Motoscrubs.com

Hi there, I'm about to replace the bearings in the main cases on my 250 scrambler.

Firstly any clever ways to extract the 'blind' bearings would be great.

I'd like to only heat the cases once, unless advised otherwise.

Secondly, according to the bearing chart on the main motoscrubs tech page, two of the chain-side bearings (6203 & 6204) have a seal one side.

I've ordered the bearings and removed one seal from one side of each bearing. So the newbie question is which way round should the sealed side of the bearing face.

Presumably the seals should be on the outer side of the engine, with the exposed side inside the cases/crank side. Otherwise how do they remain oiled?

Any advice would be great, ready to start building the engine back up at last.

Thanks

Heat the cases in an oven with the inside of the cases facing down. If you’re lucky, the bearings will drop out. If they don’t, you’ll need a blind bearing puller for the right side mainshaft bearing. All the others can be tapped out or, better, pressed out. Hopefully, the new bearings (cooled in a freezer) will drop right in the heated case. If not, installing with a press is preferred so the bearings go in square with the bore. It’s considered good form to install the bearings so the bearing numbers can be viewed when installed. The exposed side of the sealed bearings should face the inside of the case so the bearing can receive lubrication. There should be a shim behind the countershaft bearing. If you cool the bearings in a freezer before installation, be sure to blow out the bearings with compressed air once the case cools; condensation will form on the bearings and can lead to rusting. Lubricate immediately. Matt