Hi all,

Noobie on here and am looking for some help.

i have a Sherco 290 2002 which has a noisy motor. I thought it was piston slap so I've taken the head off to have a look - I've noticed that there's lateral play (no up and down play) in the crank. i.e If I get hold of the top of the crank I can induce a "wiggle" from side to side - I'm assuming this ain't good !

So have decided it's time to replace the big ends and probably give the old girl a freshen up on top with a new piston and replated bore. Piston and bore bit is easy enough but am looking for some advice on replacing the big ends. Is it an easy job or am I better off shipping the motor to a dealer to get it done ?

Cheers

Steve

I did changed the main bearings on my Y2K Sherco 290 a couple of years back, you'll need an extractor for the stator but the rest is pretty easy.

Have a a look on the Shero website for Wayne's excellent manuals which descibe the whole job step by step with colour photos etc.

I would check the wear on the piston as I only changed the rings as the piston was fine, and it still hurts to kick the thing over, loads of compression!

That and new gaskets all round and it'll serve you well for many years to come.

One thing I probaby could have done at the time but did not was change the clutch basket (I did the plates) as that is quite noisy when the clutch is out.

Mick

There should be a little play side to side as the connecting rod big end has to be self centering to some extent. If you can feel no clear play (clunk) when the rod is pulled and pushed (stop giggling you adolescents) it

Mine Sherco 290 '03 is also noisy, I wondering if Crackerjack had any result with his rebuild?

I found it hard to believe that after 6 years the main bearing are already gone. I have oldtimer 2T scooter with 50 years old bearings that stil doing fine.

I found it hard to believe that after 6 years the main bearing are already gone. I have oldtimer 2T scooter with 50 years old bearings that stil doing fine.

Bet your not running it at 50/80 : 1 though.

Bet your not running it at 50/80 : 1 though.

Bet your not 'trialing' your scooter through streams either.

My Sherco was 18 months and needed new main bearings before it wore out it's original back tyre. The last engine rebuild I did was 20 years ago but I did this one myself and it was no problem.

The Ryan Young website manual was excellent. Got a flywheel puller from those nice people at Trialsbits.

What I learned the hard way was;-

There is a definite art to getting the engine out of the frame. Remove as much as possible in situ.

Remove both the crankshaft end nuts with the engine in the frame. I made a holding tool but an impact wrench is far easier.

Scraggydog

I have no experience with the durability of those new trialmachine but still I find it hard to believe that the tyres last longer than the bearings.

Bet your not running it at 50/80 : 1 though.

Bet your not 'trialing' your scooter through streams either.

Isn't that what these trial machine are build for?

So is there some guide or rule after how many hours of use an engine rebuild is needed?

And what is needed for a rebuild? new seals, gasket and bearings? Or also new crank and piston,....?

Only 2 things kill bearings in engines on trials bikes & they're dust &/or water.

First is caused by sloppy maintenence ie filter not fitted right/torn or dirty, take your pick.

Second is caused by us setting sections in streams, if you drown it don't just put it away wet, dry out airbox & fit dry filter then run for 1/2 hour minimum to heat all the water out of the bearings

As far as life of the rest of the engine goes there is no hard & fast answer to when to replace parts like with mx bikes, top guys do piston & rings once a year if they don't sell the bike before then but most guys who upgrade every year or two may never get inside theirs

Normal strip for bearings will need all gaskets,crank seals & bearings replaced along with anything else you feel like doing & is not hugely expensive

Only 2 things kill bearings in engines on trials bikes & they're dust &/or water.

First is caused by sloppy maintenence ie filter not fitted right/torn or dirty, take your pick.

Second is caused by us setting sections in streams, if you drown it don't just put it away wet, dry out airbox & fit dry filter then run for 1/2 hour minimum to heat all the water out of the bearings

Thank you for pointing that out again Tony!

Now I am not the only one who TOLD YOU SO!

Only 2 things kill bearings in engines on trials bikes & they're dust &/or water.

First is caused by sloppy maintenence ie filter not fitted right/torn or dirty, take your pick.

Second is caused by us setting sections in streams, if you drown it don't just put it away wet, dry out airbox & fit dry filter then run for 1/2 hour minimum to heat all the water out of the bearings

As far as life of the rest of the engine goes there is no hard & fast answer to when to replace parts like with mx bikes, top guys do piston & rings once a year if they don't sell the bike before then but most guys who upgrade every year or two may never get inside theirs

Normal strip for bearings will need all gaskets,crank seals & bearings replaced along with anything else you feel like doing & is not hugely expensive

3rd thing - low ratios 2 stroke.

You can guess who's found out the hard way on the water thing, also managed to distort a cylinder 1 time due to very hot engine & not properly sealing of the rear guard.

Good quality oil helps with the life of bearings, never been brave enough to run 100:1 like some people though