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Can anyone help with the location of the air/fuel mixture screws on a '01 vn750 ? It's cutting out at around 4000rpm after being fitted with K&N air filters. I think it may need to run a little richer. here are photos of the Keilin carburetor.
Thanks.
 

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Can anyone help with the location of the air/fuel mixture screws on a '01 vn750 ? It's cutting out at around 4000rpm after being fitted with K&N air filters. I think it may need to run a little richer. here are photos of the Keilin carburetor.
Thanks.
Once you start modifying the bike you have to do something with the carbs. You are probably running lean and need to do something about it or damage will occur . Some kind of dyno tune kit may be what you need, or put it back stock. Here is one of many that maybe what you need.

https://www.ebay.com/itm/Kawasaki-VN-750-cc-VN750-Vulcan-6-Sigma-Custom-Carburetor-Carb-Stage-1-3-Jet-Kit/332145362962?epid=1855254360&hash=item4d55680812:g:oK8AAOxyLiJR1ENy&vxp=mtr
 

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The fuel/air mixture screws are behind a foil covering so look for that. You can CAREFULLY remove that foil covering to reach the screw. (This is assuming that the original settings have not been messed with by a previous owner. The factory "sealed" them behind the foil. If you don't see that foil then someone, during the history of the bike, has already messed with them.)

When you start piddling with the fuel/air screw you have to be easy on it. Its really easy to over-power doing it and stripping it.

Make sure that you first and foremost determine the "base" setting. By that I mean find out exactly how many turns out it is from bottom.

Mark with a dab (small) of paint, or some visible marker, BEFORE you start to turn it. This is so you can return it to the original setting if you need to. Then turn it GENTLY until it bottoms out WHILE COUNTING the number of turns you make. A GENTLE snug is all that is necessary (DO NOT torque it down).

It'll probably be only one to two turns out in the stock setting.

Then bring it back out exactly to where it was originally and make quarter turns out only. See how it runs with each minor adjustment. Don't do more than a quarter turn at a time, better yet probably an eighth of a turn would be advisable.

You'll probably never need to go beyond 2.5 turns out from stock.

Just for giggles, before you try changing the fuel/air mixture, I'd pull the main jets from each carb (Yes, they can be pulled with the carbs still on the bike.) and soak them in a quality cleaning solution. I did mine in some SeaFoam. The main jets start kicking in around 4K to 4.2K rpm and if they're dirty the bike will start to stumble at that engine speed. Any rpm under that 4K-ish rpm is handled by the other jets (pilot jets).
 

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Slight clarification on what I said above: Once you return the screws to their original number of turns out, FROM THAT TIME ON, make only the quarter or eighth turns outward.
 

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Another clarification: You'll probably never have to go more than 2.5 turns out from the bottom! (Not from the original setting)
 

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Hey RedHorse..... did you get the carbs done?
 

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Good. There really aren't many times when you'd need to mess with the fuel/air ratio. Even should you put better exhausts on it all you'd need is juuust a smidgeon of richening. Adding better air filters probably won't change things enough to warrant a fuel/air alteration. Even if you do I'd make no more than an 1/8th of a turn change at a time.

Happy to hear it is running better now.

If you have any more questions on it, just ask away!
 
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