Ignition side crank bearing failure?

[wence]

Just out of interest.
How many on here with 07 model 300's have had ignition side crank bearing failures?
Myself and another bloke here in Adelaide have both had the same bearing disintergrate on our 07's.
His a 250 and mine a 300.
Just curious as to whether it may have been a bad batch of bearings or just a coincidence?
Cheers Mark

[mattholew]

Old thread, but just thought i would add, my 2001 suffered a left side bearing failure.

[roostafish]

My '99 six days bike blew that bearing with only 54 miles on the bike, 8.5 miles into it's first race. Throughout that season I replaced the crank bearings a total of four times. We tried many things, after selling the bike super cheap to a friend, he blew it twice more. Finally he had to machine the crank down a couple of mils. He eventually sold the bike through our dealer. To my knowledge, the bike is still owned and ridden fairly locally.

[wence]

I had the crank balanced to almost perfect( twice as good as from the factory ), although he said the factory had done a good job beforehand.
Touch wood , it has been fine ever since.
Cheers Mark

[GMP]

Older bikes had 6306 ball bearings, and some had too tight press fits causing this problem. The newer bikes have a roller bearing. Rollers operate at a higher clearance, which is why you can detect some radial play which is normal. They also like more oil, which is one reason I like to run 36:1.

[Zeal]

Which model has the roller bearings? My 2010 ec 250 race has ball bearings on both sides of the crank?

[GMP]

The '02 or '03 to '07' I know have rollers. Aren't the new bearings sealed and use internal grease for lube, not the 2-stroke oil? "08 or '09 + correct? These would be ball bearings I suppose.

Grab the flywheel and pull up and down. If you can detect play the motor either uses a roller bearing on the ignition side or you have a trashed ball beaing.

[roostafish]

Yikes! Sealed bearings in the bottom end? They must be good, because my bike has a lot of miles on it, it's still quiet and feels tight.

[stainlesscycle]

Originally Posted by roostafish

Yikes! Sealed bearings in the bottom end?

if they are infact sealed i'm assuming sealed outside only - they gotta be unsealed toward the crank wouldn't you think?

[GMP]

No, sealed as in sealed up tight like a wheel bearing with its own lube. I'm sure its something a bit more special though. I remember Steve or Mark talking about this after a factory visit, maybe it will come up in a search. "08 or '09.