67 N15CS Build

The way the swing arm pivot is mounted is unusual. I like to have full circle rear engine plates with ends of the pivot spindle secured. With a dirt bike, it might not matter so much if you do not know where your rear tyre contact patch is, but the forces involved are still large.

Schwany said:

I have it boxed up and on a shelf. You might consider turning on the direct message function, so I could discuss details with you.

For the peanut gallery: I talked Chris out of buying the NEB clutch I have. It is a slightly difficult install in a P11 primary without trial and error modification. I would imagine it could be a similar PITA on a N15. The AMC clutch these old bikes came with is a bolt-on simple fit.

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I use an early AMC clutch behind my 850 motor. I did not believe it would withstand clutch starts in road races - it is another thing which I under-estimated about Nortons. It copped 6000 RPM on a start line, and did not give up.

acotrel said:

I use an early AMC clutch behind my 850 motor. I did not believe it would withstand clutch starts in road races - it is another thing which I under-estimated about Nortons. It copped 6000 RPM on a start line, and did not give up.

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My old AMC clutch was slipping on acceleration when I decided to replace it. I almost put it back in because I bought a new set of plates for it, but went with a diaphragm spring dry belt clutch, which for me is a better clutch with a lighter pull at the lever, and a lot less messy. It can take all the acceleration my engine can make and hold. I don't do 6000 RPM starts from a stop though. The exhaust note at 6000 RPM would draw a lot of unwanted attention on the street. Plus I don't like doing wheelies from a stop. Doing that makes me feel out of control and I wasn't born with the show off gene.

Thankfully, Schwany talked me out of buying his clutch. My goal is for reduced weight/stress where I can get it. I’m geared so low at 18/60 that I don’t think I’d miss the flywheel effect so much. It’s all moot, standard parts are in the mail to make my stock clutch right.

On a completely unrelated note - why doesn’t it seem like anyone is using triumph valve cotters in place of the Norton parts? They measure up the same and I can buy 3-4 triumph pieces for each Norton item. Alternately kibblewhite makes a tidy kit of HT cotters for a good price. What am I missing here?

Chris

Chris Johnson said:

Thankfully, Schwany talked me out of buying his clutch. My goal is for reduced weight/stress where I can get it. I’m geared so low at 18/60 that I don’t think I’d miss the flywheel effect so much. It’s all moot, standard parts are in the mail to make my stock clutch right.

On a completely unrelated note - why doesn’t it seem like anyone is using triumph valve cotters in place of the Norton parts? They measure up the same and I can buy 3-4 triumph pieces for each Norton item. Alternately kibblewhite makes a tidy kit of HT cotters for a good price. What am I missing here?

Chris

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I am not knowing, but I'll blab out something somebody that knows can disagree with and you'll get the right answer.

Best guess is Norton parts are over priced, or the Triumph collets don't actually work in Norton valve spring retainers.

Chris Johnson said:

Thankfully, Schwany talked me out of buying his clutch. My goal is for reduced weight/stress where I can get it. I’m geared so low at 18/60 that I don’t think I’d miss the flywheel effect so much. It’s all moot, standard parts are in the mail to make my stock clutch right.

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The NEB clutch has shortcomings. A sprocket made of 7000 series dural will wear fairly quickly. NEB should have made a bolted steel sprocket for the clutch hub. I believe the fitting problems Schwany experienced can be solved.
With a steel sprocket, the GPV clutch would be an attractive option. An inventive person may be able to alter the clutch hub?




AMC's clutch design has much going for it. Unfortunately, the clutch is prone to oil contamination because of its open design. When subjected to the torque of a Norton engine, owners will often experience clutch slippage. This was noted even during testing of new bikes.
Cleansing of friction plates helps - for a while. Fitting an external shielding of a thin-walled alloy sleeve would probably help a lot.

Another possibility is adaption of a Triumph T140 clutch w/7 plate conversion paired with a Commando engine sprocket, running a triplex or duplex chain.

- Knut

Knut, I have a GPV on the bench that I bought used on the hopes the splined hub would work, but apparently the speedway bikes use bigger jackshafts.

I’d also prefer a steel bolted up sprocket as I see some companies offering as a repair service. But just spitballing dimensions based on Schwany’s experience, the chainwheel ends up about 3/16” inboard when the clutch hub is positioned correctly, and there’s not enough thickness to the clutch drum to step it, bolt up a sprocket and correct the chain alignment.

Alternately, the clutch hub needs a 3/16” snout added on the backside and the splines shifted to match (basically what Schwany ended up with to make his work). More work than I’m interested in doing.

Chris

Chris Johnson said:

Knut, I have a GPV on the bench that I bought used on the hopes the splined hub would work, but apparently the speedway bikes use bigger jackshafts.

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Chris,

NEB Engineering provides a splined hub for the AMC / Norton mainshaft which fits Elite and GPV clutches.

- Knut

mdt-son said:

Chris,

NEB Engineering provides a splined hub for the AMC / Norton mainshaft which fits Elite and GPV clutches.

- Knut

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Yea I’ve seen it. From what I can tell you get the same relationship from the hub to sprocket and the same alignment problem.

Oh yea… and the pressure plate isn’t adjustable for the pushrod.

Chris

I figured out the valve collet thing - Norton valves are 9/32” in diameter at the collet, the others are 17/64”.

Chris

mdt-son said:

The NEB clutch has shortcomings. A sprocket made of 7000 series dural will wear fairly quickly. NEB should have made a bolted steel sprocket for the clutch hub. I believe the fitting problems Schwany experienced can be solved.
With a steel sprocket, the GPV clutch would be an attractive option. An inventive person may be able to alter the clutch hub?

View attachment 123103


AMC's clutch design has much going for it. Unfortunately, the clutch is prone to oil contamination because of its open design. When subjected to the torque of a Norton engine, owners will often experience clutch slippage. This was noted even during testing of new bikes.
Cleansing of friction plates helps - for a while. Fitting an external shielding of a thin-walled alloy sleeve would probably help a lot.

Another possibility is adaption of a Triumph T140 clutch w/7 plate conversion paired with a Commando engine sprocket, running a triplex or duplex chain.

- Knut

Click to expand...

Give all your fixes for installing a NEB clutch in a P11 a try, and get back to me. lol

I did make it fit with a Commando mainshaft and put a few miles on it. Never did get perfect chain alignment, but fairly close. The Commando mainshaft wasn't that happy inside the P11 gearbox and shifting was problematic. I put the original mainshaft back in the gearbox so I could use the AMC clutch. Bought new plates for the AMC clutch, but was by then very tired of dealing with the oily mess and went to a RGM belt clutch. There are many issues that made it a poor choice for a P11 primary. I seriously doubt NEB ever installed the clutch in a P11.

Schwany said:

The Commando mainshaft wasn't that happy inside the P11 gearbox and shifting was problematic.

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Commando mainshafts are exactly like pre-Commando mainshafts in the central section, just extended at the clutch end. If your shaft was straight and in good condition, the shaft as such wouldn't cause a shifting problems. Problematic shifting can only be attributed to clutch drag or failed alignment, in my opinion.

Achieving chain alignment shouldn't be a problem. There are shims available for that.

Fitting non-standard parts is often a tedious process of trial and error.

- Knut

Schwany said:

Give all your fixes for installing a NEB clutch in a P11 a try, and get back to me. lol

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I am inclined to fit a duplex chain drive to my G15 and P11 and I need a solution which incorporates a shook absorber. Hence, my primary interest is adoption of a Triumph T120 clutch.

- Knut

Chris: I would like to know who you bought the exhaust pipe kit from. The ones that I have looked at, all have a tight radius for the bends. I like the curves of your kit. Thanks

mdt-son said:

Commando mainshafts are exactly like pre-Commando mainshafts in the central section, just extended at the clutch end. If your shaft was straight and in good condition, the shaft as such wouldn't cause a shifting problems. Problematic shifting can only be attributed to clutch drag or failed alignment, in my opinion.

Achieving chain alignment shouldn't be a problem. There are shims available for that.

Fitting non-standard parts is often a tedious process of trial and error.

- Knut

Click to expand...

Knut,

When you install an NEB clutch in a P11 or N15 and get the sprocket and chain alignment set just right let me know how it goes.

Where do you think the shims are going to go in an NEB clutch like the one I have Knut? The clutch comes with one spacer shim. You can't move the clutch further away from the inner primary case with additional shims without more threads on the mainshaft or a different hub. You can move it closer though, which is nearly impossible since it scrapes on the inner primary fully spaced out with the spacer it comes with. What one can do (and what I should have done) is move the inner primary case further away from the back side of the hub and clutch. I did not do that until I went through the process of installing a belt clutch inside the little P11 primary. The belt clutch was not a standard Lego install by any means.

I know the mainshafts are the same theoretically. Unfortunately, the Commando mainshaft didn't spin freely enough for my liking, and I didn't want to tear the AMC gearbox apart and do anything about it. I also know the shifting problem could have been for other reasons, but I was having shifting problems right after installing the Commando mainshaft, not before. I don't actually know if the brand new from AN Commando mainshaft is 100% straight either.

I was done with the wet clutches and AMC gearbox and decided to move on. Now I have an excellent shifting Norton. The TTi gearbox did take some getting use to, but it is very nice. There are not many P11's with TTi gearboxes in them. Did the TTi gearbox installation ignoring all the unsolicited advice I got here. I would also steer people away from installing a TTi gearbox in a P11 frame unless they make a new longer primary cover, so they can use a longer belt and get the gearbox back further from the timing side case so the oil lines can be run above the gearbox and down into the junction block rather than under the gearbox and up to the junction block.

Knut feel free to lay the doom and gloom on me related to the running the oil lines under the gearbox. I already know what the issues are, but I'd like to hear what you come up with.

I'm not yet another Lego motorcycle builder telling people how to do anything. It's very difficult to give useful advice in a message box.

Sorry about the BS Chris, but you started it. Kidding except for being sorry about all the typing.

franko said:

Chris: I would like to know who you bought the exhaust pipe kit from. The ones that I have looked at, all have a tight radius for the bends. I like the curves of your kit. Thanks

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Franko, I think we spoke several years ago when I was trying to sell this bike. I couldn’t get what I needed out of it so here I am, completely upside down in it…

I buy mandrel bends from SPD Exhaust. I used one 2” radius bend at the timing side port and the rest are 3” radius. I’ve used their 4” radius bends on a rigid triumph to get the best fit around the primary chain case.

All that said, I’ve now found JMD Tubes with about the same inventory, better prices and online shopping but I’ve only bought a single piece of straight tubing from them.

Chris

Thank you for the information.
As soon as I saw the two rims, I remembered it.
I ended up buying a G15 in Santa Rosa, Ca. I didn't want a perfect bike for what I was going to do. It wasn't perfect, but ran and rode.
This is the project: https://www.advrider.com/f/threads/66-matchless-g15-and-soa-eagle-sidecar.1435574/
Where the thread ended, is when I went through divorce. It doesn't just mess with the money, but the mind also.
I am ready to start again on it. More parts were bought. New information on what to do. When it is usable, I will ride it and make changes. The fender on the side car funnels rain water into the tub. I will fiberglass an edge to divert it. I would like to design/make a top for it. Something with fiberglass rods and tubing. Similar to how some tents are made. When all the mods are done, I will use it so it can prove itself. When everything is good, the following winter will be tear down and make pretty time.

I feel like I’m getting down to the wire. I’d like to have this running by the end of the month. Tonight I got the crankcase buttoned up which should get things moving at a quicker pace for a bit.

Mismatched crankcase halves, Richter Machine-prepped crank, NOS rods & JS1 cam.

Chris

A little progress this weekend, seasoned with a healthy dose of frustration. I broke a compression ring Friday night while rushing, luckily CBS is nearby and they saved me with new rings on Saturday. Again, while rushing, one of the oil ring expanders got loose on me, separated and launched the little connecting wire into the abyss of my garage, setting off a fruitless all day search/garage clean out. Today I mixed the old tech 3-piece oil rings with the new tech coated compression rings and was able to claim success.

Also swapped the gearbox cam plate to fix the awful GP shift pattern, checked initial cam timing (needs a few more degrees) and finalized the exhaust mounting.

Does anyone have the long footrest engine plate spacer tube handy? I need a measurement of that spacer - I made mine at 3-11/16” which matches the width of everything above it but it seems to pinch down to 3-5/8” at the lowest 5/16” crankcase stud. It doesn’t make sense to me and I’d like to know what the original spacer measures before I make any changes.

Chris

Looking through the magneto mount, I can see the head. I think it was @ludwig that came up with the idea of drilling a hole through the fins at the valley, between the two bolt holes. This allows air to move through what would be a dead air space. This helps with cooling what would be (to me) the hottest part of the head.