5 speed Narrow case Kickstart gear

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Jeb
Posts: 20
Joined: Wed Mar 18, 2015 1:30 pm
Location: Battle UK

Re: 5 speed Narrow case Kickstart gear

Postby Jeb » Wed May 02, 2018 4:58 pm

Bob, the kickstart gear runs on a bronze bush which on mine was quite badly worn allowing the gear to tilt sideways. This means that the gear teeth do not engage fully with the gear on the gearbox shaft.
I made a new bush for mine and although when I first started the bike a couple of weeks ago the gear seemed to not engage properly, I think this was due to me making the fit a little too tight as it has improved a lot having started it a few times now and only misses the first tooth very occasionally.
If your gear does turn out to have very worn teeth, there is a chap local to me who races narrow case Dukes and they usually remove the kickstart assy, so there is a possible chance he may have a spare.

double diamond
Posts: 555
Joined: Thu Apr 28, 2011 1:20 am

Re: 5 speed Narrow case Kickstart gear

Postby double diamond » Wed May 02, 2018 8:13 pm

Bob,

I had a look through some 5-speed NC kickstart components and made a few discoveries that you should be aware of. Referring back to my post on the 4-speed kickstart mechanisms, I observed that there were two different designs for the 4-speed engines. Also included was an example of the 5-speed design and a pic of the mechanism. Pictured was the “involute tooth” type. As it turns out there is another design that probably preceded the involute tooth design. This is a 5-speed mechanism with the flat tooth profile that was employed with the 4-speed designs. The two designs are otherwise very similar, if not identical, other than the gear tooth profile. If you need to replace your kickstart gear or shaft and the other component is serviceable, you’ll need to find the correct tooth profile that is compatible with the other component.

There is a ramp integral with the kickstart gear that retracts the gear from engagement with the ratchet mechanism. This ramp bears on a steel plate fastened to the cases. This plate can wear as well as the ramp on the gear. Both could be welded to bring back to spec.

The other wear point in the design, and probably the most vulnerable, is the ratchet teeth on the kickstart gear and first gear. As you can see in the accompanying pic, the ratchet teeth on the involute-type gear are chipped. These teeth can also become rounded. Either condition can affect engagement of the kickstart mechanism. These ratchet teeth seem to be the source of most kickstarting problems in a properly running engine. Severe kickback in a poorly tuned engine leads to damaged/broken teeth in the kickstart gear/shaft, chipped/rounded ratchet teeth and damage to the engine cases. If your Ducati doesn’t suffer from severe kickback, the source of your starting problems is more likely to be the ratchet teeth. As observed by Jeb, a worn kickstart gear bushing would lead to poor engagement of the ratchet teeth (engagement of the ratchet is only a couple of millimeters) and eventually lead to rounding the teeth. The other wear point is the bushing in 1st gear that supports the left end of the transmission shaft, but that is another subject.

Hope this gives you some insight on what to look for when you inspect your kickstarter.

Matt
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Bevel bob
Posts: 1042
Joined: Thu Apr 15, 2010 8:01 am
Location: Bromley Kent UK.

Re: 5 speed Narrow case Kickstart gear

Postby Bevel bob » Thu May 03, 2018 5:00 pm

Thanks Guys this is really good stuff, so usefull to those that follow . This is a fantastic resource ,long may it continue. Took my 250 round to a local engineer who is going to press my stand straight,make me a remote float bracket and bracket to pull the exhaust in tighter. On the way back I hit a pothole and the front brake cable cought up on the clip on clamp and locked the brake on hard. No tools so well stuck ,could not even put the bike on the stand as wheel locked solid. A passing old couple stopped and lent me tools ,then their car would not start!, Fixed all and went on our ways. Just like in the old days.

ranton_rambler
Posts: 439
Joined: Sun Jun 04, 2017 11:33 am
Location: Stafford UK

Re: 5 speed Narrow case Kickstart gear

Postby ranton_rambler » Fri May 04, 2018 4:40 pm

Ducadini wrote:Didn't read the whole topic but I know there were two types of spring used to push the kickstartgear into the gearboxgear.
First type was a Y-type with a little bend in the upper parts.
Second was a ordinary coil with a special "bridge" over it .
Nothing interchangeable, but with a bit of drilling, tapping and screwing the second can be adapted.
Sorry, no pics readily available.

ciao
ducadini

I bought a kit to convert mine to coil spring, following instructions in the Tech section. As it's dismantled I clamped the case in the pillar drill at work to get it all nice and square. Also had to make a bush to support the kickstart shaft, and find a new shaft. The latter was supplied by Matt from this forum. Not in a position to try it yet, but getting there....


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