It worked! Shifting is better than ever before. My four-speed Royal Enfield with left-side shift linkage now moves cleanly between gears and even downshifts without missing gears.
There's a good reason for my delay in writing, and it felt like this:
Of course you couldn't really hear the clunk while riding, but that is what it felt like, a real disappointment after my initial efforts to improve things. If you've forgotten where this started, way back in December, here's a link to Part 1 of my campaign to improve shifting action.
Now, pulling over and inserting my head beneath the motorcycle I saw that the left-shift linkage I'd tried so hard to rebuild and improve was striking the frame of the motorcycle as it reached to activate second gear.
Not always: sometimes the linkage made it to second gear and, when it did, everything was wonderful. I could even downshift reliably.
That had been my goal. The linkage had been loose and wobbly and I had straightened and tightened it and removed places where it bumped into other bits of the motorcycle. It should now be near perfect and, yet, every so often:
"CLUNK!" And it got stuck with only first gear and neutral available.
With my head under the motorcycle I could see the the linkage wasn't just brushing the frame. It was ramming it.
|Arrow points to linkage arm contact on motorcycle frame.|
The obvious solution seemed to be to rotate the linkage slightly clockwise where it attaches to the shaft that carries shifting from the gearbox, on the right, to the left side of the motorcycle.
I tried. I couldn't do it. The upper arm of the linkage contacts something (the front sprocket?) that prevents it from being relocated. (Remember, the linkage is so hidden behind the primary drive cases that most adjustments must be done by feel or by removing the linkage entirely — I couldn't see what was blocking me.)
Let me tell you, ladies and gentlemen, as far as this linkage goes, there is very little extra room in the original design of the motorcycle — designed to shift on the right — for this added bit of mechanical mayhem to move shifting to the left.
|Linkage arm hits the frame at this point (arrow).|
|Linkage arm smoothed (at arrow) to eliminate contact point.|
(I also filed down the flange of the brass bushing to prevent it contacting frame.)
Here's my prescription, with explanatory links, for fixing the left-shift linkage of four-speed Royal Enfield Bullets:
1. Tighten up the gearshift lever.
2. Replace nylon linkage bushings with metal bushings.
3. Tighten linkage attachment to the gearbox shaft.
4. Eliminate interference with the linkage movement.