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900cc XL flywheels into '52k cases?

PostPosted: Wed Sep 04, 2019 11:00 pm
by BackroadCycles
Hi all!

So I have gotten my '52k cases in the mail and I was wondering if it's possible that I can graft 900 flywheels into my K cases so I am able to use a later sprocket on the crank?

I was playing around with putting them in and it seems that they are shifted towards the pinion side about 0.0625" to 0.125" but the pinion shafts line up well together. Has anyone gone about doing this? I really don't want to go about doing an expensive rebuild to my 52 flywheels.

Re: 900cc XL flywheels into '52k cases?

PostPosted: Thu Sep 05, 2019 9:22 am
by Noot
1. XL flywheels have heavier counter weights (so you would want to dynamically balance your assembly with the weights from your lighter K pistons) 2. I just did this same thing, and modified my sprocket shaft, Timken race location, front engine sprocket, sourced a special seal, re-balanced my XL flywheels, and still trimmed a bit off the right case (since it's shaped different near the cam bushings) for clearance. I have a the nicest set of '52 flywheels, oem rods, all rebuilt with NOS components, Sonnax rollers, correct end play - I shouldn't sell 'em (had them for 20+ years) - but I'd let them go for $450 + shipping. Send me your email and I'll send you pictures . . . :)

Re: 900cc XL flywheels into '52k cases?

PostPosted: Thu Sep 05, 2019 10:33 am
by 55panman
Noot, what did you have to do to the sprocket shaft, Timken race location (moved out??), front engine sprocket and what was the sprocket shaft (I assume) seal you sourced? I'd appreciate the input on this as I have to do the same to a bottom end. Thanks much, regards, Ron

Re: 900cc XL flywheels into '52k cases?

PostPosted: Thu Sep 05, 2019 10:44 am
by BackroadCycles
This would all be interesting to know, I'm considering having Noot rebuild my crank but if it doesn't seem hard to do the modifications to fit the crank into my cases I'll do that and ship the flywheels out for rebalancing.

I have a full machine shop at my disposal