March 8, 20179 yr Not many of these to see these days but I have one that is misbehaving. Practicing a few weeks ago I lost the ability to shift gears. Didn't get banged. Lever resisting up a down movement on the spring but no selection. Thought the problem would be the locknut on the eccentric cam coming loose. But not the problem. Have stripped the mechanism in the primary case. Nothing seized and no broken springs. Moving through the range of adjustment allows a setting that will allow going up the box or down but not both. All gears select easily using the square 8mm peg. Timing marks lining up correctly. No noises from gearbox so I think it's the mechanism in the primary case. Any tricks anyone knows to solve this selection problem please?
March 8, 20179 yr Hi Stichillist I've just finished rebuilding one of these and the gearchange mechanism was one of a few areas of the bike that caused a fair bit of frustration (to put it politely)! One thing I found is that when you're setting up the gearchange mechanism and doing a static check to make sure all gears select correctly, you need to rotate both the clutch and the gearbox output sprocket (or the rear wheel if the chain is still attached) while you're doing it, due to the relatively large movement of the selector forks within the crancases. I did this as part of an engine build so it didn't have a top end at that point. As your engine is complete, you'll need to remove the spark plug to reduce the compression as you turn the engine over I'd recommend that you take all the external selector mechanism off, so you've just got the end of the gear selector drum staring at you through the oil seal in the L/H crankcase. Then use an 8mm open-ended spanner on the square of the drum and check you can select all 6 gears whilst rotating the clutch and gearbox output sprocket by hand. Once you know that all 6 gears select, you can then assemble the external selector mechanism and fine-tune it using the eccentric adjuster. It's a bit fiddly, but once you get it right it's actually quite satisfying. Keep us posted.... Gavin
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