hello from germany! i am new in this forum and a new owner of an 96er SE modell MC28! i try to rebuilt this bike because fairing is in an desolate condition and i like to give him a new optic!
i work on 2strokes many years! first RGV250,RS250 aprilia and then RS250R from honda!
the NSR250 that i bought now, has 36mm carbs mounted!! this is not standart,i think! can someone tell me from what modell they are?
cheers,michael
http://foto.arcor-online.net/palb/alben/27/3107527/1024_6639396538383538.jpg
http://foto.arcor-online.net/palb/alben/27/3107527/1024_3833396566376263.jpg

Those are standard TB10A MC28 carbs. Definately NOT 36mm. They are not bored straight from the factory, the outlet side is actually a tad larger than the diameter at the slide.
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Paul Herr
'88 FZR4/GSXR/YZF Frankenbike
MY BIKE PICS

thanks! i have check it and you are right! outlet is nearly 36mm but innerdiameter at the slider is 32mm!
it looks like their is an HRC jetkit mounted! needle with clips!
in my other garage are the spares from this bike and also an secong carb set! did the SP modell have larger carbs?
michael

NSR250 Carburettor Setting Data

All MC28 models use 32mm carbs. They type differs between some years and/or models, but all are the same size.
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Andy.
NSR-WORLD.COM

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did you know someone who can bore them a bit larger??means 34-35 mm!! michael

Any good engineering company should be able to bore the carbs, but I seem to recall the MC28 carbs will only go to about 33.5mm maximum before you break through the casing.

MC28 carbs are easier to bore than MC21, as the venturi are round.

You'd be much better off using RS PJ38's or PWK's if you want to go for big carbs. The inlet manifolds are hard to source though.
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Andy.
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yes,but problem is the orginal airbox will not fit the 38mm carbs!!
why did no one built this? i think many people try to get a airbox for 38er carbs. i can not use them without here on street! it to loud!
michael

I think your limiting factor is going to be the PGM-IV, not the size of the carbs!
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Andy.
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please explain me this with the PGM-V!! i have the HRC card for it! is the power from this ignition limited? i know it cam be changed to an PGM-3 ignition so it is no real problem if this is better!

but an airbox is better for both ignitions ,i think! michael

Pay no attention to Andy's '28 witch hunt, on a normal 250 there's little to choose betwen a spliced PGMIII and an 030 carded PGMIV. Both will make low 60's bhp, the problem is on a '28 you need the 030 card, on a '21 you need a soldering iron. Actually you also need the soldering iron on the '28 too.
But as you have to HRC card already this is a moot point.
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ok,i have an 030 card for my mc28 ignition! but sorry,my english is not so good! what did you mean with:soldering iron

mfg michael

Lötkolben

this mite be better nsr250 tuning page

ah,you mean the parts with cutting some wire and fit them on some others? michael

To get 60bhp from an NSR250 mc21 you need to do both wire splices (the soldering iron), drill two holes in the airbox and rejet, maybe an hours work and a fiver for jets.

To get 60 bhp from an NSR250mc28 you need an HRC030 card, then do the wiresplice to allow the card to work (soldering iron), drill two holes in the airbox, either remove the exhaust restriction or get some pipes and rejet, maybe a days work and not that cheap, but then again you've paid a grand more for the bike for no good reason other than the pose and you'll get it back if you sell.

Before any '21 owners get cocky to get 60 bhp from an early NSR250mc18 r2j you need to pull a bullet connector apart near the PGM, maybe 10 mins work, Wayne reckons you might reach it with the seat unit in place, maybe 30 seconds then.
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