Hi All,

Can anyone tell me whether the adjustable "B" needles are the same length as the stock needles on the MC21?

Separately, has anyone ever heard of a setup with aftermarket chambers (in this case Tyga) in which the bike (otherwise completely stock except for M-Max) ran best with SMALLER than stock (128) main jets? Sounds like a prescription for disaster to my inexperienced eye but a 2-stroke mechanic I talked to suggsted it was quite possible in principle.

thanks,
Jim
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-Jim
'93 MC21

I have an MC18 with tyga pipes and open air box. Im running 124m/j so i wouldnt worry if you go down a few sizes. I beat my head on tehw all for ages try to use what everyone else was working with.
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If I have to take the carbs off once more...

well, that's very good to learn - puts my mind at ease a bit.
Thanks,
Jim
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-Jim
'93 MC21

If you read the jetting part of tuning in this site you will find the answer to your question. "No" they are not the same ! suggest you read it anyway, it is a lot of help.

my mc16 is running race pipes and modded air box with smaller jets with no problems. if any thing i would say its running a little rich. i think its some thing to do with a faster air flow through the carb drawing more fuel from the jet.but don't quote me on that.

Stephen... remember I was telling you about the guy in the States who was jetting small?! Er, yeah... that'll be Jim! ;)

Told ya... if it works, don't worry! :)

Andy.
NSR-WORLD.COM

And the other question, is no I think the adjustable needles should be longer, as they mate with longer emulsion tubes...
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MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball

Thanks guys. FYI, after getting conflicting signals from the bike, I ended up taking the bike to the local 2-stroke guru to get the jetting finalized. $200 and 16 dyno runs later, he came up with 122 mains (felt there was 1-2 more hp to be had by going to 120 or even 118, but heeded my repeated instructions that I cared more about reliability than max horsepower). Ended up with 40 pilots and with stock needles after trying both As and Bs that I had left with him. This is with Tyga chambers, M-Max, and airbox with 8 10mm holes drilled in it, motor otherwise stock setup. He ran this jetting with the airholes taped over and also open - with airbox closed off there was a bit more midrange but top end peaked about 11k - with airholes open, hp peak was more like 12k. Hp was 61-62, which is just fine by me. Sadly, i can't really tell you how the bike feels yet, because 4 miles down the highway, it went on one cylinder and i came home on a tow truck - not related to jetting I don't believe - I seem to have a separate electrical problem that, in retrospect, was likely the source of conflicting signals I was getting from the bike when I was trying to jet it. If interested in helping sort that one, or if you just want to feel better off than me, please see my post on "coils" to follow. Anyway, thanks for the help on this one.
-Jim
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-Jim
'93 MC21


Last edited by Jim on Wed Nov 03, 2004 5:39 am; edited 1 time in total

I ended up running the stock needles and 124m/j and im still rich too. This is like you, with tyga pipes and air box mod. Im sure it will feel loads better once you get the other probs sorted.
_________________
If I have to take the carbs off once more...