Modified XR650L Bogging Issue

Hello all,

I recently put back together my 2008 XR650L with a list of the following modifications done to the engine:

Smog Delete Kit

FMF Q4 Silencer

Opened up Airbox

Uni-Air Filter

Lip removed from inside headers at engine flange

FCR Carb

Wiseco 10.5:1 102.41 mm bore piston (so now it's a 675cc pig)

Hotcams stage 1 camshaft

Head Ported and Polished by Trinity Racing along with 3 angle valve job

Oil Cooler from GS Mark

The FCR carburetor has a 178 main, 45 pilot with the screw turned out 1 3/4 turns, 45 slow jet at 500 feet ambient temp high 60's. The bike runs great and cool, since I'm able to monitor temps with my Trail Tech Voyager GPS, but bogs in very distinct situations. If I really wind it out in 5th gear, the engine will temporarily cut out. Also, if I'm at full throttle for a few seconds and start to get up high in the RPM's, chop the throttle and try to get right back into it the bike bogs for a couple seconds before picking back up. Once again the bike runs great and can pull the front wheel in 3rd, but it has these little mystery issues. I'm not sure if the spark is getting blown out or what the deal is, so I figured I'd post my story here to see if anyone has any ideas behind the cause of this bog. Any input is appreciated.


If dot-com doesnt solve it Toyoko-mods will go all through the carb and bench test it for 180 bucks.

I just installed an FC on mine and followed dot-coms info to set it up. Mine has a tiny little blup at idle if I whack it b ut only after it idles for 15+ seconds. Just a tiny blurp. If Im using the throttle it wont do it. I also noticed a distinct shut off if I back off the throttle (20%) after running flat out in 5th for several seconds. Its like someone cut the fuel and its freaky.

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