Blown 331
05-27-2005, 10:37 AM
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.
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.