A common problem with 4-stroke carburetors is the dreaded bottom end bog. This usually takes place when the throttle is snapped quick from idle and the fuel is not delivered to the cylinder quick enough and the bike cuts out for a split second. The bog can definitely be eliminated or adjusted by re-jetting, but I wanted to try a simple technique using an o-ring. … [Read more...] about How-To: FCR Carburetor O-ring Mod