Ok I give, Uncle... Uncle!!! - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
Carbs and Fuel System
From the gas tank to the carbs
All fuel system discussion

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post #1 of 26 (permalink) Old 11-02-2012, 11:42 AM Thread Starter
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Ok I give, Uncle... Uncle!!!

Hi all,

Itís been quite a few years since Iíve been in the forum, ever since a pickup truck took out my 86í about 6 years ago. But I know this to be a veritable gold mine of knowledge and information and so I turn humbly to your wisdom for help. Please forgive the following novel, but itís as concise as I could tell it. For the last two seasons Iíve been riding a like-new 94í Vulcan 500 which was perfect in every way, and I just sold it to buy another 750 (1989) with some nice change left over. It was almost three hours away from me, and after conversing with the owner over the phone, I learned it ran great and he commuted on it an hour to work often and it just had a few cosmetic items to clean up. Turns out his definition of ďgreatĒ is far from mine. I did buy it though and rode it back the three hours home. It actually rode fine on the highway, but I knew it needed carb cleaning because the tank was rusty inside and it idled high and needed a lot of throttle to take off without bogging out.
Once home I pulled off the gas tank and got all the rust out I could. The screens on the petcock were fine, so I didnít think much rust would have gotten in the carbs, so I just dumped a half can of seafoam in the gas to try and clean them out. Problem was, after that, it took half the host of heaven to get it to start, and then even after warming up for 20 minutes I could never make it half way around the block without it dying and having to walk it back home (wouldnít restart). Plugs were always wet when I pulled them out. So I pulled the carbs and found one pilot jet partially clogged and the other totally clogged. I cleaned them out with a stick pin (tiny tiny hole in there), and cleaned everything else on the carbs with the exception of taking them apart and looking in the float chamber (I know, I know). But I reasoned that the floats didnít sound stuck, and when I used a clear hose to check the fuel levels on the bike, it looked to be within range, so I filled them with pure Seafoam and let them soak 24 hours before reassembling the whole thing. Afterwards it started easier than before (easier being a relative term) and definitely ran better once started, but no matter how long I warmed it up, it still stalls halfway around the block, leaving me walking home.
So I went out and in great pain parted with a hundred dollars for a Deka AGM maintenance free battery and NGK Iridium plugs. I also ran the meter over my R/R and Stator and both seemed to test fine. I installed the battery and plugs and then also decided to do the adjustment procedure noted many times in the forum on my air fuel screws. After removing the plugs and turning them in then backing them out 2.5 turns, I tried to start. Cranks much faster, but no start. After cleaning the carbs and before I replaced the battery and plugs and set the A/F screw to 2.5 out, it would start right up and run with a shot of starter fluid, but now a shot will start it and run for about 4 seconds and then die again (I hate using that stuff, but I also hate running my starter for an hourÖ 6 in one hand half a dozen in the other). I figured maybe 2.5 turns is not right for me, so I checked the manual and it says 1 5/8 turns, so I did thatÖ no change.
So to recapÖ

1. When I picked it up, it ran crappy but I did manage to ride it 120 miles, shutting it off and restarting three times along the way. Once home I could get it to start only after an hour of cranking but couldnít get farther than half a block.

2. After cleaning the carbs and reinstalling, it ran better but still couldnít break the half block barrier without dying no matter how much warm up.

3. After new AGM battery and iridium plugs and fiddling with the Air Fuel screw, still not starting and even after starter fluid wonít idle.

I wish I had got a good count on the A/F screws when I turned them in, but theyíre not easy to reach on the bike, and I kept dropping the screw driver and losing count, so I just stopped trying and focused on the 2.5 out. From this mess can anyone see any obvious things that I can turn to next? Iím feeling very defeated by this . Thanks in advance for any help.
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post #2 of 26 (permalink) Old 11-02-2012, 12:15 PM
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Check or replace the vaccuum carb hose to the petcock.

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post #3 of 26 (permalink) Old 11-02-2012, 12:33 PM
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From this mess can anyone see any obvious things that I can turn to next? I’m feeling very defeated by this . Thanks in advance for any help.
Quote:
but I knew it needed carb cleaning because the tank was rusty inside and it idled high and needed a lot of throttle to take off without bogging out.
Quote:
so I just dumped a half can of seafoam in the gas to try and clean them out.
....just a thought....
By dumping a half can of Seafoam in the tank, may have re-created previous problem.
Seafoam will/may clean any remaining rust in tank plugging up Petcock, screen, carbs.

Good decision on the AGM Battery and Irridiums !
hope this helps...
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post #4 of 26 (permalink) Old 11-02-2012, 01:43 PM Thread Starter
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Thanks for the ideas, to address both the Seafoam and the vac line points, I did look over the petcock vac line and it looks good. In fact, everything I'm seeing seems to point to too much gas as opposed to too little e.g. any choke will kill it when it's idling and the plugs are always wet when I pull them. As for the seafoam stirring up more rust from what's left, that's totally possible, but the petcock screen seemed really fine, so I didn't think anything damaging could get through it. I dread having to pull those carbs off again, but if I have to I will. The carbs on my Vulcan 500 were like walking barefoot in the sunshine in comparison.
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post #5 of 26 (permalink) Old 11-02-2012, 02:06 PM
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ok im gonna think out loud here plugs are wet carbs are for the most part clean

what does an engine need to run
fuel <--- looks like we got that
air <---- oh snap gas doesnt burn without that huh how are the air filters take them off and try running it
need an ignition source wait its coming to me oh yea spark plugs <---- new ngk iridiums installed yes yes but are they getting enough spark to them check for voltage at the power wire on the coils if it is less that 12 volts with key on engine off and a fully charged battery try the ignition coil relay mod
and if all that doesnt work i would check compression just to ease my mind i would say its good since you already logged 120 miles on the bike also you may need to adjust your idle screw in or out

im not bustin your balls on this in fact i had the same kinda problem when i first got black betty and it was the coil mod that worked for me

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post #6 of 26 (permalink) Old 11-02-2012, 02:27 PM
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ok im gonna think out loud here plugs are wet carbs are for the most part clean

what does an engine need to run
fuel <--- looks like we got that
air <---- oh snap gas doesnt burn without that huh how are the air filters take them off and try running it
need an ignition source wait its coming to me oh yea spark plugs <---- new ngk iridiums installed yes yes but are they getting enough spark to them check for voltage at the power wire on the coils if it is less that 12 volts with key on engine off and a fully charged battery try the ignition coil relay mod
and if all that doesnt work i would check compression just to ease my mind i would say its good since you already logged 120 miles on the bike also you may need to adjust your idle screw in or out

im not bustin your balls on this in fact i had the same kinda problem when i first got black betty and it was the coil mod that worked for me
I am all for the coil mod.
I placed Battery voltage level on my coils anytime ignition switch is on (connected to battery).
....guaranteed full/best spark possible
Also, clean 12v connections on coils.
WilliamTech

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...have a vulcan good day!
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post #7 of 26 (permalink) Old 11-02-2012, 04:12 PM
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I wouldn't mess with any thing but the fuel system right now.You started with a fuel problem and after working on it ,the symptoms changed, indicating to me you are working on the right system. Pull your carbs, completely dissasemble them,including removing the floats and needles this time,wash every thing out good and check your needle valves for wear.Even a little ring around them will often cause the carbs to flood.

After you are done with the carbs turn the mixture screws in till they seat and back them out 2.5 turns and it would be best if you could clamp them in a vise and use a bottle with a hose teed to each float bowl bench test them for proper fuel level in the bowls.You should be good if you don't bend the tabs on the floats.

After you reinstall them on the bike ,hook it back up to the same bottle you bench tested it with and fire it up.Let it warm up and see if it idles smoothly and revs smoothly with the tank and petcock out of the picture.

If it runs right i'ts time to give the tank a thorough cleaning and the petcock as well,install a couple of inline fuel filters on the fuel lines when you reinstall the freshly cleaned tank.

While you are at it since you installed a new battery make sure all the grounds are clean and tight.There are several to check find all of them including the one to the engine.Hope this helps




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post #8 of 26 (permalink) Old 11-02-2012, 04:27 PM
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Quote:
Originally Posted by denny6006 View Post
I wouldn't mess with any thing but the fuel system right now.You started with a fuel problem and after working on it ,the symptoms changed, indicating to me you are working on the right system. Pull your carbs, completely dissasemble them,including removing the floats and needles this time,wash every thing out good and check your needle valves for wear.Even a little ring around them will often cause the carbs to flood.

After you are done with the carbs turn the mixture screws in till they seat and back them out 2.5 turns and it would be best if you could clamp them in a vise and use a bottle with a hose teed to each float bowl bench test them for proper fuel level in the bowls.You should be good if you don't bend the tabs on the floats.

After you reinstall them on the bike ,hook it back up to the same bottle you bench tested it with and fire it up.Let it warm up and see if it idles smoothly and revs smoothly with the tank and petcock out of the picture.

If it runs right i'ts time to give the tank a thorough cleaning and the petcock as well,install a couple of inline fuel filters on the fuel lines when you reinstall the freshly cleaned tank.

While you are at it since you installed a new battery make sure all the grounds are clean and tight.There are several to check find all of them including the one to the engine.Hope this helps
good advice on how to take care of the carbs

what i suggested is a very simple way to make sure that the problems are caused by the carbs and since i went thru all of this with my bike when i first got it i only point out that why remove the carbs again in the chance that they might be the problem when you can check the air filters and test voltage at the coils in about 15 mins and if they all check out you would already have the seat, side covers and neck covers and air filters out of the way for a carb pull

so for the op i will rephrase

you might as well check the things i listed on the way back into another carb pull

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Sucks getting old but it beats not getting old.

i got my helmet but it sure makes licking the windows a chore

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post #9 of 26 (permalink) Old 11-02-2012, 07:09 PM
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Just offering a tech tip here.
Mark your screwdriver with two different colored dots of paint (or similar) 180 degrees opposite each other on the handle or shaft to simplify counting turns out on the air/fuel mix screw.
This idea did not originate with me but with a member who was an auto tech and who specialized in rebulding carbs.

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post #10 of 26 (permalink) Old 11-02-2012, 07:13 PM
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Originally Posted by OlHossCanada View Post
Just offering a tech tip here.
Mark your screwdriver with two different colored dots of paint (or similar) 180 degrees opposite each other on the handle or shaft to simplify counting turns out on the air/fuel mix screw.
This idea did not originate with me but with a member who was an auto tech and who specialized in rebulding carbs.
I like that !!!

WilliamTech
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