I dont have any knowledge of motorcycle crankshafts and the last crankshaft taper I removed a flywheel from was a on  a Mini in the 1960’s. Depending how damaged or scored the surfaces are you might get away with dressing with very fine file or diamond hone and making a conical shim from brass to make up any loss of position.

If the damage is bad you could clean up the taper in the lathe and do the same with the flywheel bore, then make a bush with an internal and external tapers to get the correct axial flywheel position.

I used the shim method to mount a wheel hub on an axle shaft (about 25mm diameter) and is lasted 50 years and been assembled, disassembled several times.

Ian P

I’d be tempted to contact Alpha Bearings, as they specialise in crankshaft repairs.
They did my 900GTS big ends last year, though I’ve not had chance to reassemble it yet.

Bill

Probably worth at least investigating a ‘proper’ repair, isn’t it?

I’d ask on a Ducati forum – there are always people out there who know where to these things done..

Well Colin,

this is a bit of a coincidence. I’ve just stripped my 450 Ducati Scrambler and have the same problem with a taper that looks like a ploughed field. I stripped the engine last week expecting to find a blown big end. Instead, I found the magneto flywheel happily spinning free on the taper – so no worries about getting it off at least. As it happens, I had three different Ducati flywheel extractors, none of which fitted the motoplat magneto which I think like yours was retro fitted (in my case to upgrade from 6v to 12v).

I’ve lent the crank and side cover to GB Motorcycle Products for them to fabricate a crank turning tool as I’m the Tool Hire Secretary for the Ducati Owners Club GB and help them out with various Ducati tool designs when I can. When I get it back in the next few days I’m going to explore having the taper built up again and then reground back to its correct size. Although, as others have said, Loctite will have a suitable product to glue it back on (I’m also an ex-Henkle employee but not on the Loctite side unfortunately) I would prefer to do a ‘proper’ repair – grovelling apologies to my past fellow employees!

I’m happy to let you know how things progress either through this thread or you can PM me if you prefer.

One final comment, a number of suppliers of classic Ducati parts have either retired or are about to retire, so we need to move quickly to get these repairs done while consumables like gaskets, shims and lock washers are still readily available. This is what prompted me to finally strip my engine after leaving it languishing in the naughty corner for many years.

regards

Graham

On 15 March 2024 at 14:45 duncan webster 1 Said:

Surely it takes less torque to start the engine than the engine produces when it is running

Please could we talk through what you have written as I am not sure it is relevant.

On starting, the starter motor drives the ‘alternator flywheel’ so the ‘flywheel’ transmits the starter motor torque into the crank (via the dodgy taper).

When running, the ‘alternator flywheel’ drives nothing. The only ‘torque’ it will see is from the magnetic resistance (I do not know if that the correct terminology) of it being an alternator.

The torque of the engine is transferred from the crank to the drivetrain via the clutch basket, usually on the other end of the crank to the alternator.

Done an old vitage crank like that and I machined the crank down and lefthand screwcut the crank(DOR comes into play here) screwcut a sleeve , fitted with HS Loctite and remachined the taper, its still running today although not very often.

any recommendations on the best way to set the endfloat on the crank when I replace it?

I must confess I don’t know. The engine was rebuilt by Tony Brancato many years ago and I’ve never had to do one myself. Tony is pretty much retired now as far as I’m aware. However, Nigel Lacey who supplied your gaskets has a lot of experience with these engines and would be a good person to ask.

Graham