WTF!!! By knottidedown (Read 965 times)

[cyborg]

it's not moving enough air,,,the filter should be at least twice the size of the one you bought

[Guitarman]

Leave the cover off. You're strangulating the motor.

[Alleyoop]

Use that filter BUT WITHOUT THE BLUE COVER, then find the right main jet that will match the amount of air from the filter.
Start with the 115 main jet and work your way down from there, 115 so you do not run lean.
Alleyoop

[richardv]

That's why the original air box is so big.

[beebo]

I think you guys are right about the filter being too small. That little filter might work alright on a little 49cc motor, but it is way too small for a 150cc. It looks to me like Alleys' filter has 4 or 5x the filter area or more.

Were you trying to mount that little filter directly to the bell of the carb? These CV carbs seem to be real sensitive to the quality of the air flowing into the mouth of the carb. They seem to need at least a couple of inches of straight tubing between the filter and the carb, so the airflow can "straighten out" and become more laminar before entering the carb. Alley, it looks like you have around 4 inches or so of intake tube between your filter and carb. That is about what I have been using on mine. My filter is a little bigger yet, but mine ran like sh#t until I put a short piece of tubing in between. I could really tell the difference when it fell off during my experimenting-it really lost that seat-of-the-pants feel of power, and I would have to pull over and put it back on. I rigged up a bracket similar to Alley's and it has stayed on ever since.

I think I wound up going up 2 jet sizes and as long as I don't dog it too much, I get at least as good mpg, maybe better than before.