Loss of Top End with '03 YZ cam?

When I had WR timing, my top end was about 82 or so. When I switched over to YZ timing, the bike was much quicker, but the top end dropped off. Maybe top speed of 72 with YZ timing.

Now I have the '03 YZ cam in, and the top speed reached this weekend was about 67-68. Are these numbers common?

Maybe my jetting is now rich with the warmer weather, but my bike seems to be falling flat on the top end. Will lean out the main circuit to check that. Anybody else think these numbers are OK?

My gearing has been 14/51 the entire time, and has not changed.

Thanks for your thoughts on the matter...

Have you got the Powernow or done the James now mod?? i lost some top end when i did the James now.

I did not notice anything substantial off the top with my JamesNOW plate, serial number 000002. :)

But, I just switched from a 160 to a 155 main jet (I love having the office located 5 minutes from home!) and the bike is alive! Don't know where top speed will be, but the bike is running much crisper. I think I was too rich in the main circuit.

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