250-500cc Can't pull 5th gear

Hey guys newbie to the cafe. Hopefully someone can help out. '00 wr250, just put in new reeds and changed from 410 main to 400, and went from a 30 pilot to 35. Don't have all the other specs off hand but these are the only changes. This was recommended by a number of people at TT and bike shops. Bike pulls find from top to bottom 1st to 3rd gear. 4th seems good at first but then flatens out early and I can barely pull 5th gear at all?? Any thoughts??

Thanks

i used to own one of those .same year/model.i put a vforce and a 51 t rear sprocket on it.then it would pull better in fifth.probably could use porting.dan

That model has the wide ratio box, with perfect jetting and correct powervalve operation and stock 13 48 gearing the jump from 4th to 5th is a big one and if your on the pipe uphill you might have trouble getting back on it. 13 51 is much nicer to ride and still tops out higher than the new ones. Tuning for more midrange really helps too