Well i did a search for this but didnt find something.

Has enyone done a stroke up crankshaft work?

If yes how much and what was the results?

Thanks

The stroke up can be done to every crank no matter construction?

You need to find a conrod that will fit before you can start a project like that ! It can be done .

I don't understand the question - what do you mean by stroke up?
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MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball

is it not a longer conrod ?

I think he means stroking the crank.

Requires either off set grinding the crank pin or removing the pin all together and relocating it to give a lower stroke.
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If I have to take the carbs off once more...

A long stroke two stroke eh?
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MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball

Yes stroking the crank it is...

You relocate the pin holding the rod away from the crank, so you increase the stroke to get more cc's.

The problem is that crank on NSR seems a little snug fit in the cases and the

pin also seems it cant be relocated much out... thats why i ask maybe someone has tryed or something, so as to find out what is waiting me...

I am not afraid about rods you can find lots of them and exactly as you want them.

Never thought of it being done on a two stroke before. Doesn't that monkey around with mean piston speed and stuff? Or make it lower revving?
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MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball

You will gain more torque surely what is needed to keep the bike alive and keep up with bigger bikes...

I will get a second crank to a specialist for this job as to find out what can be done.

"Stroking" 2 strokes is big business here on Banshees when racing the Sand Drags.

Machining the cases is required to clear the crank.

I wouldn't know how much material is available on the NSR cases for clearance.

if your trying to increase CC's would it be easier to go with the tried tyga 300cc kit?

can you get a somewhat reliable extra 50ccs from stroking?

lam.666 wrote:
can you get a somewhat reliable extra 50ccs from stroking?

Can you with a 300 kit?
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There`s no cure for stupidity… but with the endless supply of stupid people around me, I must be close to finding it!

The Lizard tells it like it is!

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Vampire?

A quick 2 minutes with a calculator shows that stroking is a lot of work for not a lot of gain with a 54mm piston. Moving the crank pin 2mm further out (much easier said than done) only increases stroke by 4mm giving 268cc on 54mm pistons.
The bigger the pistons the better (hence use on YPVS with 66/64/68mm pistons) - If you use Tyga 300cc pistons (which I guess are 59mm) then you get 320cc on a 4mm stroke.

Stroking is specialist work, and I only know of 2 places:-
http://www.faliconcranks.com/crank_svc.html charge US$868 to stroke a twin, if they feel it can be done
http://crankworks.com/index.php/motorcycle/motorcycle-services-2 they want US$600, again if they feel it can be done.

These figures assume the crank is amenable to stroking - integral crank pins with forged webs are more difficult to stroke as there is not enough metal to remove in the right places. A top hat bush can be used
http://www.kaila.net/tl125/tl125bigbore.html

You must also include the work for trenching the crankases - the NSR already uses trenched cases. Care must be taken to make sure you dont end up with an expensive crank and then break through the cases when further trenching to make it fit - weld and/or epoxy first before machining. See Norbert's 350 big bore page for details
http://homepage.ntlworld.com/ultimatelccrazy/html/casings%20blow%20ups%20.htm

Other options are available such as smaller crank pins and/or narrower big end needle rollers, but it is all a compromise and diminishing returns springs to mind.

If you are after a modest stroke increase, consider an offset crank pin
http://www.mbdevelopments.co.uk/other/gt1.html
This only works if the crank does not have integral big end pins.

Once you have your stroked crank installed in the cases, you need to space the cylinders to achieve the correct port timing and compression ratio and squish you want/need. This can be achieved with custom base spacer plates and copper head gaskets, but some machining will usually be required, especially if different pistons and rods are being used.
Then there is the associated revised inlet work, jetting, ignition and pipes etc...
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NSRless again...