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Discussion Starter · #1 ·
Hey folks,
I just finished doing the ear shave, taking the EPA stuff out and the goats belly removal (stock pipes) but am now having a heck of a time finding the correct size jets. I must've thrown at least a centimeter's worth of spacers on the needles but the plugs are still showing lean at idle. I've tried all but completely closing the pilot air screws.

HELP!

On a side note - isn't there some way to compute jet sizes? Is guess (or listen to what other's have used) and check the plugs the only way to go about it?

Michael Smith
93 VN750
 

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The only other way other people talk about is to use a Dyno with an exhaust gas analyzer probe. It helps limit the guessing but is $$$.
 

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Umm. Correct me if I'm wrong.
I don't believe we have pilot air screws on the VN750. Aren't they idle mixture screws, and we turn them out for richer idle mixture, and in to make it leaner?
 

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Discussion Starter · #4 ·
The repair manual (its not clymers..the other brand..i forget) refers to the part as the air pilot screw. Thats what I was going off of.

But good news. My buddy finally got sick of my bike taking up space in his garage so he took over.
A carb-synch, slight jet adjustment and 6 washers on the needles later and I'm up and running.

I'm not getting as good as gas mileage as I used to (running a bit rich), but at least I'm tweaking the bike instead of just trying to get the stupid thing running!
 

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NYgoneCA said:
The repair manual (its not clymers..the other brand..i forget) refers to the part as the air pilot screw. Thats what I was going off of.
This is correct...they are pilot air screws, according to Clymer's. They control A/F mixture at small throttle openings. I'm not sure if they do this by restricting air, or by adding fuel or vice versa, all I know is that turning them CW leans out the mixture, CCW enrichens it. That's why we turn them out after 'coastering' and removing the EPA crap..to lessen the popping because of lean mixture when the throttle is closed.
NY... our stock main jets are 132s, and I've heard riders using anywhere from 140 to 160 w/ the ear shave. There's lot of info on VROC and in our Yahoo group re sizes, needles etc. Check it out...
My intake & carbs are stock except for K&N air filters...I've not done anything because I was afraid of exactly what you've posted, and the Vulc runs great, a little on the lean side, but great. Because the main jets are easy to change, I am going to go up to 135s soon just see if I can remove the very slight popping I still get after yanking the EPA crap and turning the mixture screws out to 2 3/4 turns. I figure that small of an increase won't hurt anything, and the bit more fuel could even be a good thing...
 

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Carb Jetting

You can go to a Kawasaki Dealer and get a jet kit. Not one availible in Dyno-Jet. I did an earshave with K&N filters and put Vance&Hines Cruzers exhaust on, and this is what I used for Jetting. 2 shims under each needle valve and 140 main jets "small round". I also ran the fuel air mixture screw in all the way and then backed it out to 1 1/2 turns. I then started the bike and warmed it to operating temp and adjusted the Idle and then tweaked the fuel air mixture screws until the idle picked up. Now just turn it in or out until the idle picks up and note the position "turns out on the screw". Do this for both carbs and re-set the idle, and that should work for you. Something else I'd like people to know is that the fuel/air mixture is usually for Idle and low RPM accel. The needle valves are for your mid range, and the main jet is for wide open throttle. Hope this helps you out!
 
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