crankcase on a yz250?

Question

can u pull off and put back the crankcase without using the separating tool and the installing tool without damaging the crankcase

Answer 1

yes you can but it is tricky. but you will need the flywheel puller and a clutch tool will help.

Answer 2

SEPARATION TOOL
1. If you want to remove the RIGHT side crankcase only, say, to repair the transmission, then the crankcase separation tool is usually not necessary. In this situation the crankshaft will remain in the LEFT side crankcase. I've never had to use the separation tool to remove the right case only.
2. If you want to remove the LEFT side crankcase from the crankshaft, say to rebuild the crankshaft, then yes, you will need the separation tool to push the crank out. If you try to bang the crankshaft out, the force needed will bend the crankshaft, (don't ask me how I know this). The reason for this is that the left crankshaft bearing is a PRESS fit to the crank, where as the right crankshaft bearing is a SLIP fit.

INSTALLATION TOOL
1. You only need the installation tool to pull the crankshaft into the LEFT side crankcase. The reason again is that the left crank bearing is a press fit, where as the right bearing is more or less a slip fit. Once you pull the crankshaft into the LEFT case with the installation tool, then the RIGHT case will slip on with *mild* persuasion from a rubber mallet.
2. If you try to bang the crankshaft into the left case without using the installation tool, you WILL tweak the allignment of the crankshaft which will cause vibration and reduce the life of the crankshaft and main bearings.

My Advice:
1. Buy the tools if you plan to repair your bike alot.
2. If this is a one time deal, then either have the bike shop do the whole repair, or if you enjoy learning about the guts of your bike, then do all the work yourself, and just take the engine down to the shop and have them do the crank removal and installation. A decent shop won't charge you too much since it only takes about 5 minutes to either remove or install the crank. Good luck.

-Dave

Answer 3

the cases are pretty flimsy and distort. you either get oil leak into crankcase from transmission or air leaks from outside. if either of these happens you need new cases. strip as much as possible and find a Yam dealer who will lend you tools, take engine to them and use workshop (or just make some from bar stock, there are tapped 8mm holes in case for puller)pulling crank back into case prevents damage to main bearing

Answer 4

Yamaha Crankshaft Installation Tool