Kichstart jump with mod

[Geordie]

Having a problem with the kick-start lever jumping, I used a paddock starter until I could get hold of the parts for the coil spring upgrade. I have fitted the upgrade now but still have the lever occasionally jumping - even with the spark-plug out. I have stripped it down to attempt a diagnosis but cannot see the fault. I assume the jumping occurs at the ratchet teeth as the straight-cut teeth remain aligned as installed. The lever is not moving on its splines. The engine is a '62 Mototrans.

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I have measured the depth of the ratchet meshing which is full depth of the teeth - 2.5mm. The lift plate was found chewed at initial strip-down which was corrected with weld and the ramp filed to match that on the ratchet cog - ~45 degrees. All other components appear satisfactory although there is very slight play at the kick-start bush in the outer casing.

I had an Italian Elite in '67-'68 and don't remember that as a fault then so assume it can be eradicated.

Any thoughts on cause would be greatly appreciated.

[ranton_rambler]

Your ratchet teeth look a bit chewed up to me. I have that coil spring conversion on mine with no problems.
Ian

[Geordie]

Thanks for your response Ian.
The ratchet peaks are worn - (those on the mating cog very much less so) and there are chips on the straight-cut drive teeth. However, the straight-cut teeth aren't jumping and the ratchet is fully engaging. I am coming to the conclusion that I must acquire a replacement for both in better condition as the first step in a process of elimination. The engine is tight after rebuild which could be making matters worse for worn components, if that is the problem.

[DBDBrian]

As Ian comments Geordie, the ratchet teeth look to have taken a bit of punishment, which is quite likely the cause of your problem. I don't know if new replacement parts are available ? Good used would seem to be the best option, as it would require some deep thinking to effect a repair of the damaged parts. I realise this is not of much help to yourself, and I don't wish to hijack your post. This was my solution to a similar kickstart mechanism problem, it maybe of help to others in the future.
I had a quandary in as much as I had two ratchet pinions, one with worn ratchet teeth, and the other with good ratchet teeth, but very worn quadrant gear teeth. Fortunately the one with the good ratchet, had gear teeth cut round it's entire circumference, leaving unused teeth on the opposite side of the gear. The solution being to reverse it's operating position.
I also made a coil spring housing, replacing the weak leaf spring arrangement, Fingers crossed it's working OK to date.

Pictures not in order of assembly, as can be seen, also had to repair quadrant shaft bushing.

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[Geordie]

Brian, not a hi-jack at all: good solutions to worn kick-start mechanisms should be disseminated when parts become rare! Congratulations on a well executed work-around.

Thinking about the coil spring upgrade to the spring plate original arrangement, it was introduced by Ducati to overcome the ratchet jumping problem. That indicates that the ratchet requires a force greater than that supplied by the spring plate to hold it in mesh even when its teeth, in good condition, are fully engaged. As I have that upgrade, the wear on the teeth, as Ian has proposed, is now prime suspect. I note that you resolved your problem without changing the partner ratchet in the gearbox: as the teeth on mine appear to be as good as those on yours, I hope I am similarly lucky.

[DBDBrian]

Yes I used the best of the parts I had at my disposal, I am relatively new to tinkering with Ducati singles. The ratchet teeth are rather delicate for the force they have to deal with in the event of a kick back, and obviously any wear is not going to improve the situation, I gave the coil spring quite a bit of preload.
Something else learned after many years of starting Goldstar's , is to make sure the ratchet is fully engaged before a serious load is applied.
Another mod which I did not mention, was fitting a bearing with a shield on the side, behind the ratchet. As it is in a very vulnerable position in the event of any debris from further ratchet wear.

[ranton_rambler]

Here are my kickstarter ratchet parts for comparison. This all works fine with the coil spring modification that I fitted.
I'm not sure that yours are worn much more than mine so maybe you need to look at increasing the load on the spring?
Also, what are the teeth on the kickstart shaft like, and also the fit between the shaft and the bushes which keep it in position? When I got mine, the first 2 or 3 teeth were badly worn and the inboard bush in the crankcase was very worn. I sourced a good used shaft from Matt (Double Diamond on here) and had a new bush made.
Ian

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[Geordie]

Ian, thank you for that. Here are pics of ratchet and lift plate. The ratchet teeth on the gearbox pinion, without splitting the crankcases, appear satisfactory.

RATCHET.jpg

The lift plate was chewed so was built-up by welding. I filed the ramp at the same angle as that on the ratchet but note that that is much steeper than on yours. I will have to think on that as I'm unsure how it would contribute to the problem.

RAMP.jpg

When the ratchet is meshed there should, in theory, not be any force generated to cause it to move apart as the mating faces are parallel to the shafts, assuming no significant wear at bearings and bushes. The spring should be the motive power to cause the meshing and the kick-start return spring, together with the ramp, the motive power to decouple. However, as Ducati introduced the coil spring mod, there obviously is a force to be overcome.

The only significant (to my mind) wear I can find is with the meshing teeth of the kick-start shaft and ratchet. Bearings are new and the bushes are good although that in the outer casing shows some slight wear.

I have enquiries out with 2nd hand parts sources in Spain to see what might be available closer to original spec. I'll think more about the ramp slope and will increase the spring pre-load as suggested.

[LaceyDucati]

Looks to me from your picture, that you have two miss-matched components. The tooth form on the quadrant and the kickstart shaft look different. They should both have the same tooth form, unfortunately there is a myriad of different components across the years and models and Spanish and Italian parts vary. Also your ramp plate looks all wrong as it should just have a slope on one edge, but apart from that it should be flat. Most likely the quadrant is sticking due to the odd and damaged teeth. Also check the bushing is in good condition, as it can if worn allow the quadrant to kick out of line.

Hope this helps, unfortunately there are no replacement new parts and good used ones are like "hens teeth".

Regards Nigel