Update on my 250R

[Blown 331]

Well I needed an engine for my 85 250R since my piston shattered and broke both of my crank cases. I found a deal on an 87 TRX motor. I accidently broke the water outlet on top of the head so I swapped my old head on it and noticed the piston was a bit loose. I ran it for awhile then I ordered a piston for an 87 250R. When the piston came I pulled it apart and the piston had 3 huge cracks. They went from the bottom of the skirt almost all the way to the top and you could see one spot where the skirt was hitting the crank shaft, this one was about to go! So I got my 1987 piston and lined up the wrist pin on the piston that just came out the top of the new piston was 5mm lower than the old one! Yep, I have an 85/86 motor. I bought it on ebay so I wasn't sure I could send the old one back but I contacted the seller and he said no problem. Lucky there.
I also changed the the clutch cover and clutch basket. My cover was welded, leaked, and the bolt for checking the oil level was stripped. My clutch felt kinda weird, the plates had grooves worn in it. The clutch bearings were also kinda loose and full of blue silicone!
And an update on racing the 450R's. I'm getting very close with just tuning. If my buddy gives me a half second head start he can't pass me until I hit 6th! (the 450's are tough to beat off the line, if we go from a dead stop I get beat all around by a couple bike lengths) We tried several different riders and 2 different 450R's (both have HRC kit and exhaust) and always the same results. I also have better luck starting in second, first is just too low. I have stock gearing and stock tires. I'm thinking go up a tooth on the front. I also have a 175 main and I need to try a 170. Once I have a fresh top end, gearing corrected and lean it out, it should be very close. My mods are Weisco piston, ESR exhaust, Boyesen rad valve, 36mm flat slide, CR head gasket, UNI filter with open air box. Here is a pic, its with a camera phone so it's kinda blurry.

[wanta86r]

sounds like everyhting is starting to work out for you. Im still trying to get my 86 R tuned in perfectly. Good luck with beating those 450's. I have a similiar setup with top end port work from esr, an atc 5 pipe, rad valve, and 38mm airstryker carb. I hope i can give the new 4 strokes a run for there money. I also am running 14- 39 gearing with sidewinder sprockets and chain. The one tooth on the front really spreads the gears out.

[sandrooster]

The rear tires look kinda worn. New rears like turftamers or razrs will help both starting traction and top speed.

Depending on the surface, if you race on loose stuff like sand, using the lightest weight rear wheels may also help.

[Blown 331]

Yeah, the back tire are some baldy's. I had brand new 18" turf tamers on back but they geared me down even more so I put the stockers back on. We race on pavement so traction really isn't a problem.

[86250RZ]

Try the 14 tooth, made a world of diff. to mine. 175 does sound a little fat, try a 165 to 170. Im running a 150 with about the same mods that you discribed. I had a 155 and it was a little to fat but we live to totally diffferent parts of the country so im sure yours will be a little different than mine. I have also run the 450R's at the sand drags, I dont think any had the HRC kit but they did have aftermarket pipes. Who ever got the holeshot ( 250R vs 450R) took the win.