Sprint 2010 St Starting Issue

Have you done anything to the bike, since it last functioned correctly?

I had similar with mine recently, fault turned out to be me. I trapped & shorted a wire, when fitting crash bars.

 

There can be several causes, but commonly, it is pitting and carbon build on the contacts, caused by either rapid and excessive activation, or insufficient battery current. N.B. The battery may have full voltage, but an internal defect, may cause low current. That is the same effect, for both the solenoid and the relay.

The starter relay, removes power to the headlights, whilst the starter is operated, to enable the battery to give its maximum output, to the starter motor. Common advice, is that if you hear a click, then the solenoid is good, however, that is not an absolute. A bench test will give an absolute.

Both the solenoid and relay are easy to remove and bench test. If they test as good, next I would conduct a load test on the battery. After that, would be connections and wire integrity, for which a circuit diagram is a must. A Haynes manual is normally a good investment.

Hope that helps in some way.

 

When I was looking earlier this year, I found a google listing which sold refurbished starter motors. I also found on eBay both salvage units from breakers and kits to do your own refurb.
Typically, salvage was around £80, and refurb kit around £40.
Doing your own change out of the starter motor is quite straight forwards. In the end, mine was ok. Had replacement been needed, I’d have gone salvage, in the first instance.
Hope you get a solution.