The previous owner renewed the sprag clutch but the mileage and number of starts of the bike when in his possession must have been absolute minimal as it's life consisted of starting up a few times a year, 2k miles of short runs in 20yrs. I have reason to believe the sprag needs replacing again - starting problems with the occasional machine gun noise. So my question is what can cause such premature failure? Are these things as fragile as the forums have us believe?. Are they really made from Parmesan Cheese?
low mileage/premature failure could be down to several reasons and hopefully some owners will add some casebook history. The main reason for early failure that comes to mind is down to repetitive attempts at starting combined with slow churning.
the replacement procedure for many later bikes can be found on YouTube but I should think yours, although similar may have a slightly different approach. couldn't find the part numbers on a quick glance but a hunt equipped with these could get the price down, you often need all 3 items unfortunately but careful inspection of mating faces will confirm https://ducati-gowanloch.com/shop/engine-parts/ducati-starter-sprag-kit-bevel/ http://forum.bevelheaven.com/viewtopic.php?t=4542 EDIT - Sprag itself might be SKF 445419 ?
As Chris says, a tired battery is a sprag-shagger (paraphrasing). Best to fully charge the battery before attempting the starting procedure after not running the bike for a while. However, once you have the sprag out of the bike, I'd take it to a bearing supplier, they'll be able to match and source a replacement bearing (sprag) surprisingly reasonably (I paid 30 quid for the last one I bought), they'll probably also be able to advise on which offering might offer best quality. Good luck
Before diving in and replacing your sprag clutch, I would get a Yuasa AGM battery from Halfords with your subscribers trade card and order a starting circuit cable kit from @Exige, with your subscribers discount and then see where you are with the sprag clutch. Imho, it may work ok with a bit of energy behind it.
The flange and starter gear should be replaced at the same time. If this didnt happen previously, it may have sped up deterioration of the new sprag. The starter gear could have some wear which isnt helping.
While reading up on above I see owners have cited backfiring as causing sprag clutch failure. Have had several big backfires while attempting to start but no apparent change to starting or churning afterwards as a result but I have got a clutch assembly in my spares with a severely distorted frame. I couldn’t work out how this could’ve happened so this may account for it.
Aha, I thought I didn't recognise SD as a model number, just presumed it was some kind of typo. My Bevel, a 450 Desmo I had in the late 70s, was very much a kickstart machine and tried to take your leg off every time...
Thanks all. Battery is new and on trickle charger permanently. One bad earth found which could have been the owners problem - little grey wire from under fuse-box housing to frame. Without it, little or no sparks... Strange, in the 30 odd thou miles and 15 odd years I owned it before I didn't even know what a sprag bearing was. So one step at a time: Take out the new oil I just put in after having the clutch cover off to free up stuck clutch plates...merde, then full inspection of sprag and area. I have stopped trying to start it after hearing the racket the sprag makes when not picking up, 'kin 'ell.
Just a follow-on re the loose earth in case I have misled... The wire in question is Grey/Green - and - while in that area (fusebox etc) I rotated the fuses several times in their mounts to make sure of good connections so I can't say for certain the loose earth was the cause (of no sparks). I have a new fuse-box to put in as the cover is missing from the original but that looks like a winter project to change that over - not the easiest of access
Well, I have sharply tapped the flywheel opposite the keyway. I have heated it all with a hot air blower and hit again and the flywheel has not “just popped off” as it should using this method, merde. Proper puller appears only available from US or Oz at great expense so before I bite the bullet any more tips for getting the flywheel off before I miss-cue and hole the crankcase with a sledge
“It’s Off” , popped off the 3rd hit. Seems very brutal but thanks Derek for giving me the courage of my own convictions. I rested the flat face of a med size ball-pane on the rim then gave a the dome face of the ball-pane a good clout with a lump hammer. Moved round a bit, repeated and Presto. Thanks again
