Jet Size flow rates

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Ryce

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Years ago I found a lot of KZ's , GS's etc that had main jets and pilot jets drilled over size. So I used a syringe to measure the flow rate by passing the fuel (by gravity) through the jet ( for example 10 CC) then count the seconds.. till the tube was empty. I could sort my collection of jets and get a pretty close flow rate match, no matter what the jet # was stamped on the jet.

I don't remember now. But thought the Mikuni jets were numbered based on flow and the Keihin Jets were stamped based on the dia. of the hole. Does anyone know what the numbers actually indicate? I am not sure what the numbers on the air (pilot) jets indicate.

Thanks for any info.

Ryce
 

maleko89

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Yes, Keihin stamps represent the hole size. So a 150 main jet would be 1.5 mm.

Mikuni is based on flow rate. So a 150 main jet would get 150 cc/min of fuel at wide open throttle.

Mark
 

maleko89

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Obviously you can't swap Keihin and Mikuni jets but Dynojet and Mikuni you can. Here's a comparison chart. Thanks to lvlhead Vmax.

1630251805704.png
 

Parminio

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Yes, Keihin stamps represent the hole size. So a 150 main jet would be 1.5 mm.

Mikuni is based on flow rate. So a 150 main jet would get 150 cc/min of fuel at wide open throttle.

Mark
You learn something new every day. I didn't know that. Thanks.
 

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