Gearbox issues Z1 750

[Ian Hand]

I am hoping someone here can offer some advice on the kick starter problems I am having with both my bikes.   The kick starter pedal slips out of engagement almost every time it's pressed. The bikes start first kick if the ratchet engages and stays engaged for the entire stroke of the pedal. If it slips, then the pedal only has half travel before it reaches the stop. That amount of travel is insufficient to roll it over any more that 1-1/2 revolutions.  So starting become a matter of luck.
 I believe the gearbox is the same on a number of late 20's and early 30's bike so someone else may have solved this problem (if it is a problem and not faulty assembly on my part)  I look forward to some discussion on this as I would like to fix it before the next Annual Douglas gathering in QLD 2025.

[Doug]

Ian,

The Zed models ought to have the final iteration of the 4-speed kicks start mechanism. Introduced in 1934 and carried through to the end of the 600 Aero model. That uses a Bendix scroll. If that has oil on it, it can get sticky and fail to engage fully De-grease and use a dry graphite lube on the multi-start threads. Do put some grease on the post.

It action relies upon spinning along the multi-start thread and forcing the face dogs into mesh before the entire Bendix starts rotating on its post. 

-Doug

[Ian Hand]

Thanks Doug, I will pull the gearbox out before the next Douglas gathering and see if the bendix is operating freely.  There is no oil in that part of the gearbox so it could be the problem. The bike does not get a lot of use. 

[Doug]

No need to pull the gearbox out of the bike to get to the Bendix, just remove the outer end cover. There should be no oil in the end cover, just a little amount of grease on the kickstart gear teeth.