1978 250 clutch woes

[Greg Barratt]

can anyone tell me proper stack order, and maybe the stack height?

mine is set up 2 steels, then 6 friction/steels.  S-S-f-S-f-S-f-S-f-S-f-S-f-S-Plate

clutch won't disengage and clutch action is EXTREMELY hard to pull.  

i set springs even and runout is good - i set springs with just barely enough to get the wire through...

clutch actuator arm moves smoothly with no side play/slop.

cable is new, magura lever, and temp routed totally loose.

any help is appreciated - thanks!

[fastwillie8568]

There is 2 rods and a ball they should measure 222mm, also there is 2 different thickness of friction plates the 250 has 8 steel and 7 friction, there is new style and old style.

[454MRW]

78 250/400's should use single clutch release rod with no balls and the end has a caged bearing on it that pushes against the clutch pressure plate.
According to my Engine Repair Instruction manual printed April 79, the 250 starts with an organic disc and alternatively 7 organic and 6 steel discs. It may be that someone added some parts to try to compensate for worn organic plates. The organic discs measure 2.75mm thick and the steel 1.50mm. The 250/400 clutch springs are about 1.7mm in diameter and 37mm long. Here is an eBay listing for a 78 250 Clutch with 7 visible fiber clutch plates, the long clutch release rod with bearing and all essential parts that you should have. Mike
http://www.ebay.com/itm/77-78-79-KTM-MC5-250cc-Complete-Clutch-Plates-Basket-Bearings-Release-Rod-/262144268527?hash=item3d090418ef:g:v3EAAOSwo6lWM8rP&vxp=mtr

Michael R. Winter
I enjoy rebuilding and appreciating Pentons!
1974 250 HS Pentons-1978 KTM 250'S
1975 Can Am 175 TNT 250 conversion
1976-78 125-400 RM's & 79 PE250 Suzuki & 2012 DR650
2007 CR125R Honda
1977 MC250 Maico

[Greg Barratt]

thanks for the info - your data should help me get it figured out - i appreciate it.  your numbers show a stack height of 28.25mm

but i have a question  - at http://www.pentonusa.org/publications/newsletters/SKT4.pdf

on page 10 and 11,  it has all different data for later clutches..
3.5mm thick fibers, 1.6x38.5 springs, and shows my plate order (on pg 11 sidebar) for mc 1978 250?  conveniently that article mentions 77 and before and 79 and after. no mention of 78...

also my clutch has the directional fiber plates...


motor date code is 12 of 77..

in that ebay auction it shows a thrust washer - i don't recall seeing one on my clutch - is that between hub and basket or between basket and case trans bearing?


my clutch looks like the one listed here - not like the one you listed.. a totally different steel basket - 6 plates with 2 steels  -

http://www.ebay.com/itm/1978-KTM-MC5-250-Layshaft-Lay-Shaft-Clutch-Shift-Forks-Etc-Parts-Lot-/361327609160?hash=item5420cdc548:g:fEQAAOSwv0tVfyTW&vxp=mtr


or this one here..

http://www.ebay.com/itm/Vintage-AHRMA-MX-1976-1978-KTM-250-MC5-Clutch-Basket-Assembly-/201375274948?hash=item2ee2e6d7c4:g:GskAAOSwNSxU8zc6&vxp=mtr

[454MRW]

I would assume that the thrust washer goes behind the basket between the case bearing and the clutch basket, but it is not shown in any of my manuals. There is no engine parts manual for 78, only the repair manual, and the 76 engine parts manual lists 7 organic plates and 8 steels discs, but no pics of the 250/400 assembly, only the 125/175, but it also lists an aluminum bottom ring on the 250/400, then the 77 engine parts manual only lists the aluminum bottom ring on the 250 gs, not the MC or even the 400. 78 only has one type of engine, no different for GS or MC, unlike some previous years apparently. Sorry, but is all I have available without dismantling a complete engine. Mike

Michael R. Winter
I enjoy rebuilding and appreciating Pentons!
1974 250 HS Pentons-1978 KTM 250'S
1975 Can Am 175 TNT 250 conversion
1976-78 125-400 RM's & 79 PE250 Suzuki & 2012 DR650
2007 CR125R Honda
1977 MC250 Maico

[Greg Barratt]

i can only assume the first link you sent is the 77 or otherwise basket.   every other example i see is the steel basket with no holes, as  mine is,  and they all show the plates stacked like mine is.  as does the still keeping track article.  i will tear into again now and see what i can find.

[DKWRACER]

As a side note, when re-assembling, the angled plates should be assembled to fling the oil away from the center, was noted from a post from a long time ago.
Good luck! Tom Brosius

[454MRW]

I found the clutch basket with holes in my June 79 Engine Spare Parts manual with 6 steel discs and 7 straight organic plates, used on the 250. The 400 used 8 organic plates. Mike

Michael R. Winter
I enjoy rebuilding and appreciating Pentons!
1974 250 HS Pentons-1978 KTM 250'S
1975 Can Am 175 TNT 250 conversion
1976-78 125-400 RM's & 79 PE250 Suzuki & 2012 DR650
2007 CR125R Honda
1977 MC250 Maico

[Greg Barratt]

i have figured it out.  mostly.


popped the roll pin outta the clutch arm assembly,  and could not get shift barrel out.  when i finally got it out, i found someone had used a piece of shim stock in there to take slop out of the barrel... so it appears to me that it was binding when under load, and moving around and blocking the pushrod..  so i grabbed one from a 75 motor i had here, and better, but still nowhere near perfect.  going to swap levers around till i find one with some real leverage.

do you measure the clutch arm disengagement point to the boss on the case around the cable hole, or to the case directly next to tthe raised boss?  there's a few mm difference between the two..

[454MRW]

The manual is sort of vague on that point:


Michael R. Winter
I enjoy rebuilding and appreciating Pentons!
1974 250 HS Pentons-1978 KTM 250'S
1975 Can Am 175 TNT 250 conversion
1976-78 125-400 RM's & 79 PE250 Suzuki & 2012 DR650
2007 CR125R Honda
1977 MC250 Maico