Originally posted by James Dean:
Did the #175 main accelerate better to a point where the #170/#165 would maybe rev out better?
You know the feeling when the bike accelerates hard through the gears and then just keeps reving with authority - this feeling is missing with either the 165 and 170. There is no stumbling and it revs, but just not the way the YZ/WR is so famous for. Topspeed may be the same (I lost my speedo at the last enduro), but with the 175 it is there way earlier. To me this is a lean condition.
Last year I was testing main jets with the DVP needle on a long uphill street section, and while the top speed was identical with main jets from 170 to 185, it just took way longer for the 170 to get to the same speed as with the 180 and 185. Acceleration was also much better with the 180+. This is where a dyno run really would help!
This is a 1998 WR, YZ timing, a little head work, YZ base gasket, WP tork valve (yes, it works) and a modified WP e-series s-bend pipe. Altitude is around 250m.