Hi,

As you know, my NS/RGV project bike came to a sticky end....

For some reason (I probably need my head testing!) I am considering even sillier modifications to resurrect the thing.

It involves putting different barrels on the NS crankcases, so I need spacer adaptor plates making, and possibly welding onto the crankcases.

If this comes off it will be really good.

Just wondered if anyone on this forum has undertaken similar work.....

Mat.

Not me! Matt is your most likely candidate...
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S'funny you should say that as I have an NS400 bottom end sitting in the shed gathering dust with a view to doing something with it.

The owner of the engine just turned up with it and said "see what you can do". He even threw another crank in the box and two sets of carbs.

I've looked at making it bigger using modified NSR150 cylinders. Absolutely no where near being even a bad fit! And on top of that it's only a 2mm increase so would give about 415cc. Not enough.

Paul gave me a b llocking for even thinking of such a ridiculous thing, and said that it HAS to be over 500cc or there's no point!

Oh well, back to the old drawing board.

Yamaha TZM150 cylinders are 61mm, so that would give us about 444cc, which is getting closer.

The crank looks like it was made just before the invention of the wheel, but I think it could be stroked. Let's say we could stroke it 5mm (possible?...maybe), we would get about 488cc. Still not at the magic number.

Anyway, I could waffle on but it won't get the job done. If it was easy then everybody would have a massively oversize NS400.

If it's any consolation, I bored the carbs out

Matt@TYGA wrote:
If it's any consolation, I bored the carbs out

Well, make sure you rebuild mine before the NS400 ones, eh?!
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Lot of work messing with an NS crank.
Nothing available to re-build, but i guess if you're putting stroked rods in, seals and bearings are the least of your worries?

TZR 3XV rods fit a treat as a stock substitute.
Makes you wonder about the barrels?

As Sheppherd does a 500 overbore, the real benefit is in modern barrels I guess?
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CALL me stupid....and im sure someone will but what about MotoX Barrels can they not be used, CR250? or are they just to diffrent or to big,

EVIL a NSR250 with 2 CR250 barrels, LOL NSR500 anyone? you can tell im not technical HUH!

Hi all,

One of the problem with stroking the NS crank is space for the big end, I noticed looking at the NSR250 engine when I stripped it that the NSR has a groove machined (or cast) round the inside of the crankcase to allow a 54mm stroke. I am considering if that will be possible on the NS crankcases.

as for motocross barrels CR250 - in fact most 250 mx bikes have a 72mm stroke - no chance of getting that out of the NS!

CR125 barrels are a possibility, there is one year of barrel that will fit straight on once the reed cage is cut down on the rear barrel

Matt - please let me know if you want to sell the NS400r crank or bottom end... cash waiting - I need one for 'experimenting with' to see if a stroke increase could be done.

Cheers, Mat.

rc46 wrote:CALL me stupid....and im sure someone will but what about MotoX Barrels can they not be used, CR250? or are they just to diffrent or to big,

EVIL a NSR250 with 2 CR250 barrels, LOL NSR500 anyone? you can tell im not technical HUH!

been done mate have a read here : http://www.dreamgate.ne.jp/nsr/Project%20NSR/NSR500/500_part3maim.html
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