Thread: 155 main jet?
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Old 03-28-2017, 08:10 AM   #2
rks   rks is offline
 
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Join Date: Dec 2013
Location: Western New York
Posts: 454
You certainly don't need a jet anywhere near that size to feed a 150cc scooter. You must have some major air leaks between the carb and the head.

I run a K&N cone filter on my scooter.......stock exhaust.....and a 115 main jet is just right. I don't care what you have done to your exhaust....it will not require as big of an increase in jet size as you have already made.

I have a two cylinder motorcycle, with a separate 32mm Keihin Carb for each of it's 375cc cylinders. Came with conservative 125 mains.....I have upped them to 135.

My 400cc Yamaha ATV has a Mikuni 33mm carb.....it has a 112.5 Mikuni main jet, which is equal to a 128 main in a CVK, or Keihin carb.

Better check that manifold and such.
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