Vintage Dirt Bike Q & A

Installing new crank seals and bearings in engine. Do you guys lube the seals with heavy grease first or just use 2 stoke oil? I want to be sure they get a good start in life to last a long time.
Other question: Is it ok to use bearing for right hand end of crank that came with left side shield or should I pop the shield off? I figure maybe it might help with sealing the crankcase from the transmission.

I read this in Rick Sieman's "Tips and Tricks for your Honda 125 Elsinore":

"When installing new main seals, you must slip the crank into the seal at least five times, regreasing it each time. Otherwise, the odds are you’ll pinch the seal when installing the crank. If you don’t do this, the motor will only run five minutes hard before it blows."

Here's the complete article:

http://articles.superhunky.com/4/37

I didn't realize the right main bearing had a cover. Maybe it's to keep the seal away from the inner bearing race? If so, I'm real glad it's there. My MR uses the same bearing, and at one point the ignition started double-sparking and created explosions in the crankcase. The left seal blew out, but the right-hand one survived and is still working fine, maybe because of that cap leaving it with no place to go.

I'd leave it in place, I think. Without it, it might be pretty easy to drive the seal in too far and contact the bearing.

Ray

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'74 CR125M (175cc), '75 MR175, '82 RM250Z, '08 YZ250F, '14 Zero FX electric, '14 Zero MX electric, '18 Alta MXR electric

Insert bearing shield the tapered side goes towards the bearing.

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Dirt Bikes