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Does anyone have a pair of 350 exhaust collets that they would be willing to sell?

Are you talking about the half moons?

There are different models depending on the collars of the tubes!

So basically it is probably easier to make some up on a lathe

Make your own? If you have lathe and material, then yes.
As Norbert says, there are to my knowledge 3 different shapes of collet for the 350.
If you make your own, pay attention to the in-head seat shape as it isnt flat, and that curvature/angle should be matched with the collet.
Regards,
George.

Instead of making them as halves, some people prefer a full ring.
It has to be said there are some advantages and some disadvantages. We use the complete ring type on our 350s.

Gary&Anne

How do you get a full ring over the collar of the tube?

norbert

I was wondering the same. I thought the split collets allowed the removal of the nuts.

Some exhaust pipes split so complete collars could be used by feeding them from the other end of the downpipe. I have what seems to be an old Gazelle 2-1 exhaust (oldies might recognise the brand) that came with a bike where that's entirely doable. It's the one where the rear head insert came out of the head of that bike and they both disappeared under various vehicles' wheels on the M40. I found the battered downpipe, and swapped the head and the exhausts for the standard 2-2 ones.

At some point I'll remake a better rear down pipe and would then be able to make suitable collars, etc. (yes I have a mediocre Clarke 300 lathe, given to me as it wasn't used and needs fettling too)

This only can work if you dont have an interferrence pipe between the tubes.

Often, not allwas I wonder how they managed to pass the nuts over the collars of the 500 tubes, because they are caught between collar and interferrence adapter without a posibillity to get them off. Well, you allways can file down the collars, but how did they get there

norbert

The 'racer' 2:1 system has welded on flanges and does not require collars or half rings. That is 2:1 though so the 'nuts' can be fed on before the system is assembled. A little fragile as with a 350 in a 250 it's all under a bit of train, so I have had to beef up the welding once. Luckily stainless arc rods were up to it. "You can't see the join" so strength prevails over neatness.

The road 350/2C uses the stepped half rings if wearing the NLM 2:1 system. That's with Kanguro heads.

Some exhaust headers allow the use of full rings. Others require fully split collets or a full ring with a single cut so it can be wiggled over the end of the pipe. The split collets are a great solution. Also worth considering the main advantages of rings instead of collets is (1.) they align into the exhaust nut rapidly and (2.) if the nut comes loose when you are out on a run you don't lose the ring like you would the collets. p.s. lockwire the exhaust nuts it's less damaging to the threads than the "very tight" option.

That´s a good point!