2022 Sherco ST250 Fajardo - Bit of clutch drag

[lowside]

5 hours ago, lemur said:

When you have a small volume of oil that has no filtration or water separator, the logical best practice would be to change the oil out frequently.  The transmission oil I have been using successfully for decades in dozens of different engines costs about 5 bucks to change and it works great in winter or summer. Suit yourself but no transmission oil that should be changed frequently is worth 24$ per litre, you're paying outrageous money for packaging.  

If you want to know what is in a packaged chemical product the best place to start is the MSDS (Material Safety Data Sheet) it's the only place they are compelled to be 100% truthful about what they are selling you.

 

Im not averse to saving a few quid.  Not sure whats available locally though or at what sort of price.  Things here are generally very expensive across the board.

[Tr1AL]

On 7/23/2023 at 1:56 AM, bikerpet said:

First be sure the lever is setup well.
I'd adjust the lever out as far as you can comfortably reach, then ensure there is a couple of mm of totally free play before the pin starts to push the piston to ensure the fluid can return properly.

If there's still the same drag I'd be trying some different oils. If Sherco call for Dexron 6 as cascao says, then try that - the factories know their bikes.
I have found Putoline N-tech Trans GP pretty good, but I'm sure Gro and all the other common trials oils are good too.
Putoline GP10 has a low viscoisty index, so it's viscosity will vary a lot between hot and cold - ignore cold drag and make sure the bike is well warmed up before checking the drag.

Your "swarf" comment is concerning. If it's superfine powder / smooth paste then it's fine, probably just wear from the clutch plates. If it's actually swarf that feels gritty or worse then there's a problem that needs fixing ASAP.

75W gearbox oil is completely different from 75W engine oil. Why on earth they'd use the same rating numbers for a different rating system is beyond me! Setup to confuse people.

GP10 75W oil has 100C viscosity of 5.5.
Typical ATF Dexron 3 is around 7 - 7.5.
So the GP10 is actually considerably lower viscosity than the ATF DIII.

Here is interesting information for comparison Dexron Vl  or Dexron 6 is 6.4 @ 100C  , While this next one is the big surprise  Motorex Trial 75W Gear oil specially developed for the new KTM GasGas GP box / wet clutch has a viscosity of 14.2 @ 100C . I have put the Motorex Trial specific oil in a pre KTM GasGas Pro and the Clutch was a little draggy under normal use with it adjusted correctly with the usual on/ off action. So if you are looking for less drag then Putoline GP 10 would be the best bet in theory.

[lemur]

Does anybody know the normal operating temperature of a 2-stroke engines transmission oil?  

[bikerpet]

On 11/27/2023 at 2:00 PM, lemur said:

Does anybody know the normal operating temperature of a 2-stroke engines transmission oil?  

Not I, but I'd be surprised if it was much over 50C really. 60C hot water is standard and really very hot to touch. I don't make a habit of sticking my hand on the gearbox but it never feels as hot as that when I do touch it.

[Tr1AL]

I do not think that what average running temperature the transmission oil in a Trials motors  gearbox is matters in relation to the viscosity of the oil tested at 100 C is . lemur is I think suggesting that this viscosity test is not therefore a good metric because the gearbox oil does not get to 100 C , but when the clutch has been slipped and  thrashed for example starting off from a standstill  heading  up a hill in very muddy conditions the oil will likely be around the 100 C for a while between the plates so has some relevance , the viscosity of the brands mentioned @ 40C follow the same pattern of viscosity so will give a theoretical idea of what brand with a 75W rating could give  you less drag in your bikes clutch when it is set up exactly as it should be to operate as it was designed to.