Atlas clutch wont release

Hello Bruce - I assume that it is a standard,  factory-fit 11-plate clutch.  Is that correct ? No fancy Barnet plates or other modifications ?  Check also that the pressure plate is the thin one and not the fatter Dominator plate.  Cheers for now, Howard

When  new the 650/750 clutches were  right on the edge  ,hard to operate and liable to slip if not in good condition.  After all the years  many are now fitted with poor quality pattern parts and worn or just incorrect parts , often poorly set up . I have worked on three clutches this year , all were axactly as you describe.  Superficially they looked  normal. but all needed attention to most of the parts and took a day each  to get right. . Start by checking the plain plates are flat , the center nut is tight. and the chain has some slack.

Don't forget to check that the gearbox main shaft bearing is not badly worn. Otherwise when the clutch lever is operated the shaft moves before the pressure plate.

Also check the gearbox actuator arm in case it is either not aligned with the cable hole or not giving maximum lift.

It looks to me that you have either one too many friction plates, or the wrong plates altogether for your clutch.

Your last two plates are friction to friction, try taking the last friction plate under the combination one out and then the pack will go plain friction plain pressure plate, as it should, or else discard the combination plate and substitute another plain plate with outside tangs, if you have one. Whichever, set the free play on the actuator train to suit.

Lift of the pressure plain is about 3/16" IIRC.

April 1997: Max measured atlas clutch lift .080"@ .6" cable pull,  effective is minus the adjustment clutch screw setting. On the bike the handle bar cable pull  free play reduces effective lift even more.

https://nneno.org/forum/nht-engine-drive-train/669-drive-train-slimline-clutch

As Niall has said it looks like you have one too many friction plates , or not enough plain plates !   I'm also not sure about the alloy pressure plate which looks like it could be too fat. I will have to study the parts book .

I had a similar problem with my clutch, It was dragging badly and could not figure  out for the life of me why so posted to this forum. After reading many replies someone put me onto warn rollers or warn inner clutch basket where they make contact with. To confirm I removed the outer primary chain case cover, started the bike and pulled in the clutch and sure enough the clutch basket moved outward thus partial re engagement and the problem . To correct this condition I was further told that slightly larger rollers could be sourced. There are 15 of them and they measure .250" in diameter, was told how to measure for excessive play between them and the clutch basket (I had .005 plus) purchased .252 rollers on ebay and replaced my old ones. Clutch is now perfect and to confirm started bike  with the outer cover removed and engage the clutch, the basket no longer moves out and clutch now fully disengages the drive. Hope this helps , I certainly appreciated the assistance I got from this forum.

Reducing the roller play between basket and center was an old racers dodge to reduce basket wobble and drag and allow  racers to push and  bump start their Manx Nortons a little easier. I did it to my 99 many years ago. I dont think it had much effect on the end float issue which seems  more likely  down to box bearings Very worn sleeve gear bearings allow the whole assembly to wobble and make it harder to set up the clutch with accuracy. I must remember to look for end float next time !. . Always something new to learn unless you know it all, but those guys are long gone sadly.

Hello again Bruce - It's as I feared. You;ve got after market SS friction plates or Dominator friction plates which are thicker than the SS ones. So there isn't room for the missing steel plate.  RGM sell an extended chain wheel for such eventualities. Good luck, Howard

Look like they could do with a clean up.  The wear ridges are visible in the basket and the hub  splines are choked up.   Give them a good clean up and face the basket gaps with an oil stone,  clean our the hub splines to make sure the movement of the plates is not compromised.  The build up of the full clutch needs to be addressed as mentioned by others...  

Jon