Re: Bearings Replacement

If you do replace the front bearing, I would get a sealed one.

A sealed front bearing stops fuel and air leaks. Some engines come from the factory with a sealed front bearing, some do not.

I purchased the standard rear bearing when the one in my Saito .65 needed replacing. The new bearing has performed excellent for the past

3 or 4 years.

A more expensive bearing is probably not needed.

Heat the engine case as Dr1Driver posted.

Look at my web site under Bearing FAQs for a generic, but fiarly complete bearing replacement method.

I also have ceramic bearings in stock for the OS 40-46FX for $17.97 plus shipping.

Sorry, not correct. The fit between the crankshaft and crankcase journal in the area of the intake (and possibly a spiral oil groove on the crankshaft) creates the seal. If the bearing was sealed (and they are sealed on both sides), no lubrication could get inside the race.

Dr.1 Driver "There's a Hun in the sun!"

DR,

Sealed bearings are lubed at the factory with a permanent grease. They do not rely on the two stroke fuel for lubricants. Several engines have sealed bearings as standard, such as most YS engines and other engines using crankcase pressure fed pumps.

For engines with significan front leakage (enough to cause tuning problems), a sealed bearing may solve the problem.

Interesting. I admit my expertise is with Oilite-type sleeves. I was the engineer for 8 years at a plant where they made them. I still maintain that the crank/case fit is what keeps down leakage, though. Dr.1 Driver "There's a Hun in the sun!"

I just went thru this process. I bought new bearings from Boca. My original front bearing (Saito 100) had completly self destructed. all that was left was the outer race (ceramic bearings do not like being run into the ground)!! Anyhow, the way i done the reinstall was to put the new bearings and crankshaft in the freezer over night. then i put the crankcase in toaster over at 350 degrees for ohhhhh ... maybe

15 minutes, or till the over thermostat shut it off for temp. then, using a pair of heavy gloves, i put the bearings in. the front bearing "fell" in place. then put the rear bearing on the crankshaft and put it into the case and everything fell into place. no hammering, tapping, pounding or any force at all was required.

Not saying this is the best way, or the only way, only that it worked for me and is most easy to do.

Bruce_C.

It sure is the best way, though you should skip the freezer part. It attracts moisture to the cold surfaces, which you can do without when assembling parts.

In most cases, a good fit is required. However, if the fit isn't so good, a sealed bearing may work.

All of my sealed bearings come with Mobil channeling grease installed. This grease will outlast the engine.

Look at my web site under FAQs and you will see essentially the same process. I don't think it is necessary to freeze the bearings or heat the crankcase that hot, though.

Referring to the 350ºF, I was just checking the Jett Engines site and they give the max as 325º as the heat treatment of the case begins to be affected above that temp.