Hello, I need to install my new bearings. I've watched Jim snells video which is great help. 

I'm just wondering when I heat the left crankcase is it ok to have the magneto seal already fitted? The seal must be fitted before the bearing. 

Can it withstand this temperature?

Thank you very much.

Gary

Depends on what the seal is made from. The one in your photo is likely to be Viton. Here is a chart that gives operating temperature ranges for the various materials that seals are made from

http://www.pspglobal.com/low-temperature-seals.html

Viton seals are usually but not always brown and that looks brown.

I see that it says Gas Gas on the bearing and it looks quite wide in the picture.  Is it a roller bearing?  Why did Gas Gas go to the trouble of a custom bearing?  Is there a ball bearing on the other side?

 

I would say ordinary NBR seals are fully adequate. Use original seals and bearings. Take seal out then heat the halves with hot air gun or similar (gasol?). Check temperature with an IR thermometer. I guess 100C is good. Later when putting the crankshaft back you may heat the bearing(s) to max 150C  (no more). Check with IR termometer(IR thermometer is important). IR thermometers are not expensive nowadays.

Thanks everyone for the advice.

drop the bearing in the freezer overnight.