Exhaust nuts and sealing washers (2016)

A couple of questions, if I may. 1973 pre-MkIII Commando, 850, fitting new exhaust headers, with new seals and tab washers. I'm fitting part nos 063375/6, the 750-style headers without the balance pipe.

1. The sealing washer has a rounded side and a flat side. Which way round should it go?

2. When I tighten the finned lock rings, there's a bit of a gap, about 3-4mm, between the shoulders of the lock ring and the head. The tab washers have a bend in them but there's still enough room for them to rattle a bit. A search of the forum suggests I should put an extension on the lockring spanner and tighten all I can, then repeat several times with the engine hot. Presumably that flattens down the sealing washer and allows the lockring to fit more snugly to the head. Is this the right approach?

Thanks in advance.

You're on the right track. Throw away the rattle rings, they do nothing but hide a loosened nut. The gasket isn't really specific which way, but I fit the flat side to the aluminum head for general purpose.

Flat side of washer to the head, rounded side to the flange in the header pipe so that you can get a tight connection. Loosely assemble the whole exhaust and tighten 'as a whole' to get a 'natural' run. Use the correct C spanner, hook onto the bigger petals of the exhaust nut & heave away until it's solid; just keep tightening it up when hot after each ride (or at your coffee stop during your ride) - until it passes muster without adjustment a few times (then check it regularly).

I don't use the tabbed washers either & I've never experienced the loosening problems that others have reported (well not yet anyway :wink: ! )

Mike, Mk III

Tighten with engine running 3000rpm, acts like a big rattle gun

And do this as well , makes use of the tabbed washers, although I cut the tabs off.
Regards Mike

I find some high temperature RTV on the threads works well.

I retighten a couple of times while hot and then it stays tight pretty much for ever.

And Bronze nuts also helps as it rate of expansion is nearer aluminium than steel.

Bronze nuts are very good , albeit a tad ugly with oxidations. I've learned to use copper RTV. high-temp silicone , smeared all over those preciou$ exhaust threads. I buy Honda CB 350 copper exhaust rings and smear them in RTV. before fitting , although the stock ones are good too. Use special wrench to tighten. BMW airhead wrench is even better. Then fire her up and shut down after a couple minutes , then tighten again. Then go for a short ride , let idle back at base , then tighten again. Go for a long spin then repeat. I use a 5 lb. sledge to the tool end. Never use a retention ring ( unless in a show or Concours display )as they only allow back-offs to rattle away at preciou$ threads without you noticing until too late. Best issue here - is the exh. screw falls out , then you will hear and know what's going on. That said I've NEVER had the exh.rose nuts back out ever following this. Good riding to you.

Brooking 850 said:

And do this as well , makes use of the tabbed washers, although I cut the tabs off.
Regards Mike

Click to expand...

I like the look of the ring on the non oem ring. Is that something on the market or a personal fab?

Never seen a ring like that. Why ?

The rings are a standard Norton part (tabbed washers) i cut the tabs off the washers , drill and tap the exhaust nuts and you can use the grub screws to tighten against the ring washer so it doesn't leave divots in the head.
This is done after heating the motor and tightening the exhaust nuts.
Regards Mike