16 replies to this topic

[Stilly]

Hi all ? Sherco 250 2004 clutch new plates and friction plates, new springs, filed out the grooves in the basket as advised to, ipone oil as recommended, now it's doing my head in rides ok in 123 gears 4 an 5 it slips when you give it a fist full what to look at next any help much appreciated thanks all.

[Baldilocks]

check there is some free play at the lever, it needs a bit of clearence.

[John.B]

Like Baldilock says, are you sure there is freeplay at the lever end? There are two adjusters, one for the clutch adjustment and the other adjusts the position of the lever, ie closer or further away to handlebars. This one can cause problems if the lever is set up too close to the bars. Done it myself before, tried it at home and seems fine, got in fourth across fields or roadwork and slips like mad.

[copemech]

Lots of possibilities here, and I recently had reports from a few that thated the pushrods in the motor were a bit too long, yet I do not fully understand the operational condition you describe. "Full Fist" can mean different things.

Do you mean that you are already shifted into gear 4or5, clutch fully released then full power and it slips? Or, you are shifting on the fly with a quick pull and release of the lever and get a minor delay untill full engagement.

Or do you mean you can shift up into 4or 5, give a full rev and pop to slam the clutch and the revs continue and the clutch will not catch the motor untill you back off the throttle, possibly then slipping again on reapply of power.

As stated, residual pressure in the hydro side due to the lever not allowing the MC piston to return fully can be an issue. So can dirt under the MC boot at the lever not allowing a full piston return which holds residual pressure.

If on a full throttle pop in the high gears you only get a minor slip before it hooks up, but does, then this could be normal with the oil as it can take a slight bit for the oil to squish out due to its viscosity. A thinner oil or a mix of the gear oil and ATF can quicken this, or dependant upon temps, just use ATF, but this also quickens the reaction in the lower gears and may reduce "feel". As having the motors gear oil up to decent operational temps can change the clutch reaction as well due to the oil flowing better as it warms up and thins out.

[Stilly]

Hi sorry about my Geordie twang ha ha, when I say fist full what I mean is, I will be in 4th gear riding across the field open up the throttle and she just slips so you have to slacken of a bit to let you get going, clutch and springs from offroad moto in Blyth, ipone oil, lever has plenty play and everything has been stripped an cleaned I can live with the problem but it dose not seem right for it to be ok 123 gears then 4th and slips it's a pain in the neck really.

[chewy]

I only suggest this because I had the problem of simple piston sticking in the master cylinder on a 10 month old bike. worth a look (it's only a matter of the circlip and pull the piston out if the fluid is black and "canky" and or the piston is offering too much friction you will hopefully feel it, I found that laying the bike on its side so that open end of the m.cylinder is up you can just prime it before refitting the piston, beware dirt & crud will damage the ruber seals I found dirt under the rear seal which made it tight in the cylinder), I 've never heard of sticking slave cylinder (but I lead a sheltered life), brake calipers pistons stick so perhaps clutch slave ones do too.

[copemech]

This is true as Chewy states, and I have seen them with a lot of dirt unnder the outer boot where the pin on the lever goes into the M/C.

Quick ck for a hydro system holding residual pressure(such as described) would be to ride the bike, make the symptom occur, then come back and crack the bleeder port on the clutch slave to see if it spits at you. Quick open and close so as not to induce air.

Then restart without toutching the clutch, just simply push off and put into gear and run it up through without using the clutch to see if the same problem occurs.

If it does, then the problem should not be related to the hydro side holding pressure, yet something in the mechanicals.

[copemech]

As an addendum to isolating this stuff, the thoughts on the mechanical side with pushrods being too long and such.

The slave cyl is basically self adjusting, yet could bottom out and retain pressure if pushrod was indeed too long. It consists of an inner seal and piston that moves, and an outer seal that keeps oil in and crud out of the motor!

A quick test would be to back out the two retaining screws by one turn(1.25mm) or even half that, pump the MC back up to displace the distance, and see if things change when riding.

The total piston travel on this thing is minimal, and the normal operational range is maybe a couple mm from full engagement to full release at best?

Another thing I have found as a possibility is the last friction plate installed incorrectly, not in the proper groove, but in the odd recess cut into the basket.

The only bike I seen like this came this way from factory, yet never had a real issue, yet clearances are tight enough that it could be. This situ could potentially snag up the works by putting the last plate in a bind.

[HAM2]

copemech, on 27 November 2010 - 03:57 AM, said:

Another thing I have found as a possibility is the last friction plate installed incorrectly, not in the proper groove, but in the odd recess cut into the basket.

The only bike I seen like this came this way from factory, yet never had a real issue, yet clearances are tight enough that it could be. This situ could potentially snag up the works by putting the last plate in a bind.

You've got my attention now Copey??
In your opinion where does the last plate sit?
Is it lined up with the rest of the pack or offset (by 10-ish degrees)?
I'm at work,my bike is not,but I seem to remember my bike has the last plate offset like this
workshop manual??Page 9 photo 10.

Edited by HAM2, 27 November 2010 - 01:14 PM.

[copemech]

HAM2, on 27 November 2010 - 01:03 PM, said:

You've got my attention now Copey??
In your opinion where does the last plate sit?
Is it lined up with the rest of the pack or offset (by 10-ish degrees)?
I'm at work,my bike is not,but I seem to remember my bike has the last plate offset like this
workshop manual??Page 9 photo 10.

To be honest, I am a bit unsure about this, as my '07 came this way, yet cannot figure the logic behind it.

At this point, best I can tell is it makes no difference unless for some reason with the tolerances,the stack height of the clutch pack was low due to wear or whatever. No exact specs but I seem to recall the clearance being fairly close on the top one, which is why I brought up this as a potential issue, yet mine was fine.

As I reassembled mine, just put it back to a conventional state, all lined up. No prob!

I should add I do not recall this positioning on prior bikes, but yet? And you notice no mention of it in the published blog you put up!!!!

Go figure? Long as things work, I kinda leave them alone!

[trialsnutterman]

I thought offsetting the last plate might have something to do with the force distribution into the basket, with the offset plate there might be slightly less strain on the basket.

[HAM2]

Hmmm?..food for thought.

Where do the rest of the Sherco peeps 'sit' the last clutch plate?
Does it make a difference?
Chime in if you've got the time.
Cheers,
Wayne

[Stilly]

I have stripped mine down again put it back together the same as it was, no clutch plates looked to be offset, I have removed the master cylinder cleaned it ground a little off the push rod, fresh oil back together sparkling like new but still slips in top gears, I have been told it could be the clutch basket now, I have to take the hole basket off and the bike shop is going to measure it for me could this be the fault ? When I do this I will let you all know cheers for all help

[copemech]

Stilly, on 04 December 2010 - 09:16 AM, said:

I have stripped mine down again put it back together the same as it was, no clutch plates looked to be offset, I have removed the master cylinder cleaned it ground a little off the push rod, fresh oil back together sparkling like new but still slips in top gears, I have been told it could be the clutch basket now, I have to take the hole basket off and the bike shop is going to measure it for me could this be the fault ? When I do this I will let you all know cheers for all help

Did you try cracking the bleeder to release any residual pressure, as suggested? If so, and you have new factory springs installed, then the only thing I can think of mechanically in the basket would be severe grooving from the previous plates where they contact the basket, not letting things settle and snagging the plates. A file will fix that!

If I can run mine on 4 springs without slippage, you should easily be able to run 6 springs, I would think!

[copemech]

trialsnutterman, on 30 November 2010 - 01:04 PM, said:

I thought offsetting the last plate might have something to do with the force distribution into the basket, with the offset plate there might be slightly less strain on the basket.

The only other logic I can apply to this is that the last friction plate being set there in a position of minimal movement could have something of a stabilizing effect on the pack, particularly at extreme high rpm where chatter could develop.

I have heard clutches chatter up at revs, make an odd sound and drag a bit, though disengaged. 10,000 + rpm is a non issue here.