1973 850 Rebuild

1. Crankcase reed valve, most agree good things happen with this. Several options.
2. Anti Wet sump valve, lots of opinions, highly disputed.

I currently have the crankcase reed valves on both my 72 and 74.
The 72 has the rear mount, the 74 has the NYC Norton sump valve. JC developed this and may have them.
With the crankcase reeds, a few soft kicks pumps some oil out of the crankcase, once fired it clears itself.
I don't concern myself with wet sumping.

Time Warp said:

That is why I mentioned the bronze stud inserts yesterday since the head is at the JC shop, they out perform all other options (it seems) with the stock fine pitch stud.
Unless you must have snazzy reduced or wasted shank UNC studs.
My point yesterday, whizz bang is not the be all.

Like you said, do it once, do it right.

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Unless I miss watched the videos posted, the stud that ‘necked’ (ie the threads stripped on the stud and not in the insert) was a fine 20 TPI thread. I haven’t asked him specifically, but I assume that’s why Jim makes the UNC (16 TPI) versions.

On the other bolt topic, ie ‘whizz bang’ reduced shanks: these are used on perhaps every modern engine made.

Are all these things ‘necessary’? Absolutely not.

Are they ‘beneficial modifications that are worth considering during a rebuild’? Very much so!

Well, IMHO at least.

Just to bring this stud and bolt debacle back to Jerry’s original topic...

This is what I personally consider a sensible upgrade to consider whilst doing a rebuild. The small 12 point heads enable good sockets to be used, dispensing with the need for a collection of box spanners and fiddling. The reduced shanks allow stretch with is good for head gasket sealing without over torque damaging the threads or the alloy etc. They’re in top quality stainless. They’re made by ARP who are the best in the business. AND you get the 3 UNC studs thrown in too.

Sure, they’re not needed but that‘s a lot of known issues / niggles tackled, all for a little over $100 more than new standard parts would cost. IMHO that’s not a lot of money and nor is it whizz bang:

Fast Eddie said:

Unless I miss watched the videos posted, the stud that ‘necked’ (ie the threads stripped on the stud and not in the insert) was a fine 20 TPI thread. I haven’t asked him specifically, but I assume that’s why Jim makes the UNC (16 TPI) versions.

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Fast Eddie said:

Just to bring this stud and bolt debacle back to Jerry’s original topic...

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There is no debacle, all I suggested was OP consider getting the three threads Al/bronze inserted since the head is not only at JC's workshop but he is local to the OP.

A stock stud is 20 TPI in the head and 26 TPI at the fastener, 16 TPI UNC at the fastener would most likely result in the fastener coming loose.

What the video showed was the stock 20 TPI thread in the head failed at 49 ft/lbs (short stud) and 50 ft/lbs (long stud) or 19 and 20 ft/lbs above the recommended factory torque of 30 ft/lbs. (A surprise ?)
The head with the Al/bronze insert failed at a massive 66 ft/lbs or over double the recommended factory torque with an assumed 20 TPI thread in it to suit the stock stud.
Point, you will never pull that stock stud / insert configuration out of the head.

In the other video that has various 16 TPI UNC thread reclaim methods the winner was the Helicoil at 35 ft/lbs failure or a 5 ft/lb margin of failure above the recommended torque of 30 ft/lbs.

Note the three CNW black studs are short on the coarse thread end (16 TPI ?) and long on the finer thread end (fastener end ?)
If so and based on the thread pitch there is maybe a 1/2 inch of thread engagement in the head.

I did notice in the Helicoil etc video, at the end there looked to be a JC Al/bronze insert option with assumed 16 TPI so the aftermarket studs could be used with those.

CNW make some very nice products but would be wasted on my budget 850.
I will leave it at that.

I never suggested 16 TPI at the fastener end !

JC insets in the head with a 16 TPI thread would be the strongest thread. If buying new hardware anyway, and having inserts anyway, there is no downside.

If wanting to use existing, standard head hardware, an insert with a 20 TPI thread would, as you say, no doubt be strong enough.

Thank you TimeWarp and Eddie for the discussion. Very informative.

I made arrangements to meet JComstock next week where I will be delivering my crank and cylinder. We'll discuss your recommendations above.

About the 0.005" copper wire head gasket.............the more I read the more I'm liking it. A little more compression won't hurt anyway as I live at 7500'.
Received an order from Andover; isolastics, swing arm & fork rebuild kit. Be working in that direction

A couple of stupid questions about the swing arm shaft.
Would I be correct to assume that the reason for two flats on the shaft is that this kit is also used on later model swing arms? I think so.
If so, can I install a couple of; https://www.mcmaster.com/6436K39/ drill and tap the swing arm to do the mod?

Brake caliper and master cylinder rebuild kits. Any recommendations?

Pee shooters

Thanks much!
Jerry

Correct, in the beginning only the Mk111 Commando had the flats to suit the two pins as added to the cradle tube on that model.
The flats being across the range of spindles now means the spilt clamp mod can be done utilising those flats.

A bit late but there are two options as far as reducing the master cylinder bore to improve the ratio (Don Pender and RGM sleeve down kits) and both DP and AN do ready to go smaller bore M/C.

I made my own alloy clamps but increased the compression fasteners to 8 mm.

You might consider this You Tube channel which includes the swing arm spindle mod how to and install.
Fantastic channel in general and of course a Mk2a punter.

Mofosheee said:

Would I be correct to assume that the reason for two flats on the shaft is that this kit is also used on later model swing arms? I think so.

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Time Warp said:

Correct, in the beginning only the Mk111 Commando had the flats to suit the two pins as added to the cradle tube on that model.
The flats being across the range of spindles now means the spilt clamp mod can be done utilising those flats.

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Not exactly, as the latest 'long' and 'short' spindles now have the central bolt hole and cotter flats so both spindles are compatible with the pre-Mk3 cotter upgrade cradle (06.6972).

The fact that the flats can be used for the Kegler modification is purely coincidental. The Kegler clamps probably don't actually need flats to clamp the spindle securely.

Mofosheee said:

Pee shooters

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Well... with a (more or less) standard engine, the stock Norton pipes and open peashooters actually seem to fair quite well.

I know you‘re not looking to build a rocket ship, but a dodgy 2:1 pipe of unknown design could throw power and / or torque away and possibly give you carb set up headaches.

In the thread below, Glen tested a pipe designed by a very renowned expert and still didn’t see any gains. I’ve tried different set ups on the dyno and the only set up that out performed the stock peashooters was a high level 2:1 race system designed by Steve Maney, replicas are now made and sold by Brooking 850 on this forum. But even that only made big gains when coupled with increased cam duration (which is what it was designed for after all).

Beware, some peashooters had restrictions or ‘mutes’ in the end that look innocent, but do negatively effect output. At the end of the day, stock pipes and peashooters do perform well, and sound lovely, and most folk like the looks too!

Glens test thread: https://www.accessnorton.com/NortonCommando/dr-blair-on-dyno-hill-place-your-bets.31779/

Brooking 850 made, Steve Maney designed, 2:1 race pipe:

Time Warp said:

You might consider this You Tube channel which includes the swing arm spindle mod how to and install.
Fantastic channel in general and of course a Mk2a punter.

The Mighty Garage

Hi & welcome to my YouTube channel! I hope you will enjoy these videos of some brilliant classic motorcycles & fun projects. Cheers

www.youtube.com

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Yup...........been watching all the You Tube talent.

Fast Eddie said:

Well... with a (more or less) standard engine, the stock Norton pipes and open peashooters actually seem to fair quite well.

I know you‘re not looking to build a rocket ship, but a dodgy 2:1 pipe of unknown design could throw power and / or torque away and possibly give you carb set up headaches.

In the thread below, Glen tested a pipe designed by a very renowned expert and still didn’t see any gains. I’ve tried different set ups on the dyno and the only set up that out performed the stock peashooters was a high level 2:1 race system designed by Steve Maney, replicas are now made and sold by Brooking 850 on this forum. But even that only made big gains when coupled with increased cam duration (which is what it was designed for after all).

Beware, some peashooters had restrictions or ‘mutes’ in the end that look innocent, but do negatively effect output. At the end of the day, stock pipes and peashooters do perform well, and sound lovely, and most folk like the looks too!

Glens test thread: https://www.accessnorton.com/NortonCommando/dr-blair-on-dyno-hill-place-your-bets.31779/

Brooking 850 made, Steve Maney designed, 2:1 race pipe:

View attachment 19956View attachment 19957

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About the Pee shooters. Please don't take offense. It's about my twisted sense of what looks appealing.
Those look like my XR pipes. IMO very nice
JC's Norton sports a homemade set of 2 into 1's

Might have to roll my own set of pipes; https://www.coneeng.com/harley-davison-mufflers.html

Yeah but JC knows what he’s doing! I just wanted to make sure you’re aware of the likelihood of negative performance impact.

Also, have you seem the S type and SS type systems ?

Understand. Probably shouldn't go down that rabbit hole. I know JC has the apparatus to quantify the performance of his mods.
Personally, I never liked the pee shooters and thought they were a problematic. Prefer something simpler, lighter, with less pipe and mounting hardware (if it exists). The Dunstall pipes that came with my bike are severely rusted.

Yes, I've seen the S and SS systems. Nice. My friend has some version of them on his P11.
Jerry

Jerry,

That 2:1 pipe looks like a BUB pipe.

I have a BUB pipe on my P11 that is similar, but mine is a one off built for a straight up motor. It makes power everywhere, but took a lot of experimentation and modification. When the pipe was configured like the one in your image, the top end performance was weak. Nice around town, but that was all it had. All things considered making it work is probably more tuning nonsense than you may want to deal with. A stock dual exhaust would work like it should without redesigning anything.

However, I'm sure there are people out there that are happy with the BUB pipes as they come. Not I.

I know nothing about that unobtanium pipe Eddie has on that Blue Norton, but it is a beautiful piece of work, and I would imagine works well with those Keihin FCRs and everything else in that motor.

Schwany said:

I know nothing about that unobtanium pipe Eddie has on that Blue Norton, but it is a beautiful piece of work, and I would imagine works well with those Keihin FCRs and everything else in that motor.

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It’s a copy of the pipe designed by Steve Maney. Made in NZ by Mike aka ‘brooking850’ on this forum, as far as I know he‘s still making them.

Its very well made, definitely worth contacting Mike if you want to go a bit ‘hot rod’...

Fast Eddie said:

It’s a copy of the pipe designed by Steve Maney. Made in NZ by Mike aka ‘brooking850’ on this forum, as far as I know he‘s still making them.

Its very well made, definitely worth contacting Mike if you want to go a bit ‘hot rod’...

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Thanks for the info on the pipe. I thought it was a Maney pipe. I must have missed the "copy of Maney" part when skimming though the thread. Oops

My modified BUB pipe actually does work well. Unfortunately, it's exceedingly noisy. I have a feeling I'm going to need to do something about my tiny brakes before looking into another exhaust, but will keep Mike in mind.

Schwany said:

Thanks for the info on the pipe. I thought it was a Maney pipe. I must have missed the "copy of Maney" part when skimming though the thread. Oops

My modified BUB pipe actually does work well. Unfortunately, it's exceedingly noisy. I have a feeling I'm going to need to do something about my tiny brakes before looking into another exhaust, but will keep Mike in mind.

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Mikes pipes aren’t exactly what you’d call quite! I’m currently running the stock downpipes and peashooters on mine as they’re quieter, and more Commando esque.

Mikes pipe on my Commando is no more noisey than my Ducati with Termi's.