I need to fix the right exhaust port because its shot. I've read about all the options and I have head pulled off already. I'm just wondering if I will have to pull the valves and rockers for the machine shop to build up a weld to retap. I haven't asked them yet I figured someone on here would have the best advice.

Wade P

Give Jim a call at Comstock Engineering or call Matt at CNW---they can fix it.

+ 1 on calling Jim Comstock. You can reach him through CNW too. Do a search and see the differant ways it's been done. Jim posted some pictures not long ago of him machining & repairing one. After seeing that I wouldn't even think about it, I would just send it to him. Mine were welded but not cleaned up in the seat area to well. Jim has a better way.

Phil Radford of Fair Spares in San Jose, CA did the ports on a used head that recently bought. Phil's prices are reasonable, work quality is excellent and turnaround time is good. He's a very good guy to work with. Here's a pic of one of the ports. The shot is a little blurry, but you can see the end result. I bought the head from Big D Cycles in Dallas and they said they use Phil for port repair.

http://www.fairsparesamerica.com/

I had mine welded. Not the best way to do it.
Call Phil @ Fair Spares. Great guy. I've been buggin' him for years for parts and advice.

About 2000 years ago early man repaired ports with a BRONZE insert, i think some still do

Jim just did my 850 with the broze inserts. While they are untested to date, they look terrific. I like the idea of not super heating the head.

Russ

Im interested in why no one ever seems to use the helicoil option.

About ten years ago I had both exhausts fixed by helicoil on a 500 SS head on a featherbed race bike. The pipes are off and on many many times in a season and have to put up with race conditons vibration etc. The helicoils have worked perfectly.

Is there a problem using them on Commandos. I cant really see why but maybe Im missing something.

Apart form the perfect results for me the advantages are cost and ease of the fix. You can fix them in place. No need to take the head off. It takes about 10 minutes a side and the helicoil while expensive is not out to lunch.

Maybe its just few people do it. I had mine done in Wellington NZ. The owner had the tap made by a local machine shop (Actually a mate of mine). But the guys not letting on where he found the helicoils maybe that's the issue!.

If you can find someone who can do it I think it is an excellent fix. Half an hour, US$200 - done. Good for 10 year racing and counting.

John

I have been doing the hard aluminum bronze inserts for over 20 years now. Still have not had to re-do one.

I now have a standard thickness insert and an extra thick insert for heads that have had welded inserts so weld build up is seldom needed. The head does not need to be disassembled except in the rare occasion where welding is needed.

The repair is now done in a CNC machine so the fit is perfect every time. I will stand behind the repair as long as I can still operate the machine. Jim 719-646-2610