Starting problem

[Mark Prett]

Hi everyone,This is my first post here.
I have a 2011 (51 plate) Ex-Police R1200RT that I use to commute.It has developed a problem starting when the engine is warm, if left to cool it starts fine (a problem when stopping for fuel).The ignition turns the starter motor but it doesn't seem to engage.
Any ideas?

[David.]

Is there any difference in the measured battery voltage during starting cold vs starting hot.

[Mark Prett]

I don't have the means to check that, but the battery is brand new and the starter seems to turn strongly.

[David.]

Does the starter motor turn at the same strength whether the engine is cold or hot.

[Mark Prett]

Yes it does.
When cool the engine starts in around 1-2 seconds

[David.]

The ignition turns the starter motor but it doesn't seem to engage.

This video shows a starter motor failure & replacement, https://www.youtube.com/watch?v=NSTfZaEERCc
Fast forward to 8:50, it can be seen that the Bendix drive pinion is sliding forwards to engage but not turning.
At 11:50, a new starter motor can be seen to slide and spin at the same time.
When the new starter motor is being fitted, you can see where the Bendix gear should engage with the clutch flywheel.

If things are ok when cold, I wonder if heat from the engine is having some effect on the starter motor.

[Mark Prett]

Will look at the video this evening.
Thanks.