H all,

I bought an MC21 last summer and have just about finished a bit of a tidy up of it (bit of paint and a good clean really). The engine was recently rebuilt and sounds and runs fine, so i left it.

The airbox has a neatly drilled set of holes in top and I've done the wire splices (it looked like they'd been done previously and returned to normal for some reason)

Anyway, just been out for my first blast and it feels quite disappointingly slow. it barely wheelies even if you clutch it (not that that matters really, but it might be a good point of comparison?). I went down a dual carriage way near me and just about got 200kph on a donward incline in top gear. it also feels like it drops out of the powerband a bit on each upchange.

I've also got a 1998 RS250 (Honda) and a big four stroke and these are the 2 bikes and other 4 strokes i've ridden in the last few years. i know you can't compare even the RS to the NSR fairly, but I wonder if they have made the NSR feel slow and all is actually fine?

I had TZR's and RD's back in teh day and they used to feel like misiles, but again, is it just hazy memories?

I'd realy appreciate a few opinions please.

Thanks very much

125mph (200kph) is about right for a derestricted NSR.
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If I have to take the carbs off once more...

raineyuk wrote: it also feels like it drops out of the powerband a bit on each upchange.

What RPM are you changing gear at? With my derestricted (otherwise standard) 21SP, an upchange at 11,000 certainly keeps the engine revs firmly in the powerband.

Also worth checking that your powervalves are properly adjusted. If set-up incorrectly, the power characteristics will be affected. Notes can be found in section http://www.nsr-world.com/tuning/250-tuning/engine/
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Rich
MC21 Track Bike / RS250 NF5 'Spencer', NX5 'Cadalora' & NXA 'Aoyama' / RS500 / Two Brothers Racing RC30

Have you put it on the dyno to get an idea of what it's pushing out ?

Rich,

I'm changing at 11k as well. maybe its just a bit of carburation tuning thats needed then.
I was thinking that I should check teh PV's so I'll have a look at those some time soon.

Neal - Na, not been on the dyno, but maybe i will sometime. I was going to wait incase i get some pipes for it.

Stephen - Thanks mate, at least I know its about right then

Thanks all, much appreciated!

A couple of jet sizes can find 200-300rpm extra with ease.

It can also find seizure but you get bonus points for that depending how long the black line you leave is.

You left a nice long one down to the bridge once didn't you Andy
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If I have to take the carbs off once more...

I left an awesome black line down towards that bridge! It was going like f**k that day too!

I seem to recall we were just heading back to your place to up the jetting a little, but I just couldn't stay off the throttle - it was going so well. It was certainly giving your 300 a hard time that day... and that's even before it was tweaked properly!
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Andy.
NSR-WORLD.COM

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Last edited by Andy on Thu Aug 20, 2009 8:24 pm; edited 1 time in total

If your looking at the carbs, first thing to do is check all the jet sizes / air screw / floats are all at standard (and all is clean). Then you know what platform you are on.

My MC21 desrestricted (no holes in airbox) runs very well on standard carb settings. So just opening up the airbox would not require you to go way too far away from these (providing everything else is in line , usually )
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Rich
MC21 Track Bike / RS250 NF5 'Spencer', NX5 'Cadalora' & NXA 'Aoyama' / RS500 / Two Brothers Racing RC30


Last edited by RichG on Thu Aug 20, 2009 8:25 pm; edited 1 time in total

Everything gave my 300 a hard time.
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If I have to take the carbs off once more...

Except another 300... or any MC28!
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Andy.
NSR-WORLD.COM

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If I have to take the carbs off once more...

You love that picture!
_________________
Andy.
NSR-WORLD.COM

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MC28 bashing again?

oh go on then ,if you insist!!!

I post one little picture of a lemon on wheels....
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If I have to take the carbs off once more...