So I got my Keihin 34mm PJ on and went out to the track last night to try and get it dialed in. My motor is stock except for a DMC pipe and Vforce reeds, and now the Keihin carb. I plan on a 3mm stroker and some port work in the near future. Here's what I learned so far.
1. Everything you've heard about these carbs being tough to tune to idle properly is true. However, if it won't idle and the air screw and idle adjustment don't seem to have any effect, your pilot is likely too big. When I got my carb, it had a #60 pilot in it. It wouldn't run below 1/4 throttle! I settled on a #42 after lots of trial and error. The air screw is still 2 turns out, so I may go down to a #40. But as is, it will hold a semi-decent idle and has good off-idle throttle response.
2. On the advice of blasterfreek, I went with a #145 main to start out. It ran OK, and because I was at the track, there wasn't anywhere to do an extended WOT run to check the plug. Just to be safe, I changed to a #148. It hit harder and pulled higher, and ran a bit cooler too, so I stuck with that.
3. After changing to the #148, it ran a bit gurgly about 1/4 to 1/2 throttle and low to mid RPM's. I dropped the needle one clip and ZING! Nailed it. Runs clean throughout now.
Hope this helps some of you, I know there has been some discussions on this carb. I like it. It's much easier to disassemble than the stock Mikuni, and they can be had very cheap.
1. Everything you've heard about these carbs being tough to tune to idle properly is true. However, if it won't idle and the air screw and idle adjustment don't seem to have any effect, your pilot is likely too big. When I got my carb, it had a #60 pilot in it. It wouldn't run below 1/4 throttle! I settled on a #42 after lots of trial and error. The air screw is still 2 turns out, so I may go down to a #40. But as is, it will hold a semi-decent idle and has good off-idle throttle response.
2. On the advice of blasterfreek, I went with a #145 main to start out. It ran OK, and because I was at the track, there wasn't anywhere to do an extended WOT run to check the plug. Just to be safe, I changed to a #148. It hit harder and pulled higher, and ran a bit cooler too, so I stuck with that.
3. After changing to the #148, it ran a bit gurgly about 1/4 to 1/2 throttle and low to mid RPM's. I dropped the needle one clip and ZING! Nailed it. Runs clean throughout now.
Hope this helps some of you, I know there has been some discussions on this carb. I like it. It's much easier to disassemble than the stock Mikuni, and they can be had very cheap.
