Throttle kills engine - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 19 (permalink) Old 08-30-2011, 01:47 PM Thread Starter
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Exclamation Throttle kills engine

Okay here goes. Yesterday my '01 750 dies at a stop light, wont restart. Just got it 3 weeks ago from a guy who barely rode it. Been sitting for a while. Last few days was really hard to start i.e. would crank till 1 cylinder got to t.d.c. or close then would stop. almost like there was to much pressure.

Anyway last nite tore out the carbs and cleaned them, individually as to not mix and match parts. Carbs were filthy both needle float valves were gunked up (explains leaking carb also yesterday). Jets were okay cleaned really well. All areas cleaned.

Put it all back together and started it this morning and wow it cranked right over no problem. Took a few cranks to get the gas flow again but started with the choke on and idles better. However now the problem is that if I even touch the throttle even a little r.p.m.s drop instantly and kills the engine. Checked plugs saw was running way rich and brought screws down to 2.5 turns also.

Any and all help is appreciated. I am working on a really low budget so any tips tricks or other info to cut costs are welcome (except at the cost of safety).

Last edited by 2P.eagle2; 08-30-2011 at 02:30 PM. Reason: adding info.
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post #2 of 19 (permalink) Old 08-30-2011, 02:36 PM
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Sounds to me like you still have carb issues.

To save you the trouble of taking them back off, try disconnecting the fuel lines, draining the carb bowls, and pour Seafoam down the lines to fill the bowls. Let it sit a good while (at least a day), then drain the bowls again.

Tank mix some more Seafoam (I use about 1/3 of a can to a tank of gas when I suspect dirty carbs) and start the bike. Let it idle until it gets up to temp, then slowly play with the throttle, and if you get any improvement, hold it there a while to let the fuel flow.

If that gives you no love, you'll probably need to pull the carbs again.
Clean everything all over (even if you think it was clean before), and blow out all jets/passages with compressed air.

Good luck!
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post #3 of 19 (permalink) Old 08-30-2011, 02:39 PM Thread Starter
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Thanks will give it a try. and post here with the results.
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post #4 of 19 (permalink) Old 08-30-2011, 03:12 PM
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Just a couple of points ...

When you are re-assembling the carbs, make sure you turn each vacuum piston spring seat so that the small hole in the bottom of the vacuum piston is not blocked.

When you get it all back together, make sure your choke plungers are fully seating when you remove the choke. Actually, there is no choke butterfly on our carbs. The choke is merely opening another valve and letting more gas be delivered to the throttle body. If you can not lean out your mixture with the air/fuel mixture screws, there may be a problem in this area.

~~C8> Ratt
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post #5 of 19 (permalink) Old 08-30-2011, 03:32 PM
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check your boots and hoses for proper placement and no leaks
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post #6 of 19 (permalink) Old 08-30-2011, 03:33 PM Thread Starter
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thanks Z plan a and plan b. I think you may be on to something with the choke plungers. Can you explain a little more on how that would effect the problem i'm having?

I can do anything I like striving for the knowlege of why, if you don't mind please...
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post #7 of 19 (permalink) Old 08-30-2011, 03:35 PM
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I just went through this on my bike, but mine was just one cylinder, i could start it on that cylinder but as soon as i hit the throttle it would die, on mine it ended up being the little plastic thing that went down over the top of the needle (at the bottom of the spring) was getting stuck. i tok it out and messed with it a bunch, swapped it with the one on the good cylinder and for now its fine, I know it will do it again eventually but for now its working.

what i did temporarily last time it happened was used the aerosol seafom and sprayed up into the carb drain and that would dislodge it for a little bit.

Maybe take the carb out and just run that spring up and down and see if the plastic catches.

1992 vn750, 16000 miles
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post #8 of 19 (permalink) Old 08-30-2011, 04:03 PM
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Quote:
Originally Posted by 2P.eagle2 View Post
thanks Z plan a and plan b. I think you may be on to something with the choke plungers. Can you explain a little more on how that would effect the problem i'm having?

I can do anything I like striving for the knowlege of why, if you don't mind please...
plan a was to address the throttle issue. That little plastic thing Todd speaks of is the vacuum piston spring seat.
plan b was just info in case you couldn't lean the mix out. It is another way for fuel to enter the carb throat if the seat of the choke valve is fubar or the choke pistons don't move freely in the carb body. I'm no guru, just throwin' stuff out there for reference.

~~C8>
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Last edited by ZCraggRatt; 08-30-2011 at 04:06 PM.
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post #9 of 19 (permalink) Old 08-30-2011, 09:22 PM Thread Starter
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Thanks again for the ideas... Back to work will let you know how it goes.:
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post #10 of 19 (permalink) Old 08-31-2011, 04:06 PM Thread Starter
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Okay seafoam appeared to work great... for a minute Started really easy, idled fine, let it warm up, throttled up, all still okay, tried to go down the street shifted fine turned the corner sputtered and died. So project for now pull em again tonite clean em again make sure hole under main jet spring is clear and check choke plungers for free movement.
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