GS 850G Different drive shaft / output flange

[rexb]

I have just dropped a replacement motor into a 1981 GS 850G.All went well until I tried to bolt the shaft plate to the output flange which did not line up.So I was left with 2 options - change the ouput flange or drop in the drive shaft from the replacement motor.I opted for the compatible drive shaft which slotted in O.K.
I have noticed minor play when turning the output flange to back wheel movement.The spline on the relacement shaft looked good.Is the rear final drive also slightly different - would the option of changing the output flange been the better choice?
Appreciate any comments from anyone who has keener knowledge re: shaft drive system.Apparently Suzuki made the change mid 1981.
Regards Peter.

[Nessism]

Peter,

Good work figuring out the change in the power drive system. I thought the change hit for the 1982 model year, production for which typically starts in the second half of 1981, but I could be wrong. As for freeplay in the system, some freeplay is normal but it's hard to judge how much is too much. Could you measure the freeplay in your bike and then someone here can check their bike and report back?

[bwringer]

You'll be fine with the driveshaft from the donor engine. My '83 is wearing an '81 engine and driveshaft...

[Dogma]

I just checked my '80 850GL. At the tread farthest from the axle (the largest diameter of the tire), I had less than 5cm [2"] of movement with the bike in 1st gear. If you have more than that, I'd look at the final drive spline mounted on the wheel. These are notoriously difficult to check while installed (what you can see looks good, even when they are destroyed), so search the forum if yo need to look into that issue.