SWM TL clutch upgrade

[Twinshockwobbler]

Hi all, new on here but have been looking at the thorny subject of SWM clutch upgrades on the TL models.

after pulling the clutch to bits several times and not being able to improve the standard set up i by chance got talking to Gary at Sportax Racing, he was able to supply the Aprilia type kit with 12mm ball bearings and also some standards generic to all motors, standards clutch springs. The springs are lighter than the 37mm ones fitted and also shorter at 33mm. The difference is massively noticeable ( just about one very strong finger😁). Apparently the 37mm springs are classed as heavy duty and due to their bulk when compressed, they can foul on the basket and posts. I also noted that on some of the friction plates, the material fouled the slots in the basket causing drag. This is easily cured with a bit of filing. The clutch is now drag free and far better to use, the 12mm ball kit also can be used on the 350 Jumbo and early fourstroke motors as well. Hope my first post on here is helpful. Oh and always use genuine Rotax crank seals,you really have to press them in compared to the push fit of some aftermarket ones👍 https://sportaxracing.co.uk/shop/clutch-kickstart/item-12-spring-239-625/

[iconic558]

Much of the issues with these SWM clutches is simply down to incorrect clutch lever and perch, decent cable correctly routed, proper set up, roughed up steel plates once they get old and polished and draggy. 

Need to be OE Domino, but they get broken and owners go cheap, then the bikes change hands and, well you know. My mate had a brand new Tl320 back in the day and the clutch action was a revelation after Spainish ones. 

Out of all the twinshocks I've owned my TL320 had the lightest pull and smoothest consistent operation of all of them, Sherpas, Cotas, Honda TL, Ossa, even my Beta Rev I kid you not. 

 

[Twinshockwobbler]

Hi Iconic, yes your right about lever selection. Even Domino levers have their differences. I’ve just fitted a Domino lever blade with a pivot to nipple centre of 24mm and the difference in pull again is huge , the lever blade I took off it was 30mm. I suppose manufacturers bulk buy to a price so some bikes may have had these 30mm levers for that reason.Amal levers also do a 24mm pivot and their a nice lever but they need to be pulled almost back to the bars to clear all the drag. Other than maybe experimenting with different clutch springs, I don’t think I can improve on what I’ve now got other than finding a txr or climber outer case but if I’m honest I don’t think I’m that far off that level of lightnesses now, my son’s bike has the txr set up and it’s not much lighter

[jimg]

Wobbler, thanks for sharing.  I recently acquired a Jumbo (350) late model assembled in the USA.  Anyhow, the ball bearings on my bike are 12mm, so I got lucky.  Of course, my bike already has the clutch lightener arm and I'm using an "EZ-pull" lever.  Right now, it's a one finger pull, but I'm curious to using the smaller springs that you made reference to if it will make the pull lighter.  I just don't want the clutch to slip with the big 350 motor.  I'm in the process of installing new Rotax clutch plates (fiber and steel).  I believe I'm going to need to use 6 fibers, 5 steel, and 1 steel at 1.5mm (outer).  If your using stock top triple clamp, I'm using the "powermadd" handlebar riser that accepts fat bars... this makes a nice difference ergonomically, especially if you've lowered and went back with your footrests.  What length shock are you using on a Jumbo? Right now, my bike has 340mm length.  Regards.    

[Twinshockwobbler]

Hi Jimg, so sorry for a slow response to your questions. 
firstly my bike isn’t a jumbo, it’s an 83 TL320. Rest assured  the shorter springs won’t cause slip on your 350. At the end of the day both 240,280 and 350 are downrated mx engines that would need the strong springs for that application and furthermore theyd be clutch less shifted so a heavy clutch wouldn’t be noticeable. I think 340mm is the stock shock length but I run rockshocks 360mm with no noticeable difference, if anything you gain a tad more travel when the bike is weighted. I also swapped the well tired fork springs for a pair from REH, a hard one in one leg and a medium in the other, they are shorter than the originals by about 20mm but a longer spacer solves this. As long as the springs are longer than the travel your fine. I recently rebuilt the engine and fitted a clutch hub off an Aprilia TX311, this has the last plate as part of the casting so uses one driven plate less than the SWM clutch and has a far superior actuator bearing. I get no drag at all with this set up even if the bike is stood for a while. If you go down this route just make sure you get the 3mm thrust washer that fits under the splined tab washer, the SWM uses a 1.5mm thrust washer with the standard set up. Hope there’s some useful info for you all.