Got a '93 F2 with a D&D slip on and a K&N filter. Had a kind of a burble in the low/mid range, almost like a flat spot, but not quite, more of just an odd sound. Starts about 3000~3500, and clears up by about 4000~4500. I guess it really is a flat spot, because if you just twist the throttle a little bit and hold it there, as it comes above 4000, it accelerates harder all on it's own. It had 130 main jets in it, and still did it even with the needles raised all the way to the last step, and yet the plugs were still reading a little bit lean. A friend drilled the mains to the equivalent of 138s, now it won't turn over 11,000 without missfiring badly. Did a 2 full throttle runs through 1st and 2nd gear, killed it clean, and the plugs are almost sooty dark dark gray. Now the question, anybody got a recommendation for what main jet size to order? I'm thinkin either 132s or 134s..... TIA, Rick

138 must have been wayyy too much fuel for her. I would go with 132 and if the problem with running lean still exist then have your friend drill those out to 134's if he can.

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I don't think we'll be drillin any more jets, I've done it myself, on my own outboard motors, but I would rather just buy the right ones. He owns a bike shop, and wouldn't tell me the actual size he drilled, just that it was the "equivalent to a 138". I think he had some kinda chart, but I didn't get to see it. I know NOW that I shoulda been tuning for (reading the plugs at) WOT first, so I think it will go smoother from here out.

"I" would go with 132's. going from a 130 to 132 is a much bigger step than you think. You want it alittle on the leaner side anyways. I would take the needle back some too!

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1998 CBR F3 R.I.P.
2004 zx6r R.I.P.

It's been raining here for 3 frickin days, now it's sunny again, and I'm jonesin for some ridin. Just picked up a set of 134s a dyno shop here in town had in stock, (didn't have any 132s), guess I'll try them. Just gotta decide where I'm gonna set the jet needles at. The mid-range runs pretty good right now with the "138s" in it, but feels a little fat. Since you guys say 132s I guess I'll try em at the 2nd groove down and see how that does. Thanks,

No prblem brotha......let us know how it goes!!

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1998 CBR F3 R.I.P.
2004 zx6r R.I.P.

Well, I swapped out the main jets last night. If those 130s were actually drilled out to "138s", 138s are frickin huge compared to 134s. I'm wondering if they hadn't been drilled already. Seeing the difference, I decided to raise the needles all the way up to begin with. The good news is that it pulled harder than it ever has, right up past 13,000, yanking the front tire going into 2nd gear, repeatedly, (never really did that before). But now the midrange is worse than ever, , but I'm not sure if it's rich or lean yet, gonna read the plugs again after riding it home and back to work. I'm confident I'm headed in the right direction, just need to do some more riding and plug reading.

OK, last night, I dropped the jet needles to the middle clip and adjusted the pilot screws about 3 times, and it's running SWEET, no more mid range burble or flat spot, and it FEELS as if I picked up some top end power as well, guess i'll know for sure next trip to the track, probably next Friday or Saturday night. Thanks guys,