My starter sometimes starts my CF625, and sometimes it just spins without engaging. I replaced the starter, same problem. I opened up the engine where the starter gears are, and everything looks great to me. No broken teeth, everything clean, no obvious (at least to me) signs of wear, gear teeth engaging and turning as expected. The overriding clutch appears to be working just fine. It turns freely in one direction, but locks up and won't turn -- at least not by hand -- in the other direction. Yet the only thing I can think that would allow the starter to spin without engaging/cranking the engine would be a bad overriding clutch. Is it common (or even possible) for the overriding clutch to be faulty, so it sometimes doesn't lock up and allows the starter to spin? If I replace it, should I also replace the driven gear that the overriding clutch locks onto and turns, just in case there is enough wear-down on it to reduce the reliability of the overriding clutch locking on to it? Thanks in advance for any help on this!

My first step would be to replace the sprag (what you call overriding) clutch. Sounds like it's working intermittently.

[2015 Z Force 800 53/Trail EPS]

It is common for the overriding clutch to develop flat spots on the contact areas of the straggs and allow it to slip under load. It is also been "suggested" that this may be a side effect of running synthetic oils they just do it's job so well it maintains too much of a film between the two points and allows slipping to begin. No proof though.. but it is odd that the highest number of these failures are in engines running synthetic oils. I also run synthetic and when cold mine also tends to slip sometimes. Replace it.

Thank you both for the quick replies. I will go ahead and replace the overriding clutch. I'll also take a closer look at the driven gear for wear, and replace it if wear is noticeable. Even though I'd rather not spend the money, time is money, and I'd rather not open everything up again later to try to fix it again if the problem persists.

I replaced the overriding clutch, put everything back together, and happily my CFMoto now starts every time (at least a dozen starts in a row without any slippage at all). Thanks again for the help!

[2015 Z Force 800 53/Trail EPS]

I replaced the overriding clutch, put everything back together, and happily my CFMoto now starts every time (at least a dozen starts in a row without any slippage at all). Thanks again for the help!

Save your starts...every one used is one less then you will have.. as every one wears just a little. And because of the overall quality of Chinese metal, you will get something less then half as many as you would with Japanese or North American-made. Plus if you didn't also replace what the spragg locks against, because it will also be warn, even less then that. So save them...lol     

...and here automakers are adopting a system where any time you come to a stop the motor shuts itself off and restarts when you push on the gas pedal, like a golf cart! Starter cycles have just increased more than 10 fold overnight. 

[2015 Z Force 800 53/Trail EPS]

...and here automakers are adopting a system where any time you come to a stop the motor shuts itself off and restarts when you push on the gas pedal, like a golf cart! Starter cycles have just increased more than 10 fold overnight. 

No Sh*t? Wonder if charging systems can keep up with all that battery draw.