Hi Cope,

The big and small's are as tight as a ducks ar**....I can't fault them

I have checked ring gap but not the piston gap. But I have measured the diameter of the piston at 0.01mm less than stated on the top of the piston.

Also the piston is in great condition. Hard to describe but the sides of the piston have a patten in the metal you can see and feel (like a fine file) and at no point has this pattern worn smooth.

I addition to this I don't see the piston, or the small end being a big job to do...should I need to at a later time. Sherco parts have still not arrived...but the new piston rings should be in that parcel.

One of the reasons I'm taking my time is because if I wait a while I might be able to change the Frame over at the same time. I'm having my old 250 frame fixed by a "master welder"... I recently counted 7 places where the old 125 frame has been poorly welded by the previous owner. So it would be nice to get that old frame replaced now.

Best of balance.

Neo

Hi Cope,

The big and small's are as tight as a ducks ar**....I can't fault them

I have checked ring gap but not the piston gap. But I have measured the diameter of the piston at 0.01mm less than stated on the top of the piston.

Also the piston is in great condition. Hard to describe but the sides of the piston have a patten in the metal you can see and feel (like a fine file) and at no point has this pattern worn smooth.

I addition to this I don't see the piston, or the small end being a big job to do...should I need to at a later time. Sherco parts have still not arrived...but the new piston rings should be in that parcel.

One of the reasons I'm taking my time is because if I wait a while I might be able to change the Frame over at the same time. I'm having my old 250 frame fixed by a "master welder"... I recently counted 7 places where the old 125 frame has been poorly welded by the previous owner. So it would be nice to get that old frame replaced now.

Best of balance.

Neo

Accross the piston skirts about 1/4 the way up from the bottom is whre the measurement must be taken, yet it is all irrelevent unless you have a precision bore guage to compare the readings. Next best thing is to just try and guage things on clean and dry bore using feeler guages if possible. But if all looks well with little scoring from the dirt, it is probably ok. These things are kept quite tight tolerance at about .02mm new limits !

Bugger, bugger, bugger (forgive my Aussie slag! )....

I got the parts...Put the two sides back together again...Fitted all the seals but when I got to pressing in the last one (the Viton Main bearing seal) it tore on the outside edge of the seal on a sharp edge...I hadn't noticed before . Had to split the case again to get the seal out and that's costing me another week before I can get a new seal and reassemble it all again

So the reconstructive surgery will resume next weekend

Best of balance.

Neo

Edited April 11, 200917 yr by Neo

I'm a bit confused here Neo?? ...(if your Sherco engine is the same as mine)..you should assemble the seals before putting the cases back together,use electricians-tape on the crankshafts just in case there are any sharp edges (keyways etc..)and then lube the seals/shaft for assembly.

I once had to change the mains seals (from nitrile to viton) from the 'outside' and all I had to do was wind 2 self tapping screws into the seal and pull the screw-heads out, with a pair of pliers, to pop the whole seal out.

I hope this is relevant...err... for next time maybe?

Hi Ham2,

You are correct, they are the same. Someone previously mentioned that they had fitted the seals after the shafts went through and I thought this was a good idea. I did this on all the seals. Because I thought there was less chance of a heavy shaft cutting/damaging a delicate seal edge that way and I still stand but that idea. It works quite well. Although you do need to use a long reach socket on the Flywheel side. After taping the the shafts I greased the seals inside and out. The seal was even going in "fair and square" before it tore....just my luck I suppose

Best of balance.

Neo

Hindsight is always 20-20!

Some seal seats can have sharp edges or burrs, chamfer edges lightly as needed, and depending upon the application, some lube or even sealer may help prevent tears on the outer sealing surface, too much friction when dry!

I have knackered a few in my time! Oh yes!

Hi All,

How much should I tighten the...Case bolts and Main drive pinion nut?

Best of balance.

Neo

Hi All,

How much should I tighten the...Case bolts and Main drive pinion nut?

Best of balance.

Neo

Obviously you failed to save that list I worked up sometime back! So did I !

96 in/lb on the 6mm bolts, 72 ft/lb on the crank nuts= for dry threads and reduce accordingly for lubricated threads up to 20%. From memory!

Obviously you failed to save that list I worked up sometime back! So did I !

96 in/lb on the 6mm bolts, 72 ft/lb on the crank nuts= for dry threads and reduce accordingly for lubricated threads up to 20%. From memory!

I read somewhere ,don't know if it was Loctite monthly or LoctiteWorld ;

That if you're using liquid threadlock ,loctite style, then you drop the torque by 18% !

I read somewhere ,don't know if it was Loctite monthly or LoctiteWorld ;

That if you're using liquid threadlock ,loctite style, then you drop the torque by 18% !

I've got some copies of sheep dentistry you might be interested in !

I've got some copies of sheep dentistry you might be interested in !

Baaahaaah...any readers wives pages?

I did run a check sometime back on the factory installed 6mm case bolts on my bike. I have always tried to be a bit cautious about running these bolts in ali threads. It seemed to me that these broke loose and came back to torque at about 75 in/lb and these had not been disturbed or treated with grease or anti sieze as I will normally do the outer cover bolts.

These such things I will normally just do hand tight using a short 1/4 drive ratchet by hand tight and feel.

I just mark the crank nuts and put them back in place or just slightly beyond using an air gun, much easier than trying to hold stuff and pull that much torque by hand. Must be gentile!

72 ft/lb on the crank nuts= for dry threads and reduce accordingly for lubricated threads up to 20%.

Hi Cope,

Is this correct..."Seventy Two Foot Pounds"?... I'm up to about 15-20 ft/lb and it feels far too tight to me....and it's making really nervous

Best of balance.

Neo

Edited April 19, 200917 yr by Neo

72 foot/pounds is correct, in other words its hell tight although marking everything before stripping then tightening so marks line up is just as good. Always easiest with motor in frame to steady it if possible

72 foot/pounds is correct, in other words its hell tight although marking everything before stripping then tightening so marks line up is just as good. Always easiest with motor in frame to steady it if possible

Ok...I think ...but just to confirm, we are talking about the six 5mm bolts that hold the crank casings areas together, behind the flywheel...right?

Best of balance.

Neo