Re-timed my Sherco over the weekend and noted that the there was some play in the main bearing whilst taking off the flywheel. The engine doesnt knock or rattle - can i safely ignore it until it does or does it need an urgent fix?

Part of the cause for concern is that we discovered the bike was massively retarded as the woodruff key had become dislodged and lost in a crevice in the flywheel. this was the cause of some very soft performance. With the extra horses released, will it destroy the bearing ? The bike was so retarded, i wonder if it was actually almost advanced for the next stroke !! its a wonder it ran at all. Now at -4mm/-5mm and seems a very nice comprimise.

Note to others who may be doing the same - make sure the rubber gasket doesnt come off of the flywheel cover and wrap itself round the flywheel. it makes an awful mess!

Big thanks to Wherry for helping with the spanners

if the bottom ends not noisey i would just leave it and just keep an eye on it.

Fix it. Why wait for it to potentially do more damage.

you know the annoying saying! Prevention is better than the cure!.

Fix it. Why wait for it to potentially do more damage.

you know the annoying saying! Prevention is better than the cure!.

I would say this is sound advice

If remember correctly the early models did suffer with main bearing problems and locked up and spun in the casing

Never leave a known problem to result into a possible destruction.

Thanks all - sounds good advice. Wasnt sure if it was standard Sherco wobbles, but sounds like it needs sorting. Thanks

Caddabs,

I would not panic as yet. These bearings start out with some clearance of .003-.004 in. Although there appears to be no official published service limits here, I would expect them to come in at 2-3 times new limits.

Obviously this bike is not new, and would expect wear for age. Hopefully it has been decently cared for without a lot of water and dirt ingress into the motor. (kills the bearings)

All point being, if the motor is smooth and quiet with smooth rotation and no ragged pitted bearings roughness, you might want to quantify this thing a bit more by taking an up/down measure of things using a dial indicator on the flywheel.

Taking this logic a bit further, if one took the new limits x3, of .009-.012in then figured the added arm to the outer part of the flywheel, you may get somewhere around around .020 as a number, or around .5mm.

All estimates, as I have no hard numbers on this, but hopefully you get a take on it.

Possibly others have taken some measures here?

Thanks for the faint glimmer of hope Copemech. i'm afraid i dont have access to that sort of measuring equipment, but i wondered if you wouldnt mind a quick look at this

http://www.youtube.com/watch?v=CKrg2V8XpyQ

the knocking sound leads me to think the worst. Thanks again - Caddabs

Edited January 18, 201115 yr by Andy
Video embedded

Yep probably time to replace the Crank Bearings, When I finally did mine the crank moved up and down about as much as yours, but it also moved in and out quite a bit. With the engine off if I tapped on the clutch side of the handlebars I could hear the bearings clunking.

Hmmmm, does seem a bit clunky! Probably at or near reasonable limits, mind the fact it is non Grinding or knocking means it does still run, so does not absolutly have to happen tomorrow.

Still in the winter, so not a bad time to do it. About three choices here:

Do it yourself and make a month long kitchen table project out of it, like Zippy, Ham, and others!

Pull the motor and take it to your reputable dealer for a quick turn and get it back in a day or three, depending.

Take the bike and let them fight with it, kick back and enjoy life!

Hmmmm, does seem a bit clunky! Probably at or near reasonable limits, mind the fact it is non Grinding or knocking means it does still run, so does not absolutly have to happen tomorrow.

Still in the winter, so not a bad time to do it. About three choices here:

Do it yourself and make a month long kitchen table project out of it, like Zippy, Ham, and others!

Pull the motor and take it to your reputable dealer for a quick turn and get it back in a day or three, depending.

Take the bike and let them fight with it, kick back and enjoy life!

Advantage to doing it yourself is a month of evenings away from the wife.........

Advantage to doing it yourself is a month of evenings away from the wife.........

Also you'll build up your confidence in your spanner skills.

If you're like me...just take your time,read the many previous associated posts and when you get stuck: --type--

Also you'll build up your confidence in your spanner skills.

If you're like me...just take your time,read the many previous associated posts and when you get stuck: --type--

I just replaced the crank bearings on an 04 125 that I bought and it was seized after the previous owner sunk it in a creek. It was actually fairly easy and only required two special tools that I did not have (Sherco Flywheel/igniton puller and a blind bearing puller). I got the flywheel puller from RYP $19.00 and the bearing puller kit from Harbor Freight $39.00). I spent another $400 in parts which included a S3 head and insert, crank bearings (which are now sealed bearings), gaskets, top end rings, etc. I did not need a crank kit luckily.

Thanks all - much appreciated advice. Still pondering best way forward. Thanks again...........