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I have started to redo the engine in my 1964 Mach 1S (vin 00007). Among other things, a chunk of alloy has broken out of the hole for the kickstarter shaft (picture attached). I've seen other postings that indicate this isn't that uncommon and they recommend making a bushing out of a stronger material (and perhaps weld repairing the damage). However this engine did not have a bushing in it; the hole in the case is just slightly larger than the 15 mm shaft. (also missing is the 0.5mm thrust washer and the "segment locking plate" that is shown in the parts book-there is a thin shim). I don't understand the purpose of the "segment locking plate" so any info on that would also be appreciated.
So has anyone ever seen a similar situation? I can see several possibilities: weld repair and rebore the hole, open up the hole and insert a custom bushing (either with or without weld repair first), ignore and pray (no doubt a bad idea).
In spite of all these missing parts the kickstarter worked ok.
Finally (for now) any thoughts on brand for main bearings (the left side one is toast-haven't checked the right side yet).
Thanks in advance for you advice.
Phil

Phil,
Your case likely broke from a kickback while kickstarting it. The N/C kickstarter design is pretty marginal so the kickstart shaft bore in the center case can use all the help it can get. I’d recommend welding the section that broke out, bore the case and install a bushing. The segment locking plate is basically a sacrificial part that protects the kickstarter stop in the case. If the engine kicks back when attempting to kickstart it, the stop on the kickstart mechanism hits the center case with enough force to cause damage. The segment locking plate takes the impact rather than the case. Many of these plates I’ve seen are mashed pretty thin from repeated kickback.

Ducatis of that era came with Italian RIV bearings or German FAG bearings. RIV is long gone, FAG brand can still be had but they’re made in in Korea now. Seem to be good quality though. Any brand name bearing (Koyo, NTN, OKI, SKF, FAG, etc.) will be fine for main bearings as long as they are same specification.

Now that you have the cases split, perhaps you could post a pic of the M1S connecting rod and anything else that looks unusual?

Matt

Here are a some pictures. There are no markings on the rod and it looks different than the rods I've seen for sale on e-Bay. Anyone out there know more about this?
Phil

that a S conrod indeed . i think the gear that drives the oilpump is moved over a little to compared to a regular crankshaft .

a have the lefthand side case of a Mach1S . the hole where the kickstartershaft goes into is 15mm with no bushing

there are a few other Mach 1S owners out there in the USA . i know who ownes nr 9 and number 10 .
nr 23 is in Japan and nr 25 is a set of new crankcases .



Eldert

M1S nr 23 had straight cut primary drive

Eldert