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Discussion Starter · #1 ·
I know this was covered in the past but I can't find the posts. 95 XCR 600 that bogs out on warm days = above 20 degrees. Plugs are light brown so I'm assuming that means the main jets are right size but the pilot jets are rich. I took the diffuser plate out of the air cleaner and it ran better. What size pilot jets should I go to?
If you "roll" into the throttle coming out of corners it doesn't bog, cruises fine at 40 MPH and a WOT, bogs bad around 50 - 60 MPH.

Sled background - new belt, rebuilt secondary clutch, rebuilt engine with 2400 miles on it, 3900 mi. on chassis, new carb boots, new fuel pump, new plugs (tried BR8's,9's, and RN2C's).
 

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In my 95 XCR 600, I went to smaller nozzles (needle jets) to get it to perform better. There were some of the 95s that were actually a bit lean with stock pilots also. You have answered some of your own questions with colder vs. warmer temps and removing some of the restrictions from the air box. If you are interested in smaller nozzles, I have 3 Q-0 & 3 P-8 nozzles to use in place of the factory Q-2s. Q-0 is 1 size leaner, P-8 is 2 sizes leaner. You can try moving your needle E-clips up or down 1 slot at a time to see how it responds. Always check plugs and piston wash and take small steps when tuning.
 

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Discussion Starter · #3 ·
The biggest mystery to me is, why did it run great for the first winter then start bogging half way through the second winter - after rebuild? It has 120 PSI compression in all cylinders also?
 
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