Norton N15CS Hybrid restoration

I could have sworn I had those bits in my little cardboard "finish bits" box...

Having said in my previous post that I never saw one of these in the flesh, I saw one today! Or at least this does look similar to your customer's machine. However, the exhaust pipes are low slung, and to my inexpert eyes look like those from a Dominator or early Fastback. Were the high level pipes offered as an optional extra or are the pipes shown here not the right ones? Or is this a different model?

daveh said:

Having said in my previous post that I never saw one of these in the flesh, I saw one today! Or at least this does look similar to your customer's machine. However, the exhaust pipes are low slung, and to my inexpert eyes look like those from a Dominator or early Fastback. Were the high level pipes offered as an optional extra or are the pipes shown here not the right ones? Or is this a different model?

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That's the one. and a very NICE one at that! As near perfect as i've seen!

This client specifically wanted the shouldered alloy wheels and P-11 upswept pipes apart from original spec otherwise.

What a nice looking bike. This is the usual exhaust configuration, the primary cover is a shortened Commando cover like Ludwig has done on his lovely G15/Commando, Photos of which can be found in this section under 'Commando engine into a P11 hybrid rolling chassis' (page 6). I am intending to do something similar as soon as I have finished some of my other pending projects.

dave M said:

What a nice looking bike. This is the usual exhaust configuration, the primary cover is a shortened Commando cover like Ludwig has done on his lovely G15/Commando, Photos of which can be found in this section under 'Commando engine into a P11 hybrid rolling chassis' (page 6). I am intending to do something similar as soon as I have finished some of my other pending projects.

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OK, found the thread and link to the article. Very interesting.

grandpaul said:

Foxy, I took a set of P11 pipes, cut and re-fit them to clear the N15 sidecovers, then welded them up. I then took the pipes down to my painter to have him carefully crind and sand down the welds so that AFTER they get back from chrome (in about 2 weeks) they'll look seamless again.

...don't panic!

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I also think so.thanks




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I posted a photo of an N15CS on this thread in September. I caught up with the owner last week when he was out for a ride. I had a closer look at the timing side of his machine and noticed this anti-sump device. Thought it might be of wider interest to those of you who might be considering fitting such a device to your Norton. Not discreet, perhaps, but then maybe it needs to be obvious! The tap handle has a neat little lever on it which activates the switch connected to the ignition. You can't switch on the ignition without turning on the tap fully.

You can also just see a neat electronic mag conversion, partially obscured by the kickstart rubber.

Grandpaul — any update on your rebuild?

Hi there , about that "electric" oil tap , i had got one from UK for a commando , they are made by an old mate of the matchless owners club , if you want , I can give his email , Pierre.

This project got side-tracked from April till June, then again from late September until 2 weeks ago. I hurt my back pretty badly, trying to kickstart it; it's got a ton of compression, but also some turning resistance somewhere in the clutch and/or tranny. Right noww I'm sorting the tranny and clutch out; it's a nighmare to get the primary cover off the engine, you almost have to disassemble the whole bike except the front brake lever.

marinatlas said:

Hi there , about that "electric" oil tap , i had got one from UK for a commando , they are made by an old mate of the matchless owners club , if you want , I can give his email , Pierre.

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Pierre, I didn't know that. I thought it was a "one-off". I think it's simple and effective, like all good designs. Thanks for your offer. I don't need one myself, but forum members will now know where to get a switch if they contact you.

grandpaul said:

This project got side-tracked from April till June, then again from late September until 2 weeks ago. I hurt my back pretty badly, trying to kickstart it; it's got a ton of compression, but also some turning resistance somewhere in the clutch and/or tranny. Right noww I'm sorting the tranny and clutch out; it's a nighmare to get the primary cover off the engine, you almost have to disassemble the whole bike except the front brake lever.

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Grandpaul — sorry to hear the cussed thing hurt your back. It hate it when you encounter something that's stiff to rotate when everything is buttoned up. We hope you have a swift recovery and we look forward to your next post!

Figured out the problem and removed the incorrect shim from behind the clutch basket.

Now on the downhill side to finish this thing up before the Spring thaw in NC...

Struggled with the clutch today; spring spacers to get a "full" lever travel & good grab with fully free clutch when pulled in. Took some doing, as the adjusters were mismatched, so I've sorted though several bins to get the three best ones to get a good range of adjustment out of them. Also rounded up every clutch spring in the entire shop to pick out the three longest / closest match springs for good lock-up.

Re-shimmed the inner primary (it kept rubbing on the primary chain backside); ended up using a thinner backing washer on the stand-off to give it more clearance and still let theprimary case seal up properly. The wimpy OEM paper gasket is going to need to be a thicker modern type to seal everything up right, so I need to order that. Besides, the fit on the paper gasket was too tight and had started to tear near the alternator area.

Got the drive chain sorted (had to loosen off the tranny to get the right spacing on the links so it wouldn't be too tight). Previously, the incorrect shimming on the backside of the clutch basket made the sprocket too tight to turn easily, so that's cured.

It's got a much easier kick now, with full compression. I'm rebuilding a set of 930s and the Mikuni that was on it, to settle which solution is going to be best on the carburetion.

This beastie is gonna be making noise soon! (the good kind, from the pipes)

Thanks so much for keeping us posted on this wonderful project. I can see that a lot of folks are following along with your struggles and progress. I see a lot of similarities with my own long delayed Matchless G80CS project. The frame & many of the cycle parts look the same.

You are having a lot of trouble getting the engine, transmission & primary drive sorted out. Is this because of the new engine/transmission plates or is this just the norm?

Paul
SoCal

Two issues:

I had my assistant disassembling some parts of the engine and chassis, and he diudn't take any photos of those bits.

The parts books for this range of models HAS NO ILLUSTRATIONS!!!

The engine plates are not an issue.

Okay, time for an update.

Between all the stuff that's been going on out here in the desert southwest, I've been flummoxed by this balky engine. Try as I might to sort the clutch and tranny, it seems like I can't get more than a thump and a half out of the lump with my best kickstarting efforts.

So, I decided to "go in" one more time. Here's what I've found:

- Crankshaft will just start to rotate past high compression at about 10-12 ft/lbs of torque



- I checked to make sure the clutch basket wasn't rubbing on the backside and it's definitely NOT. Splined shaft length is .85", basket female splined socket is .73"; so, there's no way it's bottoming out on the backside before the shaft bottoms out in it's socket.





Just for grins, after removing the primary assembly, I did a test pull on the kickstarter to measure resistance in the tranny's kickstart circuit - 7-1/2 lbs. produces shaft rotation. Nearly all of that is in the return spring.



Before I yank thge engine out of the chassis, I'm going to investigate the camchain & oil pump, but with only 10 ft/lbs on the crank nut to turn it, I doubt the power unit is where the resistance is happening.

If anyone reading this has an N15, G15, P11 or other late 60s 750cc Norton engine with the primary off, I'd sure appreciate you measuring the stuff I measured and see where I stack up here...

Paul, what's it like to kick over with the plugs out? Could it be that a previous owner skimmed the head and you have higher than normal compression? I would try to start it with some rollers on the rear wheel and run it for a bit to see if it just needed settling down.

WIth the plugs out, it's totally normal.

Ring end gap is by the book.

I suppose I could try the rollers, but the client needs to be able to kickstart it normally, so it should be settled properly. Rollers are a last resort.

grandpaul said:

Rollers are a last resort.

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If you are injuring yourself just trying to kick it over, then that 'last resort' is already sailing over the horizon ??

BTW, Atlas engines came originally with pistons with a fair old dish (down) in the tops of the pistons. Why was that (less vibes ?), and are these pistons still available ?

Once it's actually going you can get the timing, carbs, valve clearances etc dialed in and after a quick run up the road you may find that some of your problems have dissappeared.

Rohan said:

BTW, Atlas engines came originally with pistons with a fair old dish (down) in the tops of the pistons. Why was that (less vibes ?), and are these pistons still available ?

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Enlarging the original 500 Dominator engine to 650 was already considered by certain people at Bracebridge Street to be overstretching the original design somewhat, and that going to 750 was simply pushing it too far! The 750 Atlas was originally intended to be a softly-tuned touring model, the low compression resulting in a maximum power output about the same as the 650SS and thus kept the Atlas vibration (and engine failures) down to what was considered to be an acceptable level.

However, when Norton moved to Plumstead, Doug Hele left....and things changed.

The following paragraph regarding the introduction of the Atlas is an extract from Steve Wilson's book 'Norton Motor Cycles (From 1950 to 1986)'.

"Other changes for the 750 included concave pistons and a different shaped combustion chamber, giving lower compression. It should be noted that Doug Hele had been emphatic that the compression ratio on this stretched design should on no account be raised above the 7.5:1 cr he originally specified. The raise to 9:1 shortly after the move to Plumstead, and the subsequent Combat Commando follies, were all in direct contravention of this distinguished developer's recommendation.

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