One cylinder firing, other intermittant - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 14 (permalink) Old 03-10-2011, 02:38 PM Thread Starter
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One cylinder firing, other intermittant

Greetings all, first time question. The original problem was that only one cylinder fired, took out carbs, cleaned reinstalled and now situation reversed! Replaced carb holders (manifolds), thought that would be the problem, as we sprayed some WD on the rubber and the RPMS increased. Anyhow, it starts easier, but only on one cylinder. Battery is new. Have noticed one item, with the engine running we have one vent hose, that if I blow into it, the RPMs increase. That hose "T"'s off and goes to each carb. Question: are there any hoses that are not connected to anything? Have I missed a connection? is there a hose that is connected to the appliance that is under the tank where the fuel guage wire comes out?? Is this where that vent hose goes?? Any help would be greatly appreciated. Tks J
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post #2 of 14 (permalink) Old 03-10-2011, 04:08 PM
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Welcome to the Vulcan madness.

vent hose goes to the right ear -air filter housing
https://www.vn750.com/photopost/showp...o=1757&cat=503

Is it the front or rear cylinder that is not firing?
Is the tach working? It senses electrical pulses from the front coil.

Check plugs for bright blue spark
Are the high tension wire boots pushed on tight on the plugs ?
Are the ignition coil trigger wire connections clean and tight?
Are the plug wires touching throttle cables or the frame and grounding out?

Can`t help with emmisions hoses, as my Canadian bike doesn`t have all the emmissions crap on it.
It`s good to be Canadian! lol

Gordon

1991 VN 750 -"Cosmic Lady" or "Bad Girl"?
Purchased May 16, 2008
Approx.19,300km (12,000 miles)

H-D windshield
Relocated R/R
MF-AGM battery
Fiamm Freeway Blaster horns
F&S luggage rack and engine guard
Kury Offset Hiway pegs
July 13, 2016, Riding on the DARKSIDE now, Classic Radial 165/80-15


TOP TEN THINGS A NEW RIDER/OWNER SHOULD DO. Click on link.
https://www.vn750.com/forum/11-vn750-general-discussion/9127-top-ten-items-you-would-suggest-new-owner-do-his-new-ride.html
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post #3 of 14 (permalink) Old 03-10-2011, 07:36 PM Thread Starter
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We found where the vent hose goes, and we are getting spark from all plugs. it seems we are getting too much air. Shot some WD on the carb holders and the RPMs went up. tightened the clamps and it seems not to help at all. When we block the carb throat, the RPMs increase also. Right now, we get both cylinders to fire, but not steady. Have the fuel adjustment at approx 2.5 turns and it seems not to make a difference if we adjust it while it is running. Most times it is hard to start. Also, sometimes when attempting to start, we see fuel being ejected from the carb throat. At a loss on what to do net.
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post #4 of 14 (permalink) Old 03-10-2011, 08:19 PM
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Quote:
Originally Posted by jayinjax View Post
We found where the vent hose goes, and we are getting spark from all plugs. it seems we are getting too much air. Shot some WD on the carb holders and the RPMs went up. tightened the clamps and it seems not to help at all. When we block the carb throat, the RPMs increase also. Right now, we get both cylinders to fire, but not steady. Have the fuel adjustment at approx 2.5 turns and it seems not to make a difference if we adjust it while it is running. Most times it is hard to start. Also, sometimes when attempting to start, we see fuel being ejected from the carb throat. At a loss on what to do net.
Since you had the carbs out, you may need a carb sync to balance the vacuum between them too.
Never done one yet myself. What say the other more experienced wrenches out there?
https://www.vn750.com/forum/showthread.php?t=1084

Gordon

1991 VN 750 -"Cosmic Lady" or "Bad Girl"?
Purchased May 16, 2008
Approx.19,300km (12,000 miles)

H-D windshield
Relocated R/R
MF-AGM battery
Fiamm Freeway Blaster horns
F&S luggage rack and engine guard
Kury Offset Hiway pegs
July 13, 2016, Riding on the DARKSIDE now, Classic Radial 165/80-15


TOP TEN THINGS A NEW RIDER/OWNER SHOULD DO. Click on link.
https://www.vn750.com/forum/showthread.php?t=9127

Last edited by OlHossCanada; 03-10-2011 at 08:23 PM.
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post #5 of 14 (permalink) Old 03-11-2011, 10:27 AM Thread Starter
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OK, so last night we took off the carbs and checked the carbs, they were clean. we took off the carb holders and noticed we had the F on the R and changed them. Don't ask why, they look exactly the same. Anyway, we put some goop on the holders and reattached the carbs. put everything back on and Voila, it was still running like crap. It is getting too much air. Sprayed the holders and the RPMs went up. Cannot believe we have a leak there. The clamps are tight and secure. We cannot even move the carbs, they are so tight. It cannot be the vacuum lines, as we changed those, as wellIs there anywhere else where an air leak can occur?? Any help would be greatly appreciated as Bike week is upon us and I have a visitor who needs a ride!!! Tks J
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post #6 of 14 (permalink) Old 03-11-2011, 11:01 AM
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You are testing without the air filters? Without the filters it won't run properly. If you have the original jets in the carburetors, you need to have the original 'ear' filters. Some have changed to pod filters, which requires changing the jets.
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post #7 of 14 (permalink) Old 03-11-2011, 11:16 AM Thread Starter
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You are testing without the air filters? Without the filters it won't run properly. If you have the original jets in the carburetors, you need to have the original 'ear' filters. Some have changed to pod filters, which requires changing the jets.
yes, testing it without the air boxes connected. Have the originals, but am a bit confused as to how that would make a difference. Anyhow, will try that right now and get back to you on how it works. Perhaps the restriction will make the difference! and thanks for the return. J
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post #8 of 14 (permalink) Old 03-11-2011, 01:07 PM Thread Starter
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well, we connected all the air delivery units and it did run ok, hard to get an idle, but it ran down the road with some gusto. brought it back, shut it down and changed the oil. After that, it wouldnt start. we now have it hooked up to a charger. It is a new battery, but it doesnt seem to have the kick that is necessary. Thanks for the tip !!! I was ready to get the backhoe out, dig a hole and bury it. Next is to wait for the charge, start it up and go for a longer ride and hope it doesnt stall before we get back!
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post #9 of 14 (permalink) Old 03-11-2011, 01:16 PM
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Lead/Acid Battery or Maintenance Free? if its a regular wet cell you will all ways have hard starting issues... Now that you have the filters back on, try adjusting the carbs again... not the little black knob, but the actual air idle screws.
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post #10 of 14 (permalink) Old 03-11-2011, 06:34 PM Thread Starter
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Well, gave the battery a charge and was not satisfied with the results. tested the battery and decided to bring it back, they tested it and said it was junk and offered another. we declined, took the cash back and went and bought a MF at the battery store down the road. It is now being charged and we will probably be finished with the problems we have been dealing with. Will let you all know how it works out and want to thank you for all the words of wisdom. Great forum, wthout it, would never have been able to get it started!!! Have a good one. J
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