I have successfully removed both the crankshaft end nut and the flywheel / starter clutch.
The crankshaft end nut was removed by inserting a 2p which jammed against the starter ring gear and the crankcase at the top, with the bike in gear and back brake on. The flex from the cush drive makes it too squishy for an impact driver to work. i found that the starter ring gear can be locked to the flywheel by inserting m10 studding so that it goes through one of the threaded holes in the rotor to locate in a ring gear hole. i used a breaker bar with success.
I used a snap on rotor puller and a breaker bar to remove the rotor.
once again a 2p coin was used to lock the rotor up solid as it wanted to turn with the puller. No heat was employed, just when i thought the rotor wasn't going to budge, it flew of the end of the crankshaft, taking the starter clutch parts with it.
On inspection, I find that the starter clutch parts i had purchased secondhand to do this job are , quite simply, wrong.
The starter clutch bearing on my IVJ has S shaped 'teeth',
whereas the spare I have is a different size, and has oval 'teeth'
looking at parts listings, the spare appeasr to be from a 3tB engine.
Non interchangeable, I am guessing.

3tb

IVJ
I have contacted Fowlers for a replacement starter clutch bearing
for the IVJ, and they tell me it is now discontinued.
Be very interested to hear from anyone who has successfully replaced or repaired the starter clutch on an IVJ, or any leads on getting a replacement bearing.
There is a rumour floating around on these boards that the IVJ bearing may be repaired by disassembling and turning round the S shaped teeth.
Can anyone confirm the validity of this rumour ?
The 3TB bearing ( made by Morse ) could, conceivably, be repaired by shortening the spring that surrounds the pawls (?)
Sprag Bearing
The IVJ bearing is marked NW ( a bearing manufacturer ) and then what could be 0M or OM or GM or 6M