Trying to start, sounds clacky (audio)

Ok... I just found this online. I think I finally get what's going on...


Although, in our case I don't think it is back rotation we are worried about. I think what happens is that once the engine starts it is turning more quickly than the starter clutch...

Ahh, that makes sense, so it's called a trapped roller clutch. That's an interesting way to make a one way clutch, thanks Under Dog for the video!

Understanding the mechanism helps me understand where to look for wear and other failures.

Great video

Just wanted to follow up. I got the springs out and compared them to what was available at McMaster. I think that the springs I got are still a little too stiff compared to the original, but the good news is that it works great. I'll update later today with the specs on the springs. I measured the spring rate, length, OD, wire diameter and number of coils of the original spring.

I found this spring on Century Spring that I think would be an ideal replacement, but the $40 minimum negated any savings. I might run the stiffer spring for a short while, then rip it back open to see if there's unnecessary wear on any parts due to the stiffer springs. (The spring I used from McMaster is about 3 times firmer than my measurements of the old spring, which I assume has lost some firmness over time).


Good news is, the bike starter works great and for the first time ever, the bike has started!

Good deal

I've got to imagine that as long as you were close to the original size springs, you'll be ok. My starter clutch is next on my list. Fortunately, I've found NOS parts just down the road for a reasonable price.

Glad you got it fixed!

How about this issue, my starter works fine when cold, but when hot it turns the engine over once then slips. Maybe just a broken or weak springs? Gotta take that side of the engine apart anyway to troubleshoot a weak charging system (maybe nothing wrong with it, manual says you should have over 14 volts at 2500rpm, I don't but all my electrics work and the battery stays charged)

Sound like the starter clutch is worn. The bike should charge 14.5-7 volts at 5k rpm.

I recall looking at diagrams for the roller locking bolt on an HK MP5, and saw it's the same principle. The roller locks itself in place due to the centrifugal force, so the bolt and barrel are essentially "Clutched" together long enough that each shot fired is coming out of a single unit, using nothing more than a few roller bearings and some redirected force.

Physics. Making nature it's bitch since forever.

Hi guys,

This is my first post, I have a 1980 with this same problem but all the starter clutch replacement kits I've seen are for an '82 and newer. I emailed mikes Xs and the reply was "no sorry the '82 won't fit an '80" so now I'm trying to figure out where to get a kit! I'm sure someone else on here has the same predicament as me. Any advice would be greatly appreciated.

Cheers!