N/G 15 primary cover

@ludwig: Is this how you were able to modify a Commando cover to work on your N15.


Thank you

Sorry for the late reply, but they seem to be the std Commando cases.
You can use them, but they are too bulky imo.
I cut and rewelded the cases ( red outer, blue inner) , no more drain plug.
Also reduced the outer rim, the groove for the rubber seal is gone.
In all, a much narrower and smaller case.
I also cut out the section behind the clutch, to gain access to the chain sprocket.

Thank You Ludwig: It gives me something to think about.

Franko,

Like Ludwig said, the Commando primary is too large (long) for the G15 (crankshaft to mainshaft distance). Location of engine and gearbox differed between Commando and G15. NV provided offsets everywhere to create a working drive line. This isn't easily adaptable at the G15.

Before attempting to copy Ludwig's work, you should read up on welding aluminum of thin WT. It's a tricky job.

I think modification of the standard primary cover is easier to accomplish. Do you prefer the shape of domes at the Commando cover over the AMC domes?
There is always the possibility of casting your own outer cover. 22 mm belt drives will work when using AMC covers and a spacer between them.

Things would have been so much easier if the countershaft sprocket had been located at the timing side, like it is on the 961.

- Knut

Of course it would be easier to space out the original cover to create room for a belt, but the Commando inner has a few advantages, like centering the alternator, strobe timing, etc..
I never liked the stator in the outer cover.

Agreed, and all of these features could be incorporated in a new outer cover. I have seen a picture of AMC's outer cover modified to include an inspection cap for strobe timing.
The stator mount could be realized by adapting the stator mounting off the Norton Atlas, or similar posts welded to the AMC inner cover. Such a mod requires careful planning and execution, of course.

- Knut

Regarding using the AMC primary and installing a belt clutch:

I'm not the first to install a belt clutch inside the AMC primary by a long shot, but I have done it.

Kind of amazing that the stator is never out of alignment with the rotor on my P11 and I have had that cover off and back on at least 50 times.

With a 3/8" full perimeter spacer you can get a 25mm belt inside a P11, G15, N15 AMC primary. However a lot more needs to be done inside both the inner and outer cases to get clearance for both the belt and the basket. Also the foot pegs may require some imagineering. A 21mm belt is enough for most 750 engines used on the street. I do run a 25mm belt.

Once a belt is fit inside those cases it would be very difficult to go back to a wet clutch and expect the primary to hold oil and never drip. I'm sure it could be done, but a diaphragm sprung belt clutch is far better than a 3 spring AMC clutch. Getting a belt clutch in there is worth the commitment, but it will lower the value of your N/G 15.

I drilled a 5/8" diameter hole in the outer primary for strobing the timing. I mark the rotor and stator. I seldom use it though.

One other hack I did was run a 1/4-20 tap through the perimeter bolt holes and use longer 1/4-20 allen head bolts to hold the outer primary cover on with a 3/8" spacer in place. Surprising that the bolts actually hold and stay tight. The alignment dowels also have to be pulled out a little or replaced with longer dowels. Dowels may not be the right term, but if one isn't too anal it should be obvious what I am talking about.

Side note: The gearbox on a P11 can be moved quite a way back, so if the N/G have a similar gearbox adjustment getting a modified Commando primary on might not be that difficult. I thought about it, but wanted to keep the AMC case look.

Schwany said:

Side note: The gearbox on a P11 can be moved quite a way back, so if the N/G have a similar gearbox adjustment getting a modified Commando primary on might not be that difficult. I thought about it, but wanted to keep the AMC case look.

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I remember vaguely there is an interference problem between Commando inner primary cover and the G/N15 swinging arm. Space is rather tight already when stock parts are fitted.

- Knut

mdt-son said:

I remember vaguely there is an interference problem between Commando inner primary cover and the G/N15 swinging arm. Space is rather tight already when stock parts are fitted.

- Knut

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I can believe that. The Commando primary is probably 1/2" too long for a P11 frame as well. I definitely thought about trying to use one, but I lacked the initiative to follow through. I've seen them cut in half with an open S-curve cut. Some ingenuity would be required to mount the rear section, but it should/would/could be easier than cutting the cases and welding them back together.