Slippig clutch and valve liffter on a 350 scrambler.

[themoudie]

Aye George, 'Jacks the lad' and Jordan,

I can be a wee bit tight George.

Sorry to read about the legs 'Jacks the lad', I think I might be a little restrained, with those symptoms and would agree that the valve lifter would be a usefull, probably essential addition to the motor for you. Contact Nigel Lacey, he might be able to assist you if nobody on here has anything to offer. If your friend cannot find his copy of the Haynes manual, drop me a PM and I'll see what I have.

I have used the claw hammer/rubber mallet method, but was concerned of the possibility to create alloy swarf! And I agree Jordan that the slide hammer would do the job nicely. Thank you for the topic link, I hadn't made a search, it is a useful reminder of what information is available on this forum.

Good health to you all, Bill

[blethermaskite]

I have been running my widecase 350 mk3 from new in 1974 and away back in the 70s I removed the ex valve lifter because some "expert" advised me that they were a bad idea on a Ducati and if used when the engine was running could/would break the rocker! Ah well, I am now 65 years young and have arthritis in my left hip and knee (probably from all that heavy kickstarting over the years while I had the original Motoplat ignition system), so last year I refitted a valve lifter to the 350 and what a difference in terms of ease of starting, I have lucas rita ignition on the bike now which helps for easy starting anyway but when hot it would take 2/3 kicks to fire up, with the valve lifter fitted it now fires first kick 9 out of 10. As I would hope to keep on riding for hopefully maybe another 10 years this has been the best bit of retro refit I have done to the bike. I had given my original valve lifter rocker cover and lever away years ago but found the parts I used on Ebay for very little money.
Cheers,
George

[Jacks the Lad]

Garage Gorilla,

Ducati 350 Scrambler "Engine fully rebuilt" On the face of it nice to know, but as we also know there are "rebuilds" and there are rebuilds. Who did it? Did they know what they were doing? Suspicions were raised once I had the chance look over the machine properly. Front tyre fitted the wrong way round, despite there being a large arrow on the tyre wall to show which direction in should run, handlebar leavers upside down and one of my pet hates, "chocolate block" connectors in the wiring.
Then there was that slipping clutch, as advised here I thought I would strip out the plates , inspect, clean or replace as required. Only I couldn't get the cover off! Or more properly couldn't undo the 6mm allen screws or the 22mm plug in the centre of the case. Firstly the plug, this has a 14mm hexagonal socket in it, but didn't have a key that big, so I made a tool to do it by modifying a bolt so as it was a nice tight fit in the plug and then brazed on to short piece of bar, Crude I know but it worked however not until an extra two foot of tube was slid over the end of the bar. Did it really need to be that tight? And then, there were the 6mm allen bolts around the outer edge of the cover, I did have a key for those but even with the two foot tube they wouldn't come out either. Whatever are people thinking about? Got them out in the end using ratchet torque gun and even that had to be set at 200n/m before they would let go.



Home made tool to get the centre plug out and a 22x1.5mm adapter for the extractor.

I am amazed that so fine a thread (1.0mm) didn't strip out of the aluminium crank cases when done up so tight. To be continued ........

[themoudie]

OH! This doesn't sound good. I hope that my curmudgeonly instincts are proven wrong.

Has the rebuild included stud lock on all of the fastening threads?

I habitually use a wee artist brush to apply a touch of copper grease to the screw threads and then tighten to a torque of 6ft/lb or 9nM.

All the best with the strongarm tactics.

My regards, Bill

[graeme]

Did the cover come off?
Clutch,,,,
Make sure all the steel plates are flat, you can use sheet glass and a sheet of wet and dry.
The inside tangs need to be flat. (inner)
The tangs on the fibre plates need to be in good condition (outer) no wear hooks.
The outer hub in good condition, between the fingers. You can smooth with a file.
Wash the fibre plates with petrol and a brass wire brush.

The plates need to slide apart and back together to work the clutch without dragging or slipping when in use.
Oil it all with engine oil and reassemble

Copper grease is great.
The brass plug is removable to fit a timing tool to the crank end and should have a copper or alloy sealing washer like a sump plug.

I had my 450 clutch fibre plates redone with (I think from memory) kevlar and now there is no sticking even when cold and no slip.

Graeme

[graeme]

Copper grease for fasteners into alloy, not the clutch plates
In case the above was not clear

[double diamond]

The claw hammer technique just will not die! Guess this is the legacy of Mick Walker. I’m guilty of the bodge on occasion myself but a claw hammer is a a tool used for demolition. There is a Honda tool widely available and inexpensive, part number 07933-3290001, that works like a charm to remove the Ducati primary cover. Thread size is M22x1.5. An axle of the proper thread pitch would work. I have the original Honda tool and the threads are a little too short, so I run a very short Allen bolt into the threads on the end of the crankshaft. Some of the aftermarket tools appear to have longer threads so this may not be necessary.
Regarding the clutch plates, checking for flatness includes warping, such as one would observe upon leaving a record in the sun on the rear shelf of your car (you sound old enough to recognize what a “record” is...) and also checking for cupping. A cupped steel plate may lay flat on a surface plate on the concave side but will certainly lead to clutch slip. Check both sides of the steel plates. Usually, stacking all the steel plates together will reveal any cupped plates unless you’ve been star crossed from birth.
I give the friction plates a vigorous scrubbing in solvent with a toothbrush and blow dry. If the friction surfaces appear to be glazed they should be de-glazed by a wire brush or with an abrasive on a surface plate. If there are signs of friction material de-laminating, that particular plate may be finished (this would typically be a plate in the center of the stack). Replace at your discretion.
My widecase 350 would slip the clutch bump starting with the stock springs. Replaced with 450 springs and the clutch would slip (with the “torque” exhaust system) with a few cupped plates. On a 350, the clutch is marginal; everything has to be in good order and 450 springs give you some extra margin. Also, make sure the woodruff key on the primary gear hasn’t sheared; this could lead to symptoms you’re describing if the clutch checks out.

Matt

[Ventodue]

<snip> .. the 22mm plug in the centre of the case. ... Did it really need to be that tight?

No, not at all. As advised by Graeme, it should have a copper sealing washer underneath it, and be done up tight enuf to compress the washer and stay oil tight - and no more.

<snip> ...the 6mm allen bolts ... Got them out in the end using ratchet torque gun and even that had to be set at 200n/m before they would let go.

Crazy! As advised by 'themoudie', these screws should be done up tight enough to do the job they're intended to do - and no more .
That means "6ft/lb or 9nM". Or in more practical, real life terms , tight using a regular Allen key.

[Jacks the Lad]

The cover is off, I think the person who did up the case screws must have fitted the footrest, however got it off in the end. I have an old slide hammer puller
made years ago from a piece of half inch rod threaded BSW at the end, an odd bit of 25mm hexagon that I had about the workshop was popped in the lathe, turned to size, drilled and taped to fit the rod and thread cut to 1.5mm pitch. Screwed in to the cover with the slide hammer attached and with every thing clear the cover came off no trouble. The screws holding the clutch springs in place were a little "chewed" in their slots but not enough so much as to prevent them coming out with a normal screwdriver. Oddly despite them being screwed as far they would go, there was little or no resistance to undoing them.



Compared with the springs given to me with bike they were just over 3mm shorter! The cause of my problem perhaps, I will however check and clean the plates before I put them back. I did think the clutch was very light before.

[themoudie]

Aye John,

You appear to have found the culprits.

"Oddly despite them being screwed as far they would go, there was little or no resistance to undoing them." That is how the screws are supposed to be.

So, after cleaning everything with brake cleaner, checking all the plates for cupping/warping and burrs in the drive tangs and rectifying any problems. Check the clutch centre and basket for wear grooves that catch the plates rather than allowing them to slide freely and ease where necessary.

Whilst you are in the clutch, check that the short clutch push rod, two ball bearings and the long push rod are in place and in good condition, with no burrs etc.

Clean everything again, lightly oil with the current engine oil and then re-assemble, putting a friction plate first into the clutch basket. Tighten up the clutch spring screws evenly and fully. Adjust the pressure plate centre screw so that it protrudes 5mm and then tighten the lock nut. Replace the cover etc and give it a test.

I attach images of the relevant pages from the Clymer manual and can mail you them if required.

My regards, Bill