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Is there a way to stop the exhaust nut coming loose ? On my Camel I have just had the thread repaired because of it coming loose over many years I presume. Even now after rebuild, I have had to retighten the front one several times. Not by much, but enough. I even have lockwire on it !!
I am guessing some type of Locktite would not be good.
So how else to stop it ??
Cheers.

Hi Ross,
Are your new threads aluminium or is the insert snother material? If aluminium, then wiring is probably the best way. It is worth checking the mounting brackets for the silencer aren't flexing as this can cause the headers to move and so release pressure on the nut.
Assembling it dry works for me on the 350s, and retightening when it is hot with light persuasion on the c-spanner with a 1lb hammer helps.too.
Norton twins have the same method of retaining the headers and of course suffer similar problems. One fix for Commando owners is a sort of tab washer that fits into the exhsust nut and is then bolted to the head. Another method used by some is to smother the thread with high temperature silicon sealant, tightening quickly then leaving for 24 hours for it to 'cure'.
A more drastic method used by some is to drill and tap a hole between the fins into the exhaust port and with the exhaust nut tight, a grub screw is then tjghtened against the threads. The risk here is buggering the thread in the head when removing the exhaust at a later date.
Final thoughts- 1/ Are the collets the correct ones for your downpipes? The 350's had at least 3 different types if collet to my knowledge, but I have no idea about the 500 ones and 2/ Are the flanges on the downpipes not worn away from running 'loose'? Again, if wrong or worn then keeping it tight will be harder.
Hope this helps.
George.

The 250T (which is similar to the 500 front cylinder) has special parts to stop the nut coming loose, but they're not available. However it is relatively simple (must be because I've done it) to devise something similar.

Hi Ross,

It dosn´t matter wether you use a wire or screw, bolt or whatever. The most important thing is that you have to rethighten the exhaust nut several times when the motor is hot after you took off the escape. Only then it makes sense to fix the nut. I myself never fixed theses nuts. But after mounting an escape I allways carry the tool for this nut with me for several rides to retight them every time I park the bike as much as I can. After three or even more times you´ll notice that you can´t tight them up anymore. That´s the moment I leave the tool at home. I´ve never had a problem with an exhaust nut getting loose during many years.

norbert

They shouldn't come loose once correctly tightened, but a simple security measure is to use a hose clamp around the nut with the adjuster butted up against the head. On the other hand, if you leave a gap, you can't loose the nut, but you'll see if it's moving.

Thanks guys. Good info there. As far as I know I have the correct nuts. I do tighten it when hot. Last night it was only a tiny bit, so mabey it is settling. I will keep an eye out.
It was a steel sleave fitted.
Cheers.

EVguru wrote:They shouldn't come loose once correctly tightened, but a simple security measure is to use a hose clamp around the nut with the adjuster butted up against the head. On the other hand, if you leave a gap, you can't loose the nut, but you'll see if it's moving.

I use this extremely useful hint on both my 2C/350s. A 350 2:1 exhaust system on a 350 in a 250 frame makes getting the nuts in perfectly trickier and more likely to come loose quickly if the nuts starts to shift at all. With shiny stainless clamps it also looks quite funky in a 'racer' sort of way. For hill climbs I've been known to wire those clamps to a fin. The advice others have given on retightening when hot using an appropriate spanner (I use a an 'adjustable hook spanner') is the most important though.

So I have been nipping up the nut after each ride but there seems no end to it. At this rate I am going to squish the begeesus out of the poor thing. Im not being too hard on it. I do have mechanical sympathy. And I have a hose clamp on it to stop it going loose.
Is there any wisdom in making a soft metal gasket made out of copper or similar ?
What does ye all think ??

What is wrong with lock wire hooked around one of the castlelations twisted just long enough to then thread through a 1/16" hole in the top fin on the head and further twisted for 1/4", cut of excess and tuck under said fin out of sight -neat and tidy? Never had any problems with this and it is unobtrusiv,unlike exhaust clamps, grub screws that mangle threads etc. N.B. Never use stainless steel exhaust nuts, plain steel zinc plated or as original brass or bronze, aluminum and SS interact and fret together so when you wish to undo the nuts it rips the head thread out aswell and never use copper slip also a no no. Ask any aircraft maintenance fitter.

Thanks Harry.
I did lock wire it and then decided to try a hose clamp. The thing is it does not back out or undo at all. It just needs tightening up after a decent ride.
I am hoping it settles. But it is taking a fair amount of time.
I am seriously tempted to get a aluminium or copper gasket made and try it.

i use solid copper for my bikes ( not only the morini)
chosen because that is what i have lying around.
but it works fine

On Moto Guzzis with the same type of header nuts, I use Permatex Ultra Black RTV applied to the threads to help prevent them from loosening. Not only does it keep them in place, but it also makes them easier to remove when the time comes. Never tried it on a Morini though (yet).

Huub, do you mean a solid copper gasket ?

harrymuffin wrote: ..... and never use copper slip also a no no. Ask any aircraft maintenance fitter.

Could you unpack this a bit? Do you mean never use it or not in certain circumstances? And why?Why not?
(Keep it simple as I’m a bit slow on the uptake!)
Thanks

rossguzzi wrote:Huub, do you mean a solid copper gasket ?

yes, just solid annealed copper