Parilla Motorcycles

Parilla Clutch Conversion

Jim Avery has been working on this project for quite some time. He has managed to finally work out the small problems associated with such a conversion. The original Parilla clutch is a combination of increasingly hard to obtain parts. The solution Jim has trying to work out is grafting a reliable Yamaha clutch to the Parilla innards. This has all been done to keep Parillas on the road and improve reliability. Here is the rundown on the project:


1. - Original Parilla main shaft with no modifications.

2. - This is the inner clutch plate and race for the clutch basket and gear. The plate was machined out.

3. - Original Parilla needle bearings with no modifications.

4. - The clutch hub and gear. Ears have been machined off and holes drilled for mounting the Yamaha clutch basket.

5. - The Yamaha clutch basket with ears removed off the back and the center machine out.

6. - Hardened, tapered flat head 5mm allen bolts with nylocks. Used for mounting the basket to the gear.

7. - The inner Yamaha clutch hub with a new matching spline machined in by EDM.

8. - Spacer and left handed nut for attaching the hub to the shaft. This was made from scratch.

9. - The Yamaha clutch plates with no modifications.

10. - The Yamaha clutch outer. The inner part machined out and drilled to mount the new adapter spacer (#12).

11. - The original Yamaha clutch springs and bolts.

12. - The adapter spacer for clutch rod to push against. The shaft stuck out too far for the original to work. This was made from scratch.

13. - The Yamaha clutch shaft, rod with adjuster and push plate. No modification.

14. - Allen bolts and nuts to mount adapter plate (#12) to the Yamaha outer plate (#10).

A couple of minor changes were made since the above picture was taken. Part #12 was remade because it was hitting the outside cover when the clutch was disengaged. The new one is slightly thinner and a thrust washer is been used between parts #5 and #7.


The motor is not in the bike yet, but it is complete with Fairbanks magneto. It seems that it is going to work great as the lever works smoothly and easily. It seems to disengage completely and hooks up great. If part number 4 (the gear) can be made, then retrofit kits could be made without reworking the original Parilla parts. Dependability of the EDM machined spline on part #7 may be a problem, but can be resolved at a later time.

Here is the finished product with a twin plug modification.