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Diesel Tech
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Okay, I'm a diesel person. Carbs are completely new to me. Other than riding my Honda Rebel as stock for a month, then ripping it out to install a Kubota diesel, I have never owned a gas engine.

High altitude 5000-8000ft, stock intake with K&N filters, and I might drill the baffles later. What jets do I need? What adjustments should I set?
 

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Super Moderator
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I would think the stock jets would be fine. Most folks only adjust the mixture screws to make the bike run richer, which is the opposite of what you'd need for high elevations.
For constant running at high altitude you would want a smaller main jet....and smaller pilot. But I can't say for sure what size would work.
Is the motor not running well? What do your plugs look like?
 

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Diesel Tech
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Its not running at all right now. The carbs are gummed up from 10 year old gas residue so I need to rear it down.
 

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I run an earshave with the Uni PK92's, and I rejetted with 142 main, 42 pilot, one shim each needle. At first I loved it because of how lean my clogged jets were making the carbs act, but I way overjetted and have lived with it more or less.

I am sick of the raw gas smell and rough throttle transition, though, and have ordered the jets to rejet down to 135 main (+1 on stock) and 38 pilot, then I'll play with the idle screws and maybe do something with the shims, not sure yet.

I plan to get to the jet covers with a small spanner and a stubby flathead, and believe I can access the left-side jets by removing the Cam Chain Tensioner. I'll fill in as I figure out how it goes once I get the parts installed and tuned a bit.
 

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Diesel Tech
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You just need a 7mm angle head box wrench. The only hard one is under the throttle cable bracket.
While you have it out, replace that one with a M3x0.8 cap screw to make everything easier. Same with the needle diaphragm cover screws.
 

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Premium Member
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DAMN 148 main is huge! So long as it runs well, that's what really counts. Then again I have a needle shim in mine, so maybe mine runs through the midrange as if it has such a large jet... I'm at sea level, too, and agree with you that these bikes were jetted super lean to meet EPA req's

As for the 132 being custom installed, I seriously doubt it. The airbox was still installed on this bike when I got it with 12k miles on it, and the carbs were absolutely gross inside, so I seriously doubt somebody had been in there before I went in for the earshave. I'm very prone to think mine was jetted 132 from the factory.
Yep, 38/132 is stock from the factory.
So says Clymer and also the numbers stamped on the jets in my carbs which have never been accessed by anyone but me since new.
 

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Figure I should follow up and say the re-jet went well, knocked it out a few days after my last post. 135 main 38 pilot, now I have to use my choke to start it (it could fire up without choke sometimes when cold, just goes to show you how incredibly rich 42 main is) but it behaves a little better and I think is a little easier on fuel. No noticeable performance difference, but I'm glad I did it and would advise most people not to re-jet for the earshave after knowing what I know now.
 

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Just wanted to add my recent experience with jetting and ear shave, hope it helps somebody. I ran stock jets for a while, 3 1/2 turns out on pilot air screws and 4 shims under the needle. Every now and then it would sputter at part open throttle. So I thought it was flooding with so many shims, wrong, took one out and it wouldn't run off of idle. Added one to each needle and it came alive! Except for now the sputter moved to full open. So I already have a set of jets, installed 40/140 jets and changed the shim count from 5 to 2 last night and man what a difference!! I admit I think I should have left the stock idle jets in, now it seems to hesitate returning to idle speed, but anything off of idle is SO much better than it was before. Luckily these bikes are pretty resilient and running a little lean for the last 1500 miles hasn't hurt anything major. Might try putting the stock idle jets back in, but might can tweak the pilot air screws to work with the 40's.
 

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UPDATE: Put the stock 38 pilot jets back in and idle is much better. Which makes sense, changes to intake wouldn’t affect the idle circuit, only the top air flow. Ran great yesterday, but i’m thinking it’s still a little lean on WOT. If I get a chance, I think I’ll put the 142’s in and drop the needle back down to stock position. The main jet only comes into play during the last 3/4 of throttle, the needle attributes to the first 3/4 more than the jet. Maybe i’ll Try it with the 2 shims in first then experiment from there.
 

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I’ve got stock air filters (that I want to keep) and Jardine drag pipes. It bogs down in 4/5/6 gears at about 4800 to 5200 rpm.
Any body able to give me a pointer?
I would suggest to try a couple shims under the needles first.
 

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I’ve got stock air filters (that I want to keep) and Jardine drag pipes. It bogs down in 4/5/6 gears at about 4800 to 5200 rpm.
Any body able to give me a pointer?
Are the carbs clean and the carb vent hose in the correct spot? Slide diaphragms good?
 

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FREEBIRDS MC CENTRAL NY
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I’ve got stock air filters (that I want to keep) and Jardine drag pipes. It bogs down in 4/5/6 gears at about 4800 to 5200 rpm.
Any body able to give me a pointer?
6th gear???????? Do you have a 700/750?

Sent from my Z899VL using Tapatalk
 
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