Loose header pipe

I have a loose header pipe on my drive side, 72 Commando. The assembly on the inside consists of a thin washer and a cone shape piece that fits inside the bell part of the pipe. On the outside I have a lock tab washer and then the main star nut. The star nut was very tight against the tab washer and head. I have the right wrench and tightened it while hot. But the header pipe can still be wiggled around. I'm thinking if I don't use the tab washer the star nut will bottom against the bell end of the pipe better. Any reason why it could not be left off. The head and star nut are drilled so that they can be lock wired.
The problem is that the port has been repaired and has weld around the outside margin stands a little proud of the original face.

Not all exhaust nuts were created equal ,some years had fewer threads,some more. You want threadage (more) to compensate for the proudness of the aluminum welding. All those retaining rings and drilled lockwires and split collars and stuff work against your happiness.

htown16 said:

I have a loose header pipe on my drive side, 72 Commando. The assembly on the inside consists of a thin washer and a cone shape piece that fits inside the bell part of the pipe. On the outside I have a lock tab washer and then the main star nut. The star nut was very tight against the tab washer and head. I have the right wrench and tightened it while hot. But the header pipe can still be wiggled around. I'm thinking if I don't use the tab washer the star nut will bottom against the bell end of the pipe better. Any reason why it could not be left off. The head and star nut are drilled so that they can be lock wired.
The problem is that the port has been repaired and has weld around the outside margin stands a little proud of the original face.

Click to expand...

Are the threads worn inside the head? If so, it sounds like you may be ready for bronze inserts.

No the threads are in good shape and these are the longer 750 nuts. The problem is with nut tight it is not bottoming against the bell of the pipe inside the port.

Do not use the lock tab washers but for decoration only. You must remove what prevents rose bolt from seating on the header flange. Most the simple as pie 750 users end up w/o anything that can crush down over time to releve thread locked clamp force or the vibes turn Al threads to dust. if a spacer washer must be placed in front of the rose bolt it should be decent hard steel. The seal comes from flange seating and threads not by the crush washers. Lock tabs can not prevent clamp force loss, only brutal force torque shock methods best done hot of course. Greasy silver anti-seize works though excess melts out. I've been pleased last few removals with Milk of Magnesia like jet engines use. Safety wire not bad id to prevent loss on the fly but that's it so back to grunt and groan he man with a cheater bar or bash and bang on factory claw like a lazy shade tree never forcing nothing by big enough hammer.

might be a ghetto fix...but i'm trying to think of a reason it won't work.....but if all else fails...double up on the copper crush washers?

Sounds like you have MKIII pipes/spherical seats... But maybe missing split collets, (item 32) http://www.oldbritts.com/nor_mk3_75_26.html

Or do you mean "Flange" rather than "bell part" of the pipe?

Copper is famously softened by heating to level exhaust does so a no no d/t it crushing down over time losing thread locked clamp force and ending up needed a repair, if not caught in time or re-nipping after each ride. Likely fine though if ya do the water jacket and radiator modification. On both my '72 the ring bolts nip up on head flange with no washer inbetween yet leaves a few threads short
of rose bolt fin area touching the head. Make sure bolt runs full in w/o header of course.

I run aluminium/asbestos crush washers from a Suzuki (I think). Never a problem. They are thicker and stronger

Bolted it back together without the tab washer. Everything seems tite. There is about a thread or so showing on the star nut. We shall see what happens next ride. Just waiting on it to cool off a little bit here. Seems like Sept is always our most miserable hot month. Thanks to all for the replies.

concours said:

Sounds like you have MKIII pipes/spherical seats... But maybe missing split collets, (item 32) http://www.oldbritts.com/nor_mk3_75_26.html

Or do you mean "Flange" rather than "bell part" of the pipe?

Click to expand...

This absolutlely sounds like the issue to me too. If you have a thickish steel convex washer in the head, and a bell shaped header that it nests into, you need the split collets that go into the big exhaust nut to lock the whole assembly together. You may also need the MK3 chrome plated cast iron nuts. Forget the stupid lock ring.

Say What? The bike is listed as '72 which should have simple screw in ring bolt 750 of style. Strange if someone went to trouble to fit 850 head on. Suzuki washers have been used for couple decades if it don't seal up well like mine have w/o them.

hobot said:

Say What? The bike is listed as '72 which should have simple screw in ring bolt 750 of style. Strange if someone went to trouble to fit 850 head on. Suzuki washers have been used for couple decades if it don't seal up well like mine have w/o them.

Click to expand...

I'm possibly wrong but pretty sure one can put any type header on any type head with the correct hardware for the pipe being used. No?

I may have been a bit confusing on the first post. After taking a good look there is no cone shape piece. There is a flare with the end of the pipe inside it. It bears against a copper washer inside the port. I believe it is definitely the 750 style.