Joined May 7, Messages 5, I use their oversize exhaust port inserts for Triumph twins and they are very well made. Joined Nov 1, Messages Click to expand Joined Sep 15, Messages Have you considered Jim Comstock's repair? He does very good work, isn't cheap but quality seldom is. John in Texas. N0rt0nelectr said:. Joined Feb 26, Messages What is the cost difference between a good thread repair and new head?
Is the thread problem the only issue with that cylinder head? Something to think about. In my opinion his work is the standard by which all should be judged. Joined Aug 8, Messages 2, Try and contact Ludwig here on this forum with a pm. He did a pretty neat repair on his commando head at the exhaust ports.
Cheers, Thomas. CanukNortonNut said:. He is south of the boarder from me. It is your head and you are just shipping it out for repair. I would inquire about that from customs in your country of Sweden to get an idea of what you would pay for the service repair work.
RGM do a Helicoil for the exhaust threads. Much stronger as it removes the minimum of the porous original casting. The problem is that Roger is snowed under with work as he no longer has a workshop assistant. Another thing to try is to wrap the threaded collar with aluminium foil to pack it out.
You can get the sticky-backed stuff, but the glue will melt and may make a mess! Although obviously I can ask RGM about that myself. HELLO we in east yorkshire have John Malone and sons heavy engineering in Goole That alloy welded my pinch bolt side of the fork leg back up and made a great job for 20 notes and he do any other odd engineering jobs there well tooled up for all types of work, in engineering they even make things from scratch , yours anna j.
Anna, thanks for the tip. Without wanting to teach people how to suck eggs here, may I offer some advice. I've had two heads fitted with aluminium inserts and they haveboth worked a treat. When I fit exhausts I do a dummy run first just to get the fit right. Offer the whole exhaust up to the bike and tighten the silencer up slightlyto the pipe so thatany frame mounting bolts will align closely with their corresponding holes.
Tighten the pipe into the head slightly, while leaving the silencerslightly loose on the frame. Once you know that everything will bolt up tight and right, and with the crush washers in, cram the heck out of the exhaust port rose nuts with the Norton exhaust spanner. Doing it this way ensures that the exhausts go into the head straight. Once you have lifted the bike off the ground with the spanner well almost. Now go for a ride, heat the thing up, stop at the side of the road and give them a last heave.
I tried locking wire, springs and all sorts, and everything just kept coming loose. Since I had the heads sorted with inserts and started using my fitting sequence I've had no problems at all. The trouble with locking wire and springs is that they stop the pipes from falling out, but they don't stop them from coming loose. Once they come just a tiny bit loose, they vibrate and wear out the threads, and you don't know it's happening.
The Norton Owners Club Limited. Registered in England No. It wasn't finned so I drilled and tapped M5 holes in the flange so that a long cap head screw could be inserted between the head fins to stop it unscrewing.
This arrangement worked well, lasting longer than the original in years if not mileage, but of late it has needed frequent tightening so I suspected it was on the way out. It finally gave up on the way from Kendal to Applecross. Dan, the late GC's advice is still sound but the combination of alloy head and steel rose nut means that loosening when hot is almost inevitable.
When it does loosen the nut chatters and destroys the threads. If I need a special rose nut made some research is required to decide on the most suitable material. It would be preferable for the nut to 1 expand at the same rate as the head and b be the part that wears out, so much cheaper to replace.
I didn't photograph the finished job but it looked pristine, accurately cut thread and no obvious sign that it had been repaired.
I ordered the nut and spanner to ensure an accurate fit in the newly cut thread but with hindsight a decent standard replacement nut not Norvil's! The spanner seemed a good idea at the time but is a bit fiddley to fit and short on leverage.
I tendthereforeto stick nowwith my standard wrench, although theSeager one would fit in a tool kit and save some burnt leather gloves -- don't ask!.
The advice given so far is absolutely spot-on. You can then wire lock the sealing ring with galvanised garden wire to the cylinder head once you have tightened it whilst hot and it will never vibrate loose again. Mine has been that that for three years now and is solid as a rock. The reason for drilling three holes is only so that when you tighten the ring you have a choice of how long you wish the locking wire to be and to make ease of access when wiring it all up.
Hi Dan Nice description of how to make and fit a new exhaust thread insert and also impressed that you can do the job yourself The only thing that I wasn't too happy with is that you suggest making the insert slightly too long to enable 3 small welds to fix it. Surely the slightly protruding sleeve would be noticed with close inspection and spoil the job slightly?
Hoping you don't mind but as a suggestion I would make the sleeve about mm too short leaving it in effect countersunk Les, sadly not my words but those of George Cohen, thevNorton Doctor. I'm guessing he filed it away after welding, making it too short might mean the weld could be too thick and foul the threads? I have made the jig to mount the commando head in my lathe to turn the knackered exhaust thread out and fit a bronze threaded sleeve so restoring the thread to a better than new material.
If you send me some pictures of your exhaust port i will see if there is enough material to accept a threaded sleeve. Steve Maney does commando head exhaust repairs at very competitve rates and when speaking to him at squires one evening he said to me why did you bother making that jig? I could have but i like the challenge of doing stuff like this i replied! I have just read the late George Cohen's description for alloy head exhaust port thread repair and not wanting to denigrate George in anyway i disagree with his repair method.
I have seen quite a few alloy sleeved exhaust thread repairs start to pull out of the head breaking the welds in the process. The very act of tightening the nut is wanting to jack the welded sleeve out of the head. Much better to screwcut the head to accept an external and internal threaded sleeve.
No chance of the nut jacking the sleeve out then. Hi Peter, your approach to this makes sense.
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