Belt drive for Mk3 that retains starter belt to run in oil

Previously stuart_glynn wrote:

Does anyone supply a belt drive with clutch for Mk3 retaining starter?

There is a need for oil to lube crossover gear/lever as the bush is drilled and scrolled for lube and also there are sprag and other starter gears that might need some lube so I do not want to consider a dry primary if keeping starter.

I know Tony Haywards belts can run dry or in oil and expect others too.

The other thing to consider is the gearbox is fixed on Mk3 so no adjustment.

Any suggestions welcome.

The crossover shaft will run fine with little grease. The sprag is the problem. I don't think there is a belt drive out that can accommodate the sprag. I'm sure it's the drive pulley that cannot be modified to accept it.

Why the upheaval, the chain is perfectly suitable and should last over 50K miles easily.

Of the one Norton that broke down, that I know of, on the way back from the International rally this year it was due to a belt.

On the race track yes, but on the road for a MK3, not worth the bother.

As well as the breakdown that Ashley mentions on the way back from Austria there was a blue commando stood for a few days at the rally site, primary drive in bits, tools etc just left there and a broken drive belt on show for all to see. If you do go down the belt route, carry a spare!

Otherwise stick with a chain (duplex) No one makes decent triplex anymore.

+1 On the road for a MK3, really not worth the bother!

Previously peter_shand wrote:

As well as the breakdown that Ashley mentions on the way back from Austria there was a blue commando stood for a few days at the rally site, primary drive in bits, tools etc just left there and a broken drive belt on show for all to see. If you do go down the belt route, carry a spare!

Otherwise stick with a chain (duplex) No one makes decent triplex anymore.

+1 On the road for a MK3, really not worth the bother!

Not quite, quality triplex chain is available, I have just fitted a nice IWIS triplex chain on my MK3. Not sure why the IWIS duplex chain was so popular when IWIS triplex was available.

I have examples of the Duplex and Triplex Iwis, the Duplex is a work of art with the largest pins possible and the best materials, Triplex looks good like an OEM Reynolds from back in the day they made proper chains but the Duplex is better. The Iwis triplex will never be fitted while the Duplex is available on my bikes. I also use it in simplex form for the timing chain, no need to adjust tension after 500 miles, pre stretched out of the box. Also use it in a T120R.

Another option is to fit two simplex chains on the outer sets of teeth; a configuration Laverda successfully employed on the RGS and SFC1000, which have considerably higher, albeit smoother (120 degree crank) power output. With this set-up,the Mk3 tensioner plungers would remain equally loaded. A pair of IWIS large diameter pin chains would provide strength and resistance to stretching. I am considering this option for my Mk3 when it goes together, if a decent triplex chain is not available when I get to that stage (still some way off).

Andy

Stuart Glynn

The sprag assembly definitely needs good lubrication if you use the e start and it would be a good idea to use an oil type belt drive, with bespoke adjuster if necessary.

John Holmes

I,m in the process of changing to Iwis Duplex so good to hear your positive comments.

I removed the Mk3 tensioners long ago and successfully fitted a Harley Sportster manual adjuster.

The Duplex is indeed a work of art next to the CZ Triplex and is also around 13oz lighter overall with the third row of teeth ground off the sprockets.