KR-1S.co.uk Forum

I have been advised to have newly rebuilt cranks welded for racing use.
Does anyone know exactly where they should be welded ?
Thanks
Ronnie

i think the mean the clutch gear thats mounted on the crank.

Jarno is right, Stan Stevens used to tack weld the press fit drive on the righthand side of the crankshaft.
Not sure if it was actually needed.

Cheers
Bernie

Yeah this is what I've seen done before, but I can see how it prevents any crank twist and or anywhere else you can weld the cranks. Not sure it is worth doing myself, as I've never had this problem. If it seizes, there's going to be the possibility it is going to twist the crank, welded there or not.

did that advice come from banshee/RD guys ?

it's often done to after market cranks for them, as they mostly are cheap. cheaper to buy a new one than to rebuild. and some are so cheap you can question their quality when they make it sound like/advertise it's better to weld them for strength while they probably won't stay trued far half a mile when they are not welded.

Thanks for replies.
Welding seems like last resort
My crank builder here is going to spark erode keyways into journals.
He asked if there was a mark on balance shaft gear to correctly align on crank rebuild?
Ronnie

russell wrote: My crank builder here is going to spark erode keyways into journals.

has he done that beore ? I don't know anything about crank-building, but this might give problems :
- there will be 2 sharp edges, and in edges cracks are more likely to ocur.
- the tension will no longer be even spread arround the circumference of the web, putting even more stress on the sharp edges

I'd might ask for some sort of guarantee that if te webs crack in the edges he replaces them.

russell wrote: He asked if there was a mark on balance shaft gear to correctly align on crank rebuild?
Ronnie

I don't think there is. all the KR crank jigs I've seen on the internet have special devices to keep the gear in the correct position.

Thanks for that, will see him today

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>>> click for more in PDF <<<

because the crankpin/journal is integral with one side of the web on a KR
I would guess is already more rigid than bikes with 3 piece cranks (web - pin - web) where welding is seen as improvement

Some tuners had thought that removing the balance shaft improved horsepower, but it only reduces inertia but increases vibration - in that case probably requiring the pinion gear being tacked into place. On the KR the primary reduction is straight cut to start with so there isn't side the loading force as experienced on cranks with helical cut gears (NSR, RGV etc)

You could see welding as beneficial if the bike is seeing increased or extended high rpm, such as your race bike. (staying true longer)
On the other hand, you will be doing more tear downs and maintenance on a race bike anyway, and refreshing crank bearings and seals would be more a PITA if its all welded up?

http://bdkraceeng.co.uk/tc/products.php?113
http://www.pjme.co.uk/acatalog/Kawasaki ... m_End.html