Hi everyone,

Has anyone here done a wet to dry clutch conversion on an mc21? Im currently in the process.

Ive replaced the gearbox, with an SE dry clutch version, But when I try to put the clutch on it doesnt seem to mesh with all of the gears.

It seems to get stuck on the helical gear that runs of the crank. are these different for dry and wet clutch versions

thanks in advance for any help

i have read somewhere that the 2 gears are different between the wet and dry clutch .

yes i have just read for a 28 to 21 conversion that thep rimary drive must be changed
( http://www.nsr250.net/forums/viewtopic.php?t=2031&highlight=dry+clutch+conversion )

bugger any suggestions on how to undo the primary drive, apart from take a piston off and jam something in the conrod,
Is it a left hand thread?

The 21 and 28 have different primary ratios, so you can't mix and match the primary gears.

The bolt that holds the primary drive gear on is a normal (right hand) thread.

I use a piece of aluminium to jam the gears. Thanks to the helical cut gears it's not easy just grind up an old gear to lock them.

Thanks matt worked a treat,

so now i have the bolt undone, and have been trying to pry the gear off the spline with a screwdriver... and its not happening, whats the recommended practice here.

Just a quick note. You shouldn't use a bar through the con rod to undo anything really or do up. Its very easy to un-true the cranks. Twisting a crank like the NSR's (pressed up) will do it no good at all.

Thats what I've found anyway. But Ive been called names for some of the things I've found so lash into me if you wish!
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If I have to take the carbs off once more...

StephenRC45 wrote:Just a quick note. You shouldn't use a bar through the con rod to undo anything really or do up. Its very easy to un-true the cranks. Twisting a crank like the NSR's (pressed up) will do it no good at all.

Thats what I've found anyway. But Ive been called names for some of the things I've found so lash into me if you wish!

YIKES!!! I've used this method on the last few rebuilds/clutch conversions.

http://www.nsr-world.com/workshop/rebuild/rebuild-2.php

What would you suggest Steve??

Whoops yes my recently rebuilt crank does sound a bit rattly. i guess i could have read my workshop manual to find the proper method, but Ive found that involves reading.

So any tips on taking off the primary drive, Use a bearing puller?

I use the Mr Matt way and have either the Honda tool (which is a couple of teeth of a gear on a pin) or a lump of aluminium between the teeth.

The crank primary gear should just pull off but if not a thin two legged puller does the job.
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If I have to take the carbs off once more...

OK, OK, OK... one day I will get round to doing some more updates!

It's not the perfect way to do it, but nothing should really be that tight when you come to undo it! It was good enough for Haynes in their day, and I grew up on a diet of their workshop manuals and Hammerite reconditioning paint, and it hasn't done me any hurr... any hurr... any harm!!
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Andy.
NSR-WORLD.COM

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I guess my second crank is stuffed if that's the case

I wonder what will happen to the third if I bother

Recently was rebuilding Paul's 250 and while reassembling I needed to lock the primary. Well, I'll usually do rebuilds at my house, but in this case I was doing it in the factory. Hunted around for a bit of aluminium to lock up the gears but all I had was a few bits of scrap 6061 T6. I can now tell you that this is not good. 6063 is much better, and a lot cheaper.

Just some useless info for y'all

bandit_7 wrote:
I guess my second crank is stuffed if that's the case

I wonder what will happen to the third if I bother

After several sets of rings and a few sets of pistons, which is only to be expected if it's maintained properly, that motor I used for the rebuild section is still going strong over 10 years on.
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Andy.
NSR-WORLD.COM

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Andy wrote:
After several sets of rings and a few sets of pistons, which is only to be expected if it's maintained properly, that motor I used for the rebuild section is still going strong over 10 years on.

I'm not too sure about the condition of the motor you refer to, but the motor I did it to looks like it was never dismantled to crank removal stage in 20 years.

Will this make any difference?

It's impossible to say what condition a crank is in after 10mins, let alone 20 years, especially if you have no idea of it's service history.

A crank when I was racing would be in the race bike for 1000kms, then go in my street bike.

Granty's crank has lasted 10 years because he's alway in Thailand forcing me to get drunk, so never actually rides it