Author Topic: dragonfly kick start jammed  (Read 4591 times)

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Offline DAVE NICHOLSON

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dragonfly kick start jammed
« on: 24 May 2012 at 18:50 »
it would appear that my kick start is jammed ,i can get gears ok  but kick start no good . Is there a simple solution or major strip of gear box , or could a solution please be forwarded to me as help is required , Yes i am a bit of a novice with mechanics  DAVE
« Last Edit: 28 May 2012 at 12:30 by DAVE NICHOLSON »

Offline eddie

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Re: dragonfly kick start jammed
« Reply #1 on: 31 May 2012 at 15:33 »
Hi Dave,
            When you say the kickstart is jammed - is there any movement of the lever before it jams?
      If there is no movement, then the kick start shaft itself is probably seized in the bush. To get at it, remove the shock absorber cover from the gearbox sprocket, then undo the 1/2" nut that retains the sprocket assembly (you may have to remove the screwed plug from the opposite side of the gearbox to access the other end of the bolt). With the sprocket removed, undo the 6 x 1/4"BSF nuts that secure the final drive housing. This can then be withdrawn complete with the final drive shaft and bevel gear. Through the aperture you can then work on the kickstart assembly.
     If there is some movement before it jams, then the problem is likely to be with the auxiliary shaft. This is in the bottom of the box and is supported by the auxiliary cover (the small round cover with three screws - just below the pivot of the swinging arm). The auxiliary shaft has a cross pin that locates in slots in the cover - any overloading results in the cover breaking at the root of the slot. This can lead to the gears jamming. I have never understood why Douglas went to the bother of stopping the shaft from turning - the 2 gears it carries are only in motion when the kickstart is operated, so negligible wear would occur if it was allowed to rotate, and the boss could be left solid and therefore much stronger.

     Regards,
                   Eddie.

Offline DAVE NICHOLSON

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Re: dragonfly kick start jammed
« Reply #2 on: 31 May 2012 at 19:15 »
Many thanks for your info. The first thing  i looked at was the auxiliary shaft seemed ok . I then rotated the engine through the bell housing a few times to find the kick start was sort of working only to jam again with no movement but with a little extra pressure it freed its self . Have tried it again today seems ok but does not feel right .The engine is out of the frame at present ,look forward to any other thoughts on the problem or do i strip it down to have a good look, DAVE NICHOLSON

Offline eddie

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Re: dragonfly kick start jammed
« Reply #3 on: 31 May 2012 at 20:35 »
Dave,
        It sounds as if the kickstart ratchet may be binding. The ratchet itself is mounted on a sleeve on the rear end of the layshaft. Now, it is possible to overtighten the layshaft nut, causing the sleeve to swell and grip the inside of the ratchet, thus causing the engine to drag the kick start round to the end of it's travel. As before, this can be attended to, working through the final drive aperture.

      Regards,
                   Eddie.

Offline DAVE NICHOLSON

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Re: dragonfly kick start jammed
« Reply #4 on: 02 Jun 2012 at 10:28 »
Eddie ,have done all of what you suggested , lay shaft spins ok no snagging ,auxiliary shaft sits in slotted cover ok  . I have then used the kick start as usual by hand so as not to put to much pressure on both shafts all was ok . Went for a coffee and tried it again  kick start solid  ,spun the engine from bell housing end and all was ok again. The kick start works well  but then as i say it suddenly stops ??. Can find nothing wrong with the mechanism any thoughts DAVE NICHOLSON

Offline eddie

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Re: dragonfly kick start jammed
« Reply #5 on: 02 Jun 2012 at 10:58 »
Dave,
         Check the timing of the kickstart gears. The kickstart drives through a pair of bevel gears - the small gear has 4 dogs which connect it to a large gear with a missing segment. With the kickstart lever in the raised position, the missing segment should be facing the gear on the tail end of the layshaft - that is, not driving the layshaft when the kickstart lever is at rest. You should be able to retime it by either remeshing the bevel gears or by turning the small bevel gear to the next dog, or both. If this doesn't improve matters, have a look at the gear with the missing segment - if the leading tooth is bruised or flattened, it may not be falling into mesh with the layshaft gear - but, instead jamming crest to crest with it. If this is the case, try grinding a little from the leading edge of the tooth - this will improve the engagement.

    Regards,
                Eddie.

Offline DAVE NICHOLSON

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Re: dragonfly kick start jammed
« Reply #6 on: 02 Jun 2012 at 13:43 »
Eddie, have now had a good look at the meshing of gears on auxiliary shaft and lay shaft it appears the dont line up correctly , would this be that they are to worn. They appear in one place that we are getting almost point to point on the gears . Would this mean getting new gears to resolve the problem. DAVE NICHOLSON

Offline eddie

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Re: dragonfly kick start jammed
« Reply #7 on: 02 Jun 2012 at 14:58 »
Dave,
        The teeth on the 2 gears are probably not that worn - they are not of the normal involute tooth form - they are very pointed to aid engagement. You say they do not seem to line up - this may be so - the gear on the tail end of the layshaft moves axially as the ratchet operates, but they may be further out of line than was intended. Have you got a spacer washer on the auxiliary shaft behind the large gear? - I have just looked inside my spare gearbox and there is a hardened spacer 40 thou thick. Without it, the large gear could be pushed forward by the mesh of the bevel gears, causing it to foul on the flange at the front of the ratchet gear (especially if the ratchet has not dropped fully into place) - thus preventing the kickstart from turning. This would account for the occasional operation of the kickstart.

          Eddie.

Offline DAVE NICHOLSON

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Re: dragonfly kick start jammed
« Reply #8 on: 02 Jun 2012 at 15:12 »
eddie i think i have found the problem . The housing the auxiliary shaft sits in at the back of the gear box has cracked and a piece has come out thus allowing the shaft to float about . So its looking like a new gearbox shell i suppose  DAVENICHOLSON

 

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