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Main Jets

Spaceman49

CB750 Member
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Houston
I have just rebuilt the Keihin carbs on my 1970 CB-750. I ordered and received rebuild kits. But the main jets I received were 150's. The jets I removed were 120's. Now I am having trouble tuning the carbs. I can get the idle about right. Although a little high at 1100. The engine runs flat until it hit s around 4000 rpm and then it kicks in.

Before I rebuilt the carbs the engine ran great but wouldn't idle.

I live in the Houston and I am thinking that the 150 jets are just too rich for this are. Reading the spec's for the carbs say's that they come with the 120's.
 
150 are way to rich. I dont even use them in motors reaching 1000cc. Put the original ones in...no need to change them if it ran good before.
 
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