And Another One (Sprag) Bites the Dust

The sprag on my grandson's Mk3 finally gave out. Fortunately, I have a new sprag and good used Mk3 parts on hand, so it should be up and running again in the next few days. More teardown planned later today. We had removed the kick starter previously. The return spring had failed, and we didn't think it was worth the effort to pull the cover and repair it at that time. But we will fix it while we're at it this time.





Ken

Ken, was this an original sprag?
Im still running a $17 Alibaba sprag from a few years back.
It seems to have a better angle of attack than the expensive Norvil sprag had. That one was nearly over centered just as it started to turn the crank. After a day or so it did flip and destroy itself.

Glen

Hi Ken: In your picture I can see that the nut for the peg on the foot rest is to the inside. If you use a half/jam nut on the other side of the footrest holder, then you can cut off the extra length of the foot peg and gain some clearance between it and the primary chain cover. This helps to keep the cover from being gouged with a minor tip over or side bump by the nut.
Yep, I learned the hard way.

franko said:

In your picture I can see that the nut for the peg on the foot rest is to the inside. If you use a half/jam nut on the other side of the footrest holder, then you can cut off the extra length of the foot peg and gain some clearance between it and the primary chain cover. This helps to keep the cover from being gouged with a minor tip over or side bump by the nut.

Click to expand...

The 850 Mk3 (as it is) footpeg, however, has a shorter thread and a taper so fitting a jam nut on the outside of the footrest hanger isn't possible (without modification).

Thanks LAB, I didn't know about the change.

worntorn said:

Ken, was this an original sprag?
Im still running a $17 Alibaba sprag from a few years back.
It seems to have a better angle of attack than the expensive Norvil sprag had. That one was nearly over centered just as it started to turn the crank. After a day or so it did flip and destroy itself.

Glen

Click to expand...

I believe it was original, Glen, but can't be sure. I bought the bike as a basket case, so don't have any of the prior history.

The new sprag we fitted yesterday was also one of two I bought through Alibaba a few years ago.

Ken

Pulled it apart yesterday. Picture below shows sprag damage. The surfaces the sprag bears against on the sprocket and starter gear were both sereiously dented, so we replaced both with a good used pair. Should be together and running again this week. While it's apart, I'm also going to check out the clutch stack height again. It's been slipping under full throttle acceleration, which is particularly annoying when trying to get up to traffic speed on highway on-ramps. We're also planning to repair the kick starter mechanism and re-install the kick start lever. We've been putting that off because it requires disconnecting and removing part of the Comstock hydraulic clutch mechanism, but it now seems worth the effort.

Sorry, no pictures. I don't appear to be able to add any pictures. I'll see what I can do later.

Edit - Duh, let my VIP membership lapse. Just renewed it, and added picture.



Ken

Had my starter drive gear modified by the excellent Mr Shand to provide a much harder surface to head off that wear...... Also closed the working gap a fraction, IIRC....