2001 cr250 loading up while idling and cutting out when getting on it hard

Sharpston_722

Ive got a 2001 cr250 mikuni tmx with stock jetting and the needle in the 2nd clip. 40:1 100 octane with amsoil dominator.  Will crank right up and idle all day long but starts load up (gets super richs) after a bit. Then it will have to be cleared out. When riding the bike. He runs amazing but will load up super bad if putting around. If your riding hard it does good but cuts out like its super rich when you get in the meat of the power.F83BC6EC-B791-488E-9DF0-6804B166CD15.jpeg?VersionId=FTMVDMJleQYaPH9E00RgY

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Chance1216
Profile picture for user Chance1216
Posts
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Joined
4/1/2018
Location
Carson, CA, USA
Chance1216 12/25/2025 10:31pm
12/25/2025 10:31pm

Mikuni

Main jet: 430
Pilot jet: 30
Needle: 6BEH1-75
Needle clip: 2nd position
Air screw: 1.75 turns out

I had to order the needle on eBay. It’s tough to find but, it’s correct. 

The jetting on the Mikuni is finicky with varying temperatures and, elevations.  I did purchase a  Keihin Air Striker from a 2000 CR 250 for comparison. I felt it worked better with varying elevations of some poker runs I did. Also, be sure to check your reeds. 

Keihin 

Main jet: 175
Pilot Jet: 45
Needle: stock 
Needle clip: 3rd position
Air screw: 1.5 turns out


 

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