The starter motor on the 650 variants (e.g. CX650 and GL650) can seem tired at times, and it’s not just the sprag clutch that has issues – the starter motor itself doesn’t have the best grounding setup internally. To the best of my knowledge Hans (ofapars) was the first to do this and there have been a few good writeups of it since with different approaches. We’re currently looking at two of them, but first the reasoning behind it.
The plate which holds the brushes/springs/etc. inside the starter motor has three raised tangs which contact matching pieces on the end piece of the starter motor, providing continuity to ground:
In practice the contact isn’t great and you end up with arcing and subsequent pitting:
Having a dodgy ground isn’t going to help your starter motor at all, and over time it will just get worse. The solution? Improve the route to earth. As a further point, it’s also worth checking to see whether someone has over-tightened the outer nuts (or tried to loosen a stuck nut) and twisted the main power terminal, causing damage internally. Fortunately all of the motors we have had in-house have looked like this:
…but worth checking.
There’s four different approaches that we have seen to this solution:
- Solid metal bar joining plate + end cap, bolt through from outside
- Thick wire joining plate + end cap
- Drill blind hole into end cap from inside, tap and screw brush directly to end cap
- Drill hole through end cap, rivet brush directly to end cap
We’ll be looking at the last two currently. This mod makes the biggest difference for the 650s, but it’s not going to hurt your 500’s chance of starting!