I just did a complete engine rebuild on my 250. New wiseco crankshaft assembly, crank bearings and seals, new wiseco pro lite piston kit, a newly replated cylinder (from an 03 YZ250), and new boyesen dual stage reeds (installed on the stock reed cage). Here's the deal: Last Sunday I rode the bike for the first time since the rebuild and it seems like the bike doesn't want to rev out on top, tons of bottom but considerably less top end then before the rebuild. At first I thought the jetting could be too rich with the new reeds so I put in the smallest main that I had at the time and dropped the needle one clip position. That didn't seem to help very much. Since that didn't help I figured my powervalves were sticking. Side Note: When I was putting the top end together I had to stone out some high spots on the profile in the cylinder for the main center powervalve in order to get the main powervalve to seat all the way closed, after that the powervalves moved freely. Yesterday I removed the pipe so I could get to the powervalve linkage and see if the powervalves were somehow sticking and they weren't. The powervalves moved very smoothly with no sticking. I then decided to do a compression test and it read 240 PSI, which I think is pretty high and I was wondering if this compression could be killing my topend overrev. I was only running 91 octane premium unleaded also. Another question I have is it possible that I don't have enough clearance for the powervalves (in the spots that I stoned) that when cold they are free and when run the expansion of the materials could cause some sticking of the powervalves? Also it seemed that on sunday the more I rode the bike the less I ran into the brick wall feeling of no topend overrev, but it still happened. Please let me know your thoughts on this.
