Exhaust port repairs

On my build, the head I am planning on using (RH10) needs the exhaust ports repaired. I know where to get it done, but I am looking for a different way to do it. When I first joined, I remember seeing pictures of someone who has done such a thing but I can't find those pictures. If anyone has pictures of a repaired exhaust thread, or repaired head with exhaust pipe in place or not, I would appreciate it very much. The pictures can be posted as replies or sent to me at jeandr at videotron dot ca

The head I have was over bored for an insert which looks like it has 13 threads per inch. I can make inserts that would fit the head but instead of having the large finned nuts, I would use a sleeve held in place with a bunch of screws (most likely 6).

Jean

Hi Jean

That can be my repair, have a look here
http://accessnorton.com/norton_commando ... highlight=
if you have question I shall be glad to try and help you.

Best regards
Henrik

My head has had bronze inserts fitted,it was a nice job 10 years ago,the head was bored out and the insert was a 5thou interferance fit in the head.The insert is steped internaly and externaly.Then 4 4mm by 19mm countersunk srews are fitted in through the bottom flange to stop it turning,but one insert has come loose,screws poped heads off so had to be drilled out unfortunatly i believe one of them was hiding a fault. The screw hole had gone through to catch the bottom of the spring seat,after reparing oil started leaking out of ex port,was not a happy camper as I had just fitted new piston and thought I might have had a mishap. Its amazing how far a small drible of oil can go.I think it is time I to try and find another pile of alloy rocking horse excrement :cry: :cry: :cry:

Lucky said:

Hi Jean

That can be my repair, have a look here
http://accessnorton.com/norton_commando ... highlight=
if you have question I shall be glad to try and help you.

Best regards
Henrik

Click to expand...

Henrik, YES, that was the one I remember, I will take a good look at the pictures. Did you do the work yourself?

Jean

ludwig said:

My solution :

Click to expand...

THAT is a very good solution, looks like it will not strip or come loose no matter what. I am thinking of something similar only I have to make an insert to fit in the head, so I may as well make something different than using the regular finned nuts. Something like you did with a round alloy or stainless steel insert would look good as well as not come loose.

Jean

My repair consisted of an overbore, fitting of an alloy sleeve which was welded into place, and that sleeve tapped in the same thread as the stock pipe retaining rings. The tapped sleeve has a shoulder at the bottom of the hole to prevent the possibility of the exhaust pipe jacking out the sleeve.

I like it because it is an unnoticable repair and cost $230 for both ports.

I'd post pictures, but the server is down where they're posted right now.

This is what I have to work with, the threads are 14 TPI and as you can see the hole is pretty big. I can make an alloy insert which will thread in the head, then make all the other pieces to hold the exhaust pipes securely.

Thanks for the ideas guys.

Jean

Jean,
My port looked identical to yours. It was bored out, tapped and sleeved with a threaded steel insert, like a solid helicoil.

Completely invisible, no screws, no problems in the last 5 years. Herb Becker did the work.

Not finished

Finally got some time to work on my bike today. Here is a picture of my exhaust port repair. I made a threaded sleeve and I will make another mating part to hold the exhaust pipe with the six screws. I will use some epoxy to hold the sleeve and fill in the gaps, then I will drill the holes deeper in the head to prevent the sleeve from ever trying to unscrew itself (the screws will be half in the sleeve and half in the head). Then I will use a grinder and match the head's exhaust port to the sleeve. Although it looks like there is a big gap from the sleeve to the head, it is only a mismatch between the round hole I machined and the port shape which is not quite round.

Jean

Finished

Here it is finished. I will try some hex head bolts (I have a bunch on 6mm SS bolts), if they look right that is, otherwise I will have to buy some 6mm hex heads longer than the ones I have on hand.

Jean