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View Full Version : Getting the right main jet


sprtrx300ex
10-20-2003, 06:07 PM
How do i know when i have the right size main jet?
ReconRider25
10-20-2003, 07:06 PM
check the sparkplugplug. its gotta be like a tanish brown color
sprtrx300ex
10-20-2003, 07:31 PM
Do I just need to go up untill it boggs then go down a size or two untill it stops?
sprtrx300ex
10-21-2003, 04:53 PM
bump
10-21-2003, 05:15 PM
i find mine by doing this...when i rev it up to the top...if it kinda bogs...im too high...if it sputters or feals like i dont have enough power...i am too low...but thats also because i have a lot of main jets :D
sprtrx300ex
10-21-2003, 05:20 PM
What should i start with. I have the Dj160 in there now.
10-21-2003, 05:23 PM
no clue...i dont fool with those dyno jets...i always run the keihn ones...but how does it run with the 165 dj?
sprtrx300ex
10-26-2003, 06:30 AM
It seems to run as good as 1 60.
10-26-2003, 08:32 AM
i always try to cram as much gas in as i can before i start losing performance...then i go down 1-3 jet sizes...this is usually correct...but if it isnt...i always check my spark plug just in case :D
stupid driver
10-27-2003, 06:32 AM
theere is a very accurate method that i use, and it has always given me great results. What you do, is find a long straight and get into a high gear run( like a plug chop run) Now, instead of killin it, when you get it wide open, let off of the throttle a tiny bit.( about 7/8 throttle or so) If it runs better than when it was wide open, go down on the main and try again. If it was sputtering at WOT and sputters worse at 7/8, go up on the main and try again.

This method has worked for me great. I wish i had learned sooner.