THE ENGINE BLEW UP ON MY 650 PRARIE, DEALER WANTED 3 GRAND TO FIX IT SO I BOUGHT ONE ON-LINE AND PROCEEDED TO INSTALL IT. IT WAS FROM A 650 WITH INDEPENDANT SUSPENSION SO I HAD TO MODIFY AIR CLEANER MOUNTS SLIGHTLY, GOT EVERYTHING BACK TOGETHER BEFORE I FOUND OUT THAT THE OUTPUT SHAFT IS ABOUT AN INCH SHORTER THAN THE OLD ENGINE. I HATE TO THINK ABOUT CHANGING THE OUTPUT SHAFT BECAUSE OF THE TROUBLE INVOLVED WITH GEAR ALIGNMENT. HAS ANYONE DONE THIS? OR SHOULD I JUST SELL THE ENGINE AND LOOK FOR ANOTHER??

 

If your new (used) engine is in a good shape and you already went though that much trouble, go for it. I would use the same original number of shims as they were on your original engine and see if the backlash and tooth contact patter would come out just right.