Tearing down a 76 MAR and having trouble getting the threaded ring that holds the head pipe to the cylinder off.

I've sprayed it with penetrating oil then hit it with a punch and hammer...no go. Assume it's a right hand thread but didn't want to bash on it too much in case it isn't.

Not only does the threaded ring seem to be seized in the barrel, the pipe itself is loose. Perhaps there's a gasket missing or long since blown out?

Heat and cool it with a propane torch maybe would loosen it up?

Any tips out there?

Sammy Miller Products, used to sell a special tool the remove the ring.

It was not that expensive. I haven't looked but they may still sell it.

Failing that, try In Motion for the tool.

The rings are easily damaged and knocking them round with a drift and hammer may not help.

Yes you are right, anti clockwise to remove.......

There was a rubber gasket behind the header and it did deteriorate causing the header to get loose.

Holden's, the importers, used to advise owners of them when they got old to weld a lugg on the header and another to join them to the right hand down tube to keep it in place and then pack the thread with gasket sealant.

Hope this helps.

Roger Painter also used to do a lot with Ossa's, they may have a tool.

If the cause of the tightness is gummed exhaust residue in the thread, then heating it up will allow it to move

Yes its a RH thread

You will do a lot better with steady pressure rather than using a punch. A "C" spanner can be made from some flat steel, or bought from a tool supplier

Not uncommon for the those threads to be crossed either. You should be able to see if the tube nut is crooked

Thanks guys.

I don't think it's cross threaded from what I can see. Obviously no gasket in it and perhaps the former owner kept tightening the collar to try and compensate. Perhaps one or two threads are visible sticking out of the barrel.

Suspect it's just gummed up with carbon residues after years of leaking and being in there for decades.

I'll put some heat and wrench to it tonight and try again.

get it properly hot then constant pressure rather than a big hammer..

Got it, but pretty much destroyed it in the process.

Heat plus a big pipe wrench did the job.

From what I can tell there was supposed to be a copper washer in between the pipe and the barrel, but there's no sign of one. Wondering if a high temperature silicone o-ring might be a better thing to use though. It should seal up way better and maybe stop the nut from working loose.

I'll put some anti-seize compound on it too!

New nuts are available. Yes never-seize is a good idea. Tie wire is the best way to stop it unscrewing. The nut comes loose because the header pipe moves relative to the barrel a tiny bit in use and takes the nut with it, so a springy o-ring will probably not help to stop it undoing. Yes a high temp silicone o-ring should seal off better than the copper gasket. Compressible composite exhaust gaskets as used on Japanese bike exhaust joints would also be an improvement compared with a flat copper gasket if you can get one the right size.

I don't think even high temperature silicone will handle exhaust pipe heat at the head. Copper is used because it will not burn and it is soft enough to seal. With copper, you should assemble, run things up to temperature to fully anneal the copper then retighten.

For sure use anti-seize on the threads (preferably high temp anti-seize of you can get it). If you have to use a hammer and drift to tighten, do it gradually working your way around the nut.

. Compressible composite exhaust gaskets as used on Japanese bike exhaust joints would also be an improvement compared with a flat copper gasket if you can get one the right size.

Memory a bit hazy but doesn't a TY250 twinshock gasket fit? I'm sure I used one at some point, although a long time ago

I use the 'C' shaped tool for setting the rear shock's, hook it into the hole in the clamp ring and tap the handle round. save's beating round with a drift.

Memory a bit hazy but doesn't a TY250 twinshock gasket fit? I'm sure I used one at some point, although a long time ago

I just checked this and found that a genuine TY250 gasket was a bit too big in OD (56mm) to fit in the OSSA exhaust port (54mm)

2 mm too big? A little time with a file or some emery cloth will reduce the OD of a copper gasket pretty quickly.

2 mm too big? A little time with a file or some emery cloth will reduce the OD of a copper gasket pretty quickly.

The Yamaha gasket is composite with the outer layer being a thin layer of aluminium. It would fall apart if it was reduced in OD to fit a 54mm hole

Been looking on the 'net for the copper gasket and am only finding it out of the UK (In Motion Trials) and France (France Trial Classic.) Being in Canada I'd prefer at least a North American source...if I can find one. Any hints?

What about making one out of something like this?

http://www.autozone.com/autozone/accessories/Mr-Gasket-10-x-10-x-1-16-in-ultra-seal-exhaust-gasket-material/_/N-25w7?itemIdentifier=193863&_requestid=1939033

Also finding some standard fiber-type of exhaust gaskets like this:

http://www.ebay.com/itm/NEW-EXHAUST-GASKET-GASKETS-x2-54mm-OUTER-DIAMETER-ASBESTOS-FREE-FORMULA-/111269337013?pt=UK_Motorcycle_Parts_13&hash=item19e82b57b5

(Also in the UK...doesn't anybody else in the world sell these things?????)

Anybody know if the Ossa gasket is 2 x 54mm or 4 x 54mm?