Ok so got carbs cleaned now have a rev restriction >??? - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 22 (permalink) Old 06-21-2009, 03:26 PM Thread Starter
 
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Ok so got carbs cleaned now have a rev restriction >???

Ok so Cindy AKA Corbin just came over and installed freshly cleaned carbs....but now we are a little stumped on a new problem that the bike did not have before....

the bike runs,idles,starts fine but when opening the throttle up it is like there is something restricting it at about 4kRPM it clears up within a few minutes and will go all the way up...

However when riding the bike it will not go over 4k RPM for nothing. it will bog down (not stall) and is jumpy....

here is what was done up to this point.

Fresh Gas w/Seafoam
New Plugs for advanced auto (may be gapped wrong or even wrong plugs)
New Air filters treated with PJ-1 ?
Carbs broke down cleaned and put back together. (thanks to Corbins365)

before all this the bike ran but had no power, but did not have a RPM problem... after seafoam treatment I think so of that nasty gunk build up broke lose and clogged up the carbs, they then started to flood.

I am going out now to test spark on all plugs....but if anyone has any other suggestions or had this same problem and knows main thing(s) to check please please help....I wanna feel the power of this bike!!!
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post #2 of 22 (permalink) Old 06-21-2009, 03:33 PM
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Did you leave a Vacuum line off?

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post #3 of 22 (permalink) Old 06-21-2009, 03:59 PM Thread Starter
 
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Ok so I just went out and check all plugs 1 by 1.....

the plugs on the rear head (pointing towards the rear) are already black.

the plugs by on the front head (pointing towards the front) look brand new.

All plugs had spark but not strong..... is it possible that I have the wrong plugs because I got them from advanced Auto....

and why do the front plugs look brand new and the rear are black already ?
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post #4 of 22 (permalink) Old 06-21-2009, 04:06 PM
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What I think is that the rear carb is flooding out. The float is too high, could be trash in the seat, float sticking and not shutting fuel off.
Also check the vaccuum hose to the petcock. Cracks in the hose can keep the petcock not work right, not allowing enough fuel to the carbs.
Hope this helps you.
James

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post #5 of 22 (permalink) Old 06-21-2009, 05:05 PM
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Let's see if we can eliminate a few things:

Dave's plugs are Autozone 4164s- just checked what I have in the garage and those are the right replacments for the VN750. So it's not the plugs.

Carbs were completely torn down and cleaned, top to bottom. Pics are in my gallery - 4 sessions. When I pulled them apart there was a piece of mung on the right float needle, which apparently was causing Dave's previously problem with flooding. Cleaned all that out - kept the floats and needles out, hit the float bowls with Gumout, compressed air, more Gumout, ad nauseum until there was nothing to be seen in there. Reassembled last night, ran 'em on my bike, and they idled fine.

Put 'em on Dave's bike this a.m. - all boots were firmly on, new (oiled) aid filters, vac lines on front and rear carbs...once the bike started, it was doing exactly what Dave describes: idling fine, but when opening the throttle (in the parking lot), the rpms would get up to 4-4.5K, and then drop down to around 2K. Lots of popping and junk burning out of both exhaust pipes. Then after about 5 min, that stopped - opened up the throttle to 7K+, and it was idling fine. Did that a few times, and we never had troubles with that restriction again....until, of course, I headed back to the mountains (doh!).

Soooo, I'm confident that the carbs are as clean as two carbs can get, but it could be a float height problem if I didn't put them in evenly (altho' I can't find anyone that's talked about that here on the Forum). Dave's previous air filters had blown themselves to bits, and it's possible that there are parts of the filters sitting in the airbox (or, shoot maybe in the carb bellmouths now) that are causing intermittent restrictions. In fact...that could be a real possibility. If the filters "blew up," as it were, how the heck does one check to make sure all those bits are really out of there?? Pull the air filter housing units, carb boots, and emissions hoses, and hit the box with compressed air?

C
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post #6 of 22 (permalink) Old 06-21-2009, 06:31 PM Thread Starter
 
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Ok....So I just checked all lines and all seem to be well.....So after sitting and thinking and thinking.....


Could it the Sliders (plungers) are not rising fast enough ?

Maybe due to maybe Restricted Air Intake
Poor Vacuum
Clogged jets again ???
or maybe even a leak on the diaphragm ?

I don't want to or really think it is inside the carbs and trying to deal with everything but having to take them off again.

So my questions now would be how can I find out if its....

restricted Air Intake ?

Poor vacuum ?

I also just talked to my step dad who said is sounds like a air/fuel issue. The color of the plugs will tells us if the mix is lean or rich. It would be if lean; very light brown to almost whitish (most likely) or the exact opposite sooty black (least likely)

However my rear plugs are black and my front plugs like brand spanking new....when they are all new. SO where does that leave us because that was a question he had no answer for....LOL....it's almost there, once this quirk is worked out i will ride it like I stole it for sure!!!!

Last edited by daddydave325; 06-21-2009 at 06:33 PM. Reason: add
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post #7 of 22 (permalink) Old 06-21-2009, 06:59 PM
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I know this carbs are very hard to get clean also it seems that just a little bit of trash will clog them.
I had to go over some yamaha carbs 3 times to get them cleaned well enough for them to run right.
Did you clean the fuel tank?

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post #8 of 22 (permalink) Old 06-21-2009, 07:21 PM
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Open the gas cap to make sure you good ventilation, you could have a clogged tank vent.


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post #9 of 22 (permalink) Old 06-21-2009, 07:26 PM
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Quote:
Originally Posted by niterider View Post
What I think is that the rear carb is flooding out. The float is too high, could be trash in the seat, float sticking and not shutting fuel off.
Also check the vaccuum hose to the petcock. Cracks in the hose can keep the petcock not work right, not allowing enough fuel to the carbs.
Hope this helps you.
James
I think niterider is on the right track, when the rear cylinder is so wet and black, and the front cylinder is clean and burning right. Something is not right in the rear carb, or some of the old foam filter is sucked in there as Cindy surmises.

Cindy, just a note regarding the spark plugs, just because they are new, doesn`t mean they are any good. I think I read a post here just recently from somebody who installed new Champion (?) plugs on his bike and it ran like crap. Put on some new NGK plugs, which are recommended for this bike, (and I don`t recall if they were Iridiums or not), and it ran like a champ.

Likewise my next door neighbor, who was an experienced auto mechanic, installed some new Motomaster plugs (a cheap Canadian Tire Co. house brand ) in his 850 Suzuki one weekend, and the bike would hardly run. He swapped them out the next weekend after 4 round trips to Calgary, and about 1,000 miles on the plugs. He put in a name brand, maybe Champions, and it ran like a new bike. Some engines, or makes of engines, just seem not to run right with some brands of plugs, whether they are the suggested replacement part or not. I do not know why, I just know that in my experience, it is true.

I hope you find and cure the problem without too much more grief. This is the time to be ridin`, not wrenchin`.

Gordon

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post #10 of 22 (permalink) Old 06-21-2009, 07:40 PM
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Is your exhaust on the rear cylinder restricted,what goes in must come out.




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