Slippig clutch and valve liffter on a 350 scrambler.

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Eldert
Posts: 771
Joined: Sun Nov 01, 2009 3:23 pm
Location: Hazerswoude Rijndijk Netherlands

Re: Slippig clutch and valve liffter on a 350 scrambler.

Postby Eldert » Sun Oct 13, 2019 10:35 am

Jack

re clutch springs : the shorter one is the stronger one . its made of thicker springwire .

they are used in the 450 ' s

Eldert

Ventodue
Posts: 952
Joined: Mon Mar 08, 2010 3:23 pm
Location: Montpellier, France

Re: Slippig clutch and valve liffter on a 350 scrambler.

Postby Ventodue » Sun Oct 13, 2019 10:53 am

Jacks the Lad wrote:<snip> Compared with the springs given to me with bike they were just over 3mm shorter!

Just so that you know ...

(Edit: as per Eldert above ... :) )
The 450 got stronger/longer springs than the smaller capacity models. Now, this may be relevant to your situation because it was quite common to fit 3 of each type - whether to 350 engines to counter slip, or to 450 engines to make the clutch more manageable ;).

In fact, I see Nigel still offers just such a combination for 350 race engines - or for "or those requiring a bit more pressure than the standard 250/350 setup" :) .

Go:
https://www.laceyducati.com/ducati-part ... lua0gmc4v2

P.s The slots in the screws are always chewed up. Dunno why - there's no need to go tough on them. As Bill says, just do them up normal, nice and even.

ducwiz
Posts: 604
Joined: Tue May 22, 2012 12:52 pm
Location: near Frankfurt, Germany

Re: Slippig clutch and valve liffter on a 350 scrambler.

Postby ducwiz » Sun Oct 13, 2019 12:53 pm

Conderning the valve lifter: imho you don't need one, if you know how to kickstart a thumper properly. And: the desmo singles do not have a lifter. The desmodromic valve control does not enable to apply the mechanism from the SCRs and MkIIIs. They have been kicked by all their owners ever since, anyway.
I rode my 350 Desmo >30Tkm, never missed a lifter. My achilles tendon was never hurt by a backfiring engine.

cheers Hans

Jacks the Lad
Posts: 36
Joined: Sun Oct 06, 2019 3:13 pm

Re: Slippig clutch and valve liffter on a 350 scrambler.

Postby Jacks the Lad » Sun Oct 13, 2019 4:11 pm

Thank you every one,
Yes, now it's been pointed out I can see the shorter springs are of a slightly heavier gauge. But when placed in their cups they barely stand proud of the pressure plate, so don't see that they are going to be much under compression once the retaining screws are done up. On the other hand the new set that came with the bike do stand proud, so I thought I might just, to satisfy my curiosity I would put it all back together and see what happened. Result, I can stand on the starter now. As I now have a puller and know how it all comes apart I plan to leave it alone and see how it goes (once it taxed that is).
I think I need that valve lifter even more now.

Jordan
Posts: 1380
Joined: Fri Dec 24, 2010 11:29 am

Re: Slippig clutch and valve liffter on a 350 scrambler.

Postby Jordan » Sun Oct 13, 2019 8:43 pm

British bikes used to have adjustable springs, that could compensate for a degree of spring shortening.
Similar effect can be had by fitting washers under the screw heads on Ducatis etc.
OK as long as the springs don't become coil bound on full lift.

Jordan
Posts: 1380
Joined: Fri Dec 24, 2010 11:29 am

Re: Slippig clutch and valve liffter on a 350 scrambler.

Postby Jordan » Sun Oct 13, 2019 8:49 pm

ducwiz wrote:Conderning the valve lifter: imho you don't need one


It's not really needed, but having swapped over my desmo head for a normal type with valve lifter, it's somewhat of a luxury in comparison.

blethermaskite
Posts: 477
Joined: Thu Mar 01, 2018 1:06 am
Location: northern ireland

Re: Slippig clutch and valve liffter on a 350 scrambler.

Postby blethermaskite » Mon Oct 14, 2019 1:00 pm

I was brought up on Velocette's and anyone who is familiar with that marque will know that once you master the art of starting a Velocette thruxton you will know how to start any 4 stroke single, you can stand on the kickstart of my 350 mk3 for a couple of minutes on compression before the engine will turn over, to clarify my earlier posting, the valve lifter in itself doesn't make the engine easier to start but it makes placing the piston in the optimum position on the 4 stroke cycle "for starting" easier.
Cheers,
George

Jacks the Lad
Posts: 36
Joined: Sun Oct 06, 2019 3:13 pm

Re: Slippig clutch and valve liffter on a 350 scrambler.

Postby Jacks the Lad » Mon Oct 14, 2019 2:30 pm

I know where you are coming from George, I too was brought on big singles, Velocette's included. However age and infirmity ( osteoarthritis ) is catching up with me which is why I would really like a valve lifter. Or even one to copy, a dimension drawing might do, looking at pictures in the spares book tells me what it looks like, but not the size of anything.

blethermaskite
Posts: 477
Joined: Thu Mar 01, 2018 1:06 am
Location: northern ireland

Re: Slippig clutch and valve liffter on a 350 scrambler.

Postby blethermaskite » Mon Oct 14, 2019 4:27 pm

There is one on Ebay at the minute in the U.S, but its a bit too expensive for what it is. put in Ducati valve lifter and have a look.
Cheers
George

Buster
Posts: 39
Joined: Fri Dec 22, 2017 12:56 am
Location: Reading, UK.

Re: Slippig clutch and valve liffter on a 350 scrambler.

Postby Buster » Tue Oct 15, 2019 8:29 am

There is the method used for starting a bike on rollers, back the bike up in gear until compression (in reverse) then your piston is in the same position as it would be if you used a valve lifter. A good swing on the kickstart with then give the flywheels the momentum to start the engine.


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