I was thinking about drilling the 2.5" hole in the airbox that people talk about. If I am running a .160 jet right now with 8 disk in the FMF, how much will I need to jet up to get it close to right with the drilled out box? .165 or .170?

 

Not sure if you're talking about the RCR mods. Cutting the snorkle back and fitting an inlet into it. Also basically just cutting open the panel that holds the black venturis. Sorry if you already know that. Unless you're submerging in water, I've been running the cone K&N with the water repellent Outerwear on the trails and had great luck.

just my 2c
Ken Thompson

 

WHOOOOOOOAAAAAAAAAAAA!!!!!

Do not drill a hole in your 500 cc polaris airbox. You will actually slow the machine down even if you rejet the carburetor . To properly open up the airbox and modify the carb to match the increased airflow it takes several parts for the carburetor that total $110.

This is not the case with other polarises as a general rule. The 400's and the 250's can be modified simply and for minimal cost .

 

Thanks for the help! I thought the airbox kit for $110 was the way to go, so I'll do that.
I understand it comes with a .170 jet. Is that enought for an 8 disk FMF, or do I even need to go up from there?
Also, is this a good top end mod?

 

Rick, what has been your experience drilling holes in the 500 air box?

Why will it slow the machine down?

Thanks.

 

the 500's carb relies on vacume from the airbox to open up the slide,drilling holes in the airbox messes up the vacume which doesnt allow the carb slide to work properly.thats my understandment of it anyway.