idles on one cylinder on cold start

Hi, I did the ear shave and changed jets according to recommendations I saw. Bike runs great down the highway and at full throttle. I never sychronized my carbs yet. I'm having a problem of a hard start and only idling on one cylinder on start up. If I use almost maximum choke and let it idle high for only a few seconds it idles fine. and it will start fine when warmed up. I've adjusted the idle screws and doesn't seem to be the problem.
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post #2 of 9 (permalink) Old 04-08-2010, 05:22 PM
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Quote:
Originally Posted by nr5p View Post
Hi, I did the ear shave and changed jets according to recommendations I saw. Bike runs great down the highway and at full throttle. I never sychronized my carbs yet. I'm having a problem of a hard start and only idling on one cylinder on start up. If I use almost maximum choke and let it idle high for only a few seconds it idles fine. and it will start fine when warmed up. I've adjusted the idle screws and doesn't seem to be the problem.
Hello,
My bike was doing the exact same thing. I have a 2002, it was very hard to start, backfired a lot, and only ran on one cylinder unless I put the choke on about half way. I ran well above about 2000 rpm, but I had to use the choke on and off all the time. Since I did not trust my mechanical skills, I called the local Kawasaki dealer and brought it in for a tune up. The prognosis from the shop was dirty carbs, and after they rebuilt them, it starts with one flick of the starter, and runs smoother than ever. The mechanics advice was to periodically put stabilizer in the gas to keep the carbs clean.

Total bill for carb cleaning was $270.
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post #3 of 9 (permalink) Old 04-08-2010, 08:36 PM
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My '93 and '02, both bought new, have both done this from the very beginning if they sit for more than a couple of days. The carbs are clean. I use Seafoam for periodic maintenance. My belief is that gas evaporates out of one carb faster than the other, and it takes a couple of seconds for it to fill up. After that it runs fine. This seems to be a fairly common complaint with the Vulcan 750. I just learned to live with it. It starts running on both cylinders after the first couple of seconds, and runs fine after that, so I don't believe anything is plugged up. The Vulcan 750 has some really unusual carbs. One of these days, I will figure out how to replace that vacuum petcock with a manual one. Jerry.

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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post #4 of 9 (permalink) Old 04-09-2010, 10:13 AM
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I had my 750 for 3 years and never had a problem with it starting right up first try except for one time when I was out of town for training most of a month and a half in the winter of 08. I had left the bike with a nearly empty tank and had not put seafoam in for a while. Next ride the bike started fine but was running on one cylinder, unless I gave it some revs. I turned it off, pulled my can of seafoam out of the saddlebag and dribbled some in the tank and started it back up and limped out of the neighborhood. Once I pulled onto the main road and gave it some gas the other cyl kicked in. About a mile down the road I pulled into a parking lot and the bike idled just fine and was running fine again. Never happened again. Before that one time, and after, it always started on both cylinders and ran like new.

Of course, I got much more religious about adding seafoam to the gas, especially in the winter when my riding is more sporadic. I've had such fantastic results from seafoam, I wouldn't put anything else in my tank, period. Seafoam stabilizes gas for over two years.

If you need a stabilizer, use seafoam. If you want to keep your bike fuel system in good shape, use seafoam, religiously. I dribble some into every tank in the winter unless I'm on a trip, and filling up more than once a day. If I'm parking the bike in the winter I don't know exactly when my next ride will be because of weather etc. so I'll make sure there are a few ounces in my tank. Seafoam has NEVER let me down. I can not say that about other fuel stabilizers...

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Kyle, TX VN750.com member #707 VROC#19556
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post #5 of 9 (permalink) Old 04-09-2010, 11:26 AM
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I am now also a big believer in Seafoam, but rarely use it in the gas tank of the Vulcan, because I ride it often enough that I can't afford to, and always keep fresh gas in it. About every 3 months I soak the carbs in it, and then use the rest of the can in the next couple tanks of gas. I recently removed the carbs to rejet, first time they had ever been apart in 45,000 miles, and they were very clean inside.

Right now my XT225 dual sport, XR400 dirt bike, and TRX250 quad all have Seafoam in the gas, (2 oz per gallon) they are not getting used much right now, I also have battery tenders on the quad and XT, and start and warm them up once a week, to keep the seals from deteriorating, cylinders from rusting, and other bad things.


I also have a '72 Pinto station wagon stored in my garage, I am about to remove and clean the carb, fill the 16 gallon tank with gas, and pour in 2 full cans of Seafoam. Ouch $$$. I also start this car up at least once a week, warm it up, drive it around the block in my residential area, bring it back and park it. It is kept maintained just like it was being driven, lubricated, oil and coolant changed, tires kept aired up, etc. I would drive it if AZ ever comes out of the dark ages and stops emissions testing cars that old, like every other state in the country has done, including CA. Anyway, +1 for Seafoam. Jerry.

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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post #6 of 9 (permalink) Old 04-12-2010, 12:42 PM
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Had a similar problem (and similar thread here on the site). My front cylinder gradually got worse over ~6 months until it would not fire at all, had front carb cleaned ~$100 and bike runs great! I think it was the main jet specifically. I would have done the carb clean myself, but the bike was in storage ~300 miles from my house, so I had to take it to a local wrench there. Good luck.
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post #7 of 9 (permalink) Old 06-07-2010, 09:10 PM Thread Starter
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Still haven't figured this problem out. Real weird cause it idles just fine after holding the choke for a few seconds. Anyone have any other ideas? Could it be the float bowl level? I don't have a problem running outa fuel at top end or anything
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post #8 of 9 (permalink) Old 06-07-2010, 09:18 PM
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Have you synchronized the carbs and added Sea Foam yet?

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 #9 of 9 (permalink) Old 06-07-2010, 09:45 PM
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I have this problem with my 93' one cylinder firing, backfireing, having to use the choke even when it is warm, and is fine after reving it up. I have not checked which carb/cylinder it is. I'm intersested if it is the same cylinder on all of these bikes having the problem. I will be watching this thread to see the out come and if I find anything out will post it.

01' VN750
Jardine cross over exaust
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Modified seat and backrest
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Kumho 758 165/80-15 CT rear Dunlop 404 110/90-19 front
Coastered and air/fuel screws at 2.5 turns
Spline lube

93' VN750 getting TLC
Decals and mirrors
Coastered and air/fuel screws at 2.5 turns
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