My M20 is finally running . But not all is well .Sadly.
I have rebuilt the gearbox, renewing all bearings and bushes, shimming it carefully ,
indexing it as good as I could . The internals were undamaged and in excellent condition. On the bench the box works beautifully . All gears engage easily and decisively . BUT : when I install the box in the bike 1st, neutral and 2nd engage wonderfully but 3 and 4 will not . Ever. I have removed , re -indexed and re -installed the box several times now but the result is the same each time. It works great on the bench but on the bike 1st , neutral and 2nd are easily found but 3 and 4 unobtainable .
Clutch ( 1 spring type) works fine too . No slip, no drag and operation is very light.
And yes, the gearshift lever is tight on it's spindle .
I did read the piece on indexing the box in the technical section by Ian Wright.
I do not know if my gearbox is somehow different but when peering in the inspection cover on the back of the box the face of the first gear pinion is almost completely obscured by the selector fork and the "ceiling" of the gearbox itself .This makes it nigh-on impossible to observe the gap between it and the dog teeth on the selector forks and thus obtain the desired "equal gaps ". Therefore I indexed mine by trial and error and , as said , it works great on the bench but not on the bike .
Any suggestions to help solve my this "mystery problem " would be greatly appreciated .
When rebuilding gear boxes, its very important to make sure all the many rings and shims are there AND on the right place.
Otherwise you will have difficulties changing gears.
If you are not sure, check the exploded view on Draganflys parts book.
Viewing the first gear engagement can be difficult. In neutral, if the 3rd/4th selector dog is central between it's respective gears use the gap there to gauge the gap between the 1st/2nd selector dog and the second gear. The distance between 1st and 2nd gears and 3rd and 4th gears should be the same.
