I've been doing a lot of reading about St4s starting issues and have worked my way through all of them! My bike is a 2002 ST4s with 40000 miles on the clock. Mine started (?) with the solenoid sticking on. This is quite stressful because you can't turn it off even if you turn the ignition off. If you don't notice, it is possible to go out for a drive with the starter motor running and not notice until you stop and turn the ignition off at which point the starter carries on turning the engine over until the battery gives up.... I replaced the solenoid but starting was still very sluggish, I reckon because the motor brushes were shot as a result of the above. I replaced them with an OEM Ducati kit off e bay. To do this you have to take the LHS part of the engine off, However, unless you are doing the sprag clutch, you dont have to take the flywheel off, so I did not, although I did think about it. Shortly after putting it back together, the starter (which was now working very well!) began to do the sprag clutch freewheel thing. So, i've got it all in bits again, only some 40 miles after having put it all back together from the starter rebuild. I should point out that most of the photos and videos showing sprag clutch renewal do not show the one specific to the ST4s, ie the one in which you have to remove all those allen bolts in the centre of the flywheel to get the sprag clutch out. The one on the st has a collar on the lower plate which sandwiches it between the flywheel and the bit which holds the clutch in place. If you follow the videos on e bay you will be removing the circlip on top of the sprag until the whole thing falls apart, at which point you realise that to get the clutch out, you don't have to remove any circlips, merely undo the bolts in the flywheel. So, i've ordered one of these sprag clutches from China. They are on e bay and cost between £40 and £56 dependent on the application, I have gone for the £39.95 option since it has the collar and matches up to part no 701.4.007.1a. Has anyone got any experience of these sprag clutches, if so would you like to share it with us, positive or negative? I know, I know the poor man always shops twice, but maybe if OEM parts only last 40000 miles or less, I've got nothing to lose.?
I changed the starter brushes on my wifes ST and the £3.95 end plate with brushes can be fitted without taking anything off the engine. Okay it is fiddly but it can be done from the back of the starter. Made a huge amount of difference to starting.
Ive just bought a 10quid SKF seal which has the spring which is the part that goes, couldve saved yourself a bit. The KTM sprags are about the same price as that Chinese one too iirc. Im gonna start with a brush kit first as I think it could be my starter thats goosed.
hi levoz sprag spring only works one way so mark your old one with tipp ex ,before you remove it and clean and lub every thing on rebuild let hope the working faces are fine make a card board gasket then mark around the edge no 1/12 as not all the screws are the same lenght but you know that as you have been in there before mike
