Adapter for bigger carbs to stock airbox for under $7

Zwiser

Member
May 25, 2010
1,510
16
80
Harrisburg,PA
Ok thought I'd make a DIY to convert your stock airbox boot into a bigger one, I am doing this one for a PWK 35 keihin carb so your sizes might be different. So first step go to lowes and in the plumbing section find a 1 1/4 inch nipple thats about 5 inches long

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ok then look for a 2in X 1 1/2in Drain and Trap connector heres what it looks like

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then connect the 1 1/4 in nipple to the air boot like so,

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then connect the drain and trap connector to the nipple coming out of the airboot

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then connect your carb and your done thats how to make a adapter for a little under $7!!!I:I

pm me if your having trouble.
 
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x2, try bolting it on the quad, you need to cut the boot back a bit in most cases, but you're on the right track!
 
DO NOT go that route. Carbs work on a venturi effect, as the air passes over the jet it draws fuel... This requires velocity. In going from a small diameter to a larger diameter you are decreasing that velocity. This will throw your jetting for a loop........
 
A 4 to 6 inch velocity stack with a pod filter that matches the carb diameter will perform better I think your adapter is creative and at higher Rpm would perform well but idle and mid range would suffer
 
ya it is a ok idea, but it seems like it is hinder performance badly with the going from like an inch to 2inch.
like said before, velocity will decrease.
 
a lot of guys cut the boot back and put a piece of pvc pipe in it with a hose clamp then reduce from the pipe to the carb. you want to go from a big opening to a smaller opening or you will mess you velocity all up like phrag said. it will run like chit.
 
whats the right size and would this work, i moved the pipe up into the carb so its past the 2in space kinda hard to explain so heres pics so you can figure it out

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