I have recently had my MC21 rebuilt. Just back to std. It has std chambers (you try and find anything decent in australia) with some custom mufflers (stainless 1-1/8 ID, 2-1/4 OD, 9" long)

I havn't done the wire splice de-restriction yet. But i want to mod the air box lid by cutting some holes in the top of it.

It has been mentioned in other threads that the main jets should be swapped for a larger item. Is this an easy job ? Do i have to take the carbs off, or just dissassemble them on the bike ? Should i change the needle position as well ?
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Winning isn't everything, but loosing isn't anything

IN order to change the mains, you will need to remove the carbs. Not that hard of a job really.

With a modified airbox, you will probably want to go up on the mains (match the added air intake so your not running too lean). As for the needles, that all depends on what the bike feels like at 1/4 and 1/2 throttle.
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Charles Gallant

I'm not totally sure on the NSR, but on other bikes we have just added washers under the needles. The HRC recommended needles are suppose to be the same profile as the stock needles, except with grooves.
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james
Its not how fast you go...Its how you go fast.
MC21 Rothmans
RS250
RC31
CRF250X
748R
Porsche (many)
http://members.rennlist.com/j911brick/rennlist3_002.htm

You can get one 0.5mm washer under the shock needle before it fouls the stock needle retainer so there isnt much adjustment there to be had.

You really need the HRC needle and retainer to do the job justice.
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If I have to take the carbs off once more...

j911brick wrote:I'm not totally sure on the NSR, but on other bikes we have just added washers under the needles. The HRC recommended needles are suppose to be the same profile as the stock needles, except with grooves.

The 'B' HRC needle for the MC21 has a similar profile to stock but not the same and the A and C needles are quite different.
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NSR300R - Why did i ever have a 250...

Then you have the Avgas range of needles plus the 10 F3 ones!
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If I have to take the carbs off once more...

Thanks for the info guys. Unfortunate for me that getting stuff over here is difficult.
Is the main jet a NSR specific jet, or is it more of a universal item ?
I can't just 'go to a honda dealer' as they dont want know about an NSR as they are an import
You really need to know someone who knows someone to get a hold of anything good, unless you order it from overseas, like from you guys
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Winning isn't everything, but loosing isn't anything

Keihin main jets are just Keihin main jets, used by a huge range of Keihin carbs.

Just ask you dealer for 99101-393-XXX0. The XXX being the main jet you need, such as a #150 main jet would be 99101-393-1500. There are other numbers which are specific to a particular bike, but I've never found a problem just giving the above number and they'll find a cross reference if there is one.

Hopefully this will help others to find jets, and stop them buying all mine

Negative sellling, like it!
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MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball

I just wanna go and sit on the beach!

Thing is, my main jets are like family. there's nothing worse than knowing you can make a horse or stop a seizure, only to reach into the jet box and there's just a big empty space where there should be a jet

I wish people needed #128 mains as I'm overflowing with them!

Excellent. Thanks again
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Winning isn't everything, but loosing isn't anything

Matt@TYGA wrote:I just wanna go and sit on the beach!


I wish people needed #128 mains as I'm overflowing with them!

So where's your drill and stamp kit huh?
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MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball