Hello guys, this is my first post-what a great forum you have here!

I've just purchased a low km (<16K) NSR250R (MC-21). As far as I'm aware its very orignal/totally complete, with the exception of a non-factory paint job.

I want to track ride the bike only with only modest mods. My questions are as follows!:

What mods can I do that are easily reversible and will provide the most benfit?
is the factory oil injection system reliable enough for high performance applications?
Is a steering damper required? (I'll have the triple clamps as close to the top of the fork as possible)
I'm accustomed to swapping out a main jet on a dirt bike in a matter of minutes-can the main jets be quickly swapped out on an NSR at the track?

I'm sure I'll have more questions at a latter date!!

Thank you in advance guys,

Cheers, Frank

1. Install quick release fuel fittings. After experiencing the convenience on my Ducatis, I have installed them on every bike I own. An absolute must since you will be constantly removing the tank to access the carbs.
2. Derestrict the bike.
3. Replace the exhaust--more for weight than power.
4. Sort the suspension. Either respring and refresh the original suspension or upgrade it with new equipment. Have a professional set it up unless you know how.
5. Get your favorite sticky tires.
6. Make sure your brakes are sorted. After 20 years, you probably need to rebuild the calipers and master cylinder with fresh seals, but at the very least install new lines, fresh fluid, and pads. (I like Motul RBF600 fluid and EBC HH pads.)
7. Get lightweight fairings and use quick release fasteners everywhere possible.

I can't answer the steering damper question. I have one, but it's on the lowest setting and I get the feeling it isn't necessary. Then again, I'm 110 kg and haven't used it on the track yet. Plus, you don't know you need one...until you need one.

Welcome, to answer the oustanding questions:

I've punted around Philip Island and Broadford in Victoria with no steering damper and on oil injector with no worries.

As always, any mods that you do, don't forget to adjust your settings, jets and so on.

All sound advice, from nine16.

The wiresplice and an airbox mod will immediately liberate approx 30% more horsepower, taking an average MC21 from 45hp to around 60hp.



The shaft seal on the oil pump can be a weak point, but on the whole, the injector setup is a reliable system. The seal can sometimes unseat, and move down the drive shaft. Cleaning the seal and housing, and a light smear of RTV sealant to bond it in place cures the problem. Keep the secondary oil reservoir fully topped up, and keep an eye on the level, and you will spot any problem before it becomes any real concern. If the seal moves, it drains the 2T into the transmission.

As nxrsr20 says, changing the standard chambers for race chambers can lose you quite a chunk of weight. Stock pipes are good for 65hp or more, in the right conditions, but weigh a ton! They are cheap though, and if you damage one/both in a crash, being double-skinned, they don't dent easily. They are also good for track days at places where noise limits can be an issue.
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NSR-WORLD.COM

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Hello Guys

nine16, nxrsr20, and Andy, thank you for the valuable advice.

My apologies if some of the questions to follow are trivial, but my current two-stroke mount is an '89 Honda CR motocrosser - somewhat different..

-Can I swap the main jets easily or is complete carby removal required? (I would like to swap these out at the track for the best results)
-When you mention "derestrict" the bike are you referring to the wire splice?
-Is an online microfische available that will allow me to order the correct OEM fasteners/screws for my fairings?
-For fear of starting a debate, is there a brand of pipe/silencer combo that really stands out as superior?
-I understand there is a manual that has been translated in part that can be purchased - is this still available?
-Will an aftermarket reed block alter the carby position or does its simply sustitute the standard and thus not affect the air box position?

Thank you again guys for your help. I can see by the responses I have already that many of you are very passionate about these classics-I like it!. I can't wait to ride this bike.

The bike is really very original/complete as I said, it now has new front dics and pads, new tyres, and I've adjusted the pre-load to suit my weight with a static sag of 20mm and 10mm for the front and rear of the bike respectively.

Thanks again guys

Cheers, Frank

You have to remove the airbox to access the carbs. If you go with adjustable needles, you be able to access those from the tops, but getting to the jets from the bottom of the carbs will require removal. It doesn't take a tremendous amount of time, but it will definitely be more work than your 'crosser.

Derestricting for the MC21 is the wiring splice/mod.

Fiche is available on this site. However, most parts are no longer available. If fairing fasteners are, let us know.

Pipes? There are a handful of ones with good reputations and pretty comparable performance. I have Tyga simply because most of the others are more difficult to source. I will say that the welds on my chambers are absolutely pornographic.

nine16, thanks for the advice

I'll have a look at the microfiche, and if some parts are available I will let you know - I intend on subscribing, so I assume that this resource is only available to those that do?

The Tyga pipes certainly look great - are you running these in conjunction with the Tyga mufflers?

Thanks again,

Frank

The parts manual is unavailable at the moment as we are currently working on the structure of the main site, and the way that some of the content will be delivered.

Regarding the TYGA chambers, yes, it's best they are run with the TYGA silencers too.
_________________
Andy.
NSR-WORLD.COM

Please keep all responses to Forum posts on the Forum so that others may benefit.

Please DO NOT PM me for technical advice. My time is precious, and you will probably receive a faster response on the Forum anyway.

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Great Andy, thanks for the useful information

Cheers, Frank