do i need exhaust collets?

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alan hodge

alan hodge

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gentlemens I am ready to put the 1973 engine in 1972 frame on my commando project...I will use unbalanced exhausts do I need the split collets or just the copper o ring gasket things or both?
many thanks
 
thanks commando...750 pipes will work correct? threaded part of my exhaust nuts and exhaust port is 5/8"
 
You need the 750 exhaust nuts .72" threads. They have a longer threaded section than the 850's which are about .62" to leave room for the collet. Yours sound like 850's at 5/8". The thread will stick out of the head a bit. You want the nut to bottom against the pipe flange in the port, not against the front face of the head.
 
thanks htown16...well..i have 850 nuts if I understand I need to make up a bit of gap? 2 crush washers per side perhaps? surely everyone who uses unbalanced pipes on 850 engine does not buy new 750 nerts...thanks again
 
I keep the spherical seats as this allow even the 750 pipes orientation to be adjusted especially the timing side one for kickstart clearance, they also allow the use of the 850 nuts but I have gone to 750 bronze ones for less likelihood of loose nuts.
 
kommando said:
I keep the spherical seats as this allow even the 750 pipes orientation to be adjusted especially the timing side one for kickstart clearance, they also allow the use of the 850 nuts but I have gone to 750 bronze ones for less likelihood of loose nuts.
Click to expand...
what s spherical seat? commando I recognize you from britbike site I am RAF940 there
 
i guess i am dancing around the main thing..what i need to put unbalanced 750 pipes on 73 850 engine..thanks for your patience
 
kommando said:
The balanced pipes had a spherical seated washer as the first item inserted in the port the ends of the pipes had a tapered end which when pressed in by the nut sealed on the spherical seat even at an angle.


https://andover-norton.co.uk/en/shop-drawing/147/exhausts-mufflers-passenger-footpegs

see part 31
Click to expand...

That's 850 Mk3.



The original 850 balanced pipes were 063997 & 063998 with 063988 lock rings, 063990 collets and 063995 sealing washers.

850 Exhausts, Muffler, Mutes, Passenger Footpegs
(1973)
https://andover-norton.co.uk/en/shop-drawing/194/850-exhausts-muffler-mutes-passenger-footpegs#

However, the original pipes aren't available from AN at present so they've changed history once again by linking to the 850 Mk3 pipes that require the Mk3 spherical seatings.
 
alan hodge said:
I will use unbalanced exhausts do I need the split collets or just the copper o ring gasket things or both?
Click to expand...

alan hodge said:
i guess i am dancing around the main thing..what i need to put unbalanced 750 pipes on 73 850 engine..thanks for your patience
Click to expand...

That may depend on which pipes you buy as both 'flanged' and 'flared' unbalanced pipes areavailable.

"Link broken"

"Link broken"

The 850 "Mk3" flared pipes were not originaly made in unbalanced form.
 
Last edited by a moderator:
I know its MK3 but they were fitted to MK2A's as they were on my bike with its original balanced exhaust pipes which are not MK3 but MK2A. As it is the spherical seats work with both types of pipes and because the spherical side faces out and on the 750 type the spherical seat catches the ID of the 750 flat flange.
 
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kommando said:
I know its MK3 but they were fitted to MK2A's as they were on my bike with its original balanced exhaust pipes which are not MK3.
Click to expand...


Yes, also late Mk2A but not 850 Mk1 which is why alan hodge apparently hasn't got, and doesn't know about the spherical seatings which was the point I was trying to make.

Edit;
The AN Mk3 drawing and also the original parts book has the collets and spherical seatings drawn/listed incorrectly as "31" (nearest the pipe) is the collet and "32" is the spherical seating.
 
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So you have 3 choices

1. As per 750 parts, long nuts with the ring sealing washer in first.

2. As per 750 with extra sealing washers to pad out allowing use of short nut.

3. AN 850 MK3 Spherical seat with short nut.

All will work as I have used all three but I now use 3 with the long bronze nuts.
 
i understand now...thanks very much for everyone's patience i am used to BSA/Triumph this is my first Norton build..an interesting education...
regards
 
pipes came and I used one black steel washer in each port....tightened nuts up hand tight and had a little over a thread or two showing...pipes perfectly tight no wiggle..will finish the job with strap wrench....plenty of room for kicker/exhaust pipe clearance...pipes are from emgo by the way...........
 
Good but a strap wrench will not finish the job. Buy the special tool to tighten up the exhaust rose nuts. Use all your strength. Then fire the bike up and go for a drive. Then use that exhaust wrench again , hot.
 
Torontonian said:
Use all your strength.
Click to expand...

Unless you are physically challenged, I would have to disagree with this. If the threads in the head and on the roses are clean and straight, you only need to get them tight and then retighten after heating. Going Mongo on an exhaust nut wrench sounds like a prescription for exhaust thread repair. I've never stripped one yet, but sometimes I carry the wrench on that first ride after installing exhausts.
 
I think the thickness and material used in the crush washer is important.
Rolled copper washers used in Hondas will last for many re-tightens.
I've also seen stainless steel.
I'm not familiar with a black washer as poster described.
Seeing a few exposed threads on the threaded ring after tightening is normal.

Just don't use a punch and hammer (or rock) to tighten. Like some did back in the day!
 
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