Ok, new guy here, but I used to be here a long time ago (I used to be corndog67, but that seems to have disappeared, someone hacked my msn account, it's not like I'm in the witless protection program or anything), I've had older XR's, CR's, a YZ450F and probably 35-40 other bikes over the last 39 years of riding. So this isn't my first rodeo. I just bought a 93 XR650L, big fin head, fresh valve job, HRC cam, ported by XR's Only, JE 675cc piston at 10.5:1, Carillo Rod, all freshened up, stock carb and stock pipe, but it came with an XR's Only pipe that the previous owner deemed way too loud for his tastes. The guy did a really nice job on this bike, very, very well detailed, and I haven't found anthing hinky at all about it. It runs cleanly with the stock pipe/carb setup, other than a little bit of popping on decel, but the issue I have is that after the initial big thump through the middle of the rpm range (no tach, so it's a guess where it's running, but it isn't wound tight at all), it seems to run out of beans a little early. Years ago, my buddy had a Muzzy built XR600 (XR628), that I remember had a load more top end than this bike. Would I be correct in assuming that the stock carburetor and pipe are choking this sled down? I believe the valve sizes are stock. I read another thread about using an FCR off of a CRF450R on there, would that wake this beast up? Along with the XR's Only pipe? One other question. It has a 19in. wheel on the front right now, with a big rotor kit, along with an extra set of dirt wheels (21 and 18), and a 17 on the rear for the street set up. I was considering putting a 19 in dirttrack tire on the front, like an old DTII Goodyear or Pirelli MT53, or whatever they are currently using out there right now. Or would it be a better idea to lace up a 17 and just use supermoto tires or full street tires? Any opinions or advice would be appreciated.