02 RM 125 Running Rough 1/2 throttle

[robwbright]

Hi guys:

I've been experimenting with gearing changes for different tracks I race.

I recently tried 11/52 on my 02 RM 125. Very short powerband, but REALLY EASY to keep on the pipe. I think it will work well for a really tight track . . . However . . .

My bro and I were riding out to the local ash pits behind power plant and I was running in 6th gear about 1/2 throttle.

The RM was running really rough under these conditions. It felt like I was blipping the throttle every 1 to 2 seconds even though I was holding it at 1/2 throttle. It ran fine at 1/4 throttle and fine at 3/4 to full throttle.

The RM ran well at the ash pits - no cutting out in any conditions.

I haven't noticed this issue at all before. The last time I went out to the ash pits I was running 12/49 and the bike seemed fine in 5th or 6th - actually, it was fine in any gear.

I know the gearing has nothing to do with whether or not the motor is running properly, so I'm assuming I haven't ridden at that particular RPM for an extended period of time in a high gear.

Any ideas?

Thanks

Rob

 

[Agie rider 76]

What is your top-end like?
Otherwise, possibly a jetting issue. what mainjet are you on, and what's your needle position? Also, what premix ratio are you using?