My '06 RSVR-F's just made me a member of this thread.
With a fully-charged battery, the first start of the day (of this track-only bike) results in a resounding 'click' from the solenoid, but nothing else. This has happened for both of my two venues this year.
Jumping it from my car makes for no improvement, so I decided to short the solenoid high-current terminals and hey presto, the engine springs into life. For the rest of the venue, there's no problem with the starter... it springs into life first press of the button. Then next time out, we're back to square one.
These symptoms suggest to me that:
- the battery's okay;
- the starter button is okay;
- the starter motor is okay;
- the sprag's okay.
Looks like I'm up for the Yamaha 4KD-81940-00 part.
As I'm on my second solenoid now, I just had to strip one to find out what makes it tick (pun intended).
Here's the full set of parts.
When the solenoid is OFF, the moving plunger (silver) is pushed up (to the left in this pic) by the spring on its right. This pushes the high-current contact bridge (copper, centre) clear of the high-current terminals (copper).
When the solenoid is on, the winding in the base pulls the plunger down (right) against its spring and the spring to the left of the bridge pushes the bridge down to make contact with the terminals.
Here's a close-up of the bridge and the terminals:
There are two pits where the contact has been made.
I would guess that, when made, the solenoid is closed in a relatively inert atmosphere (nitrogen?) to reduce the formation of compounds on the contact surfaces.