67 N15CS Build

Chris Johnson said:
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
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I don't have my bike in my garage, so I can't look (son borrowed it), but I found this for PN 030237

https://www.walridge.com/product/sp...otrest-rod-and-centrestand-spacer-g15-models/

Seems to fit the bill, measurement and location-wise, but it's not called out for the N15CS, prob just a miss in the book, since it calls out the G15CS.

67 N15CS Build
 
Perfect, thank you. I never think to check walridge.

I think someone must have narrowed the welded on spacer at the lower crankcase stud, it measures 1/16” less than the others. I’ll shim it and move on.

Some white metal flake and other fun paint supplies arrived today…

Chris
 
gpzkat said:
I don't have my bike in my garage, so I can't look (son borrowed it), but I found this for PN 030237

Seems to fit the bill, measurement and location-wise, but it's not called out for the N15CS, prob just a miss in the book, since it calls out the G15CS.
Click to expand...
Tom,
I have never had the chance to examine footrest fixing of a G15CS.

However, I believe 030237 fits the normal (roadster) footrests and the square rod ONLY. The reference to "1968 G15CS" is a printing error - it should read "1968 G15CSR", a one year only model which also had the roadster type of footrests, see #018601 above.

i am not convinced this spacer was ever fitted to the CS model - which didn't really need one due to the footrest design. There are two lugs at each footrest casting which clamps to the frame rail, so the footrests are fixed, the locating bolt doesn't need much tension, and a spacer between the rails becomes superfluous. Roadster footrests do not clamp the frame rails and requires tensile force at the rod. Here, fitting the spacer makes sense.

For the record, spacer 030237 is 11/16X7/8X3-11/16 according to Domiracer.

Footrest rod 018604 (the square one) probably works, but .... I wonder if the circular rod 016462 "Rod, footrest" off the G80CS is a better match? Footrests themselves were derived off the G80CS, and the frame rail spacing should be identical.
Footrest castings have a circular aperture for the footrest rod, suggesting that a circular rod was intended indeed.

- Knut
 
mdt-son said:
Tom,
I have never had the chance to examine footrest fixing of a G15CS.

However, I believe 030237 fits the normal (roadster) footrests and the square rod ONLY. The reference to "1968 G15CS" is a printing error - it should read "1968 G15CSR", a one year only model which also had the roadster type of footrests, see #018601 above.

i am not convinced this spacer was ever fitted to the CS model - which didn't really need one due to the footrest design. There are two lugs at each footrest casting which clamps to the frame rail, so the footrests are fixed, the locating bolt doesn't need much tension, and a spacer between the rails becomes superfluous. Roadster footrests do not clamp the frame rails and requires tensile force at the rod. Here, fitting the spacer makes sense.

For the record, spacer 030237 is 11/16X7/8X3-11/16 according to Domiracer.

Footrest rod 018604 (the square one) probably works, but .... I wonder if the circular rod 016462 "Rod, footrest" off the G80CS is a better match? Footrests themselves were derived off the G80CS, and the frame rail spacing should be identical.
Footrest castings have a circular aperture for the footrest rod, suggesting that a circular rod was intended indeed.

- Knut
Click to expand...
I was going to say that I wouldn't be surprised if there's no spacer on my bike, as I followed the parts list. Mine has the square rod 018604. The whole setup seems a bit of a contraption, but works. The spacer's dimensions are in the Walridge link, but I see it got trimmed.
 
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There definitely should be a spacer. It is part of the rigid engine-frame setup.
I modified my footrest mount, so I can't give you the exact dimensions.
 
ludwig said:
There definitely should be a spacer. It is part of the rigid engine-frame setup.
Click to expand...
You are right. The spacer is needed, not so much for the footrests, rather for engine/gearbox fixation.

So, there are 3 spacers involved:
030237 with dimensions 11/16 x 7/8 x 3-11/16"
030235 " " 11/16 x 7/8 x 0.343" (2 off)

Rear engine plates feature a square hole for the square rod 018604. However, the frame lug has a circular bore, so rod 016462 could be fitted by altering the engine plates.
This should stiffen up the chassis somewhat.

- Knut
 
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There is a left and a right hand footrest hanger. I've never reflected on the difference between them. Anyone?

- Knut
 
Chris Johnson said:
Mismatched crankcase halves, Richter Machine-prepped crank, NOS rods & JS1 cam.

Chris
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What did you do to make the mismatched crankcase halves join properly? I have a few sets of nonmatching crankcases. They require machining before I can join them to an oiltight assembly. By then the bearing C/C distance and the camshaft won't fit. A spacer between the machined halves would have to be furnished, or do like the factory did - mate one half to an unfinished crankcase half.

- Knut
 
Knut,

Maybe I got lucky: the register & pins lined up and the crank & cam bearings also lined up, only requiring that I match the cylinder mounting face.

Generally speaking, in this hobby (not Norton specific) I’ve read many suggestions that the cases are assembled then line bored. Lacking any first hand knowledge, I think the case halves were machined individually so the bearing bores are kept perpendicular to the mating faces, the crank bearings are concentric to the register and the cam bearing is held to an accurate location, all in a single setup, then bolted up to machine the cylinder mounting face. Having a semi skilled machine operator trying to set up a line bore for crank bearings that you cant measure from outside the case on an assembly line seems counter intuitive.

But like I said, maybe I just got lucky. I did hunt for a donor crankcase that was t very far off in serial number in hopes that the original setup hadn’t changed much.

Chris
 
Maybe I got lucky too. My (thankfully) non-numbered half was damaged, and I got a replacement on eBay. No problems. In my case, ignorance was bliss, though I do remember Knut mentioning it back when I was posting my updates. My bike has that spacer, just took a look.

67 N15CS Build
 
Chris Johnson said:
Maybe I got lucky: the register & pins lined up and the crank & cam bearings also lined up, only requiring that I match the cylinder mounting face.

Generally speaking, in this hobby (not Norton specific) I’ve read many suggestions that the cases are assembled then line bored. Lacking any first hand knowledge, I think the case halves were machined individually so the bearing bores are kept perpendicular to the mating faces, the crank bearings are concentric to the register and the cam bearing is held to an accurate location, all in a single setup, then bolted up to machine the cylinder mounting face. Having a semi skilled machine operator trying to set up a line bore for crank bearings that you cant measure from outside the case on an assembly line seems counter intuitive.
Click to expand...
Chris,
Searching for a crankcase close to the other half's serial number was a smart move. AMC machined crankcases the way you described (I have pictures to support it) , the "register" being the joining face acting as a datum surface. There is another thread on this site discussing design references and heights.

Line boring and machining of bearing seats when both case halves are joined would require guidance by external bosses. I can't see any boss machined accurately enough for insertion into a boring jig.

Even if you are lucky to find a crankcase close to the other half's serial number, there is one effect you can't prepare for - distortion. Whether a result of an exploding crankshaft, a violent crash, or release of residual stresses due to high heat, alloy easily deforms. Once the case half shows warpage, the datum surface is gone. These case halves possess low out-of-plane stiffness, so yes, you have to be lucky finding a case half which hasn't distorted.

- Knut
 
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Gotta celebrate the little victories:

I had to replace the cush drive rubbers and couldn’t quickly find a cheap mainshaft to hold the spider. So today I made up a rough splined stub that’s easily grabbed in a bench vise. Last time I did this job on a Triumph without the right tools was a nightmare.

Chris
 

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ludwig said:
The angle how they fold up .
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Here is a NOS sample of 030474 Left hand footrest hanger. AMC didn't bother saving weight on the hangers! There was a detail change to the left hanger, allowing the primary cover to be taken off with footrest hanger in situ. I'd like to see the previous version, if anyone has got one. It carried the same part number.

- Knut

67 N15CS Build
 
gpzkat said:
Cush drive? How cushy is that? I didn't know they had them. Oh, I'm thinking rear hub.
Click to expand...
A proper rear hub with cush damper is available with Donald Pender. You may have seen it. It's a very nice piece overall, preserving the Norton hub appearance.

- Knut
 
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Chipping away at a bunch of little tasks…
Engine finished
Magneto is stripped, waiting on a few parts
Carbs finalized, need to find a new 3-1/2 slide for a 689
Exhaust at ceramic coating
Various pieces at powdercoat

I expected the small details to drag me down and they are.

I’ve been playing with the paint, will pinstripe & add logos after this round of clear coat cures.

Chris
 

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I started going down the road of original carbs and got some deals on monobloc carb bodies and slides, but the single Mikuni is easy-peasy, and I don't need additional headaches. PM me if you want to see some pics and info. I might have something you need.

I had a nice original air filter housing, good chrome, but I sold it to fund other stuff. C'est la vie, my Laverda is now taking my time and the Norton just needs riding and normal upkeep.
 
My carb choice was determined by finding a NOS 1-3/16” 689. Then I held out as long as I could to find a NOS 389, to no avail, and had to buy a new one. The only negative is the two carbs don’t match.

My original monoblocs were pretty well damaged and I didn’t want to do all this work and compromise on carbs.

Also, taper boring the inlets for the larger carbs found a respectable increase in inlet flow without hogging out the narrow part around the valve guide.

Being new/not filled with soot, now was the time to finish the exhaust. For the style I had in mind, either chrome or black would be appropriate. I chromed a Triumph exhaust and it took something like 6 months so I went with ceramic for this (I had them do my B50 exhaust previously). Also I didn’t metal finish the pipes for chrome - all the welds are present and visible. Ceramic isn’t much of a savings over chrome, for comparison. Oh, I want a finish that would last longer than paint.

Chris
 

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