woodruff keys

[Jeram]

Hi Guys

just before I go putting my clutch side of engine back together I though Id query you guys on crm woodruff keys.

I wouldnt call mine 'loose' but you can easily remove them and insert by hand... which is a first for me.

has anyone else found this on a CRM or are mine worn and need replacing???

[john7780]

i would say if theyre loose and have play when fitted then replace them but if theyre only loose enough to slot them in with no sideways play then theyre fine mate they are cheap enough anyway

[Jeram]

yeah no sideways movement from what I can tell... they just slide in and out really easy.

was a bit freaky for me because other bikes including my ktm380 and other friends ktms have very very tight woodruff keys that are pains in the arses to remove!

Iv gota buy new bushes and bearings for my linkage, and a new clutch nut and counter balancer nut so Id might aswell get new woodruff keys if they are cheap as chips

[karlloss]

Jeram, just finished rebuilding my CRM Mk2 with new balance shaft, woodruff key same as yours, came out easly, almost loose, but once gear on the shaft no side-ways play at all. Prior to my current job I worked as a mechanic for ten years, and from my experience woodruff keys can vary from needing to be prised out with chisels to falling out as the gear is removed from the shaft, in fact I'd argue the keys that fall out (providing no play when all tighten up) are the better ones, as it saves damging the shaft to extract them.

[karlloss]

PS, if the key is worn you will see the wear on the sides of the key.

[john7780]

got it in one karlioss, ive been a mech for 18 and very much agree

[Jeram]

great replies fellas!

thanks

[fallenmikethebike]

The purpose of the key is NOT to hold the flywheel on, this task is taken care of by the tapered conical end to the shaft.
It's always a good idea when you have the magneto of to re-dress the magneto to the shaft using some, coarse, then fine, valve grinding paste, remembering to clean it all off thoroughly.
The key, and key-way merely ensure correct timing, though of course being CRMs, there's no adjustment for any manufacturing errors.
Mike

[Jeram]

yes, the woodruff keys are far too small to support any sort of significant load :)

[karlloss]

Fallen is correct. The key is purely a location device, some shafts/gears/pulleys use pins or dowels. For the balance shaft the settings need to be as per factory. However if you want to change the ignition timing off-set woodruff keys can be used. These keys basically have a step in them to either retard or advance the timing. Off-set keys were popular in the car world for setting the timing of camshaft gears. You will only need a millimeter or less to make a few degrees change to the timing, due to the radius of the flywheel, a small change on the shaft will produce a larger change on the circumference of the flywheel. Obviously the easiest way is to move the pick-up, but not sure if this can be done on the CRM. Might be worth looking into to change/set your ignition timing after all the mods.

[Jeram]

Thanks fellas, thats some good info.

and because the thread has a pretty self explaining tittle it will be easy for people to search it in the future :)