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Engine feels tight after full throttle for extended time. Top speed reduced. Normal?

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I have a 2015 cr f 250I.  Stock front tire, Shinto golden boy rear tire.  14-45 sprocket combo, tire pressure at 24 psi, air box mods and vents done, ejk fuel tuner with settings at 2, 2.5, 4.5, 5, 6, 5.5. Stock exhaust with baffle removed.  I have not disconnected the pair valve or the evap cannister, that is still stock.        I went for a 45 mile ride at wide open throttle for the whole ride with the exception of two small towns where the speed limit was low.  The temperature was 70 degrees and no wind.

I normally can get the indicated speed to be 83 mph.  But today the indicated speed would not go beyond 78 mph.  

The motor felt tight and sluggish when accelerating.  After a short 20 minute stop, the bike was fine and seemed to be running cooler.  No more signs of sluggish acceleration.   Has anyone else ever experienced this?  I know the crf250I is not hard to ride wide open on long straigtaways when it's max speed is approximately 70-75 mph.


Any thoughts?  I originally thought valves, but when the bike cooled a little bit, it was fine.  Could the pair valve contribute to this?  I have not removed the evap can or pair valve.

Thanks in advance

Edited by bskicrash1
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Try running 3,3,6, on the first three settings and see if that improves things...you might be running a bit lean seeing as you've done the airbox mods

Edit...my Pair valve is still hooked up but the Evap can is gone

Edited by Neilly
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