welding combustion chambers

Danno said:

Could Epoxy be used to effect a repair such as this head would require? I know it can be used in intake ports for re-shaping, etc., but can it take the heat of a combustion chamber?

Click to expand...

NO No No :!:

Fast Eddie said:

OK. With all input considered, it seems that head is scrap.

Donate to Hobot, or me, to use as a donor for experimentation and shareing of outcomes to all by doing this: http://www.mez.co.uk/mezporting/bathtub2.jpg

Click to expand...

Head is NOT scrap if you want to keep it :!:

Indecently, this is not a Commando head as it has a spigot.
You could have the combustion chamber lightly skimmed and then the spigot skimmed as well as the face of the head, but you need to find a machine shop who specialises in cylinder head work , that I’m afraid will not be cheap.

I once welded pads above the centres of the combustion chambers of an aluminium Triumph 650 head so I could centre plug it. After I had raced the bike for a while one of the inlet guides came loose and I found the port had cracked longitudinally on the approach side of that guide. When you weld the head, you soften it. You probably need to post-weld heat treat it by soaking in a 100 deg. C oven for a couple of days to bring it back up to strength.

FastEd's bathtube experiment would be the most profitable for all concerned as if made significant joy then FullAuto head molds could be altered to suit and replace after the experimental head decayed too soon. Sipgots put me off as extra work to adapt.

I've often wondered about the bath tub shaped combustion chamber. The closeness to the valve head of the walls of the chamber might reduce cylinder filling ? The reason I think this is because using three cutters on the inlet valve seats actually improves performance. Perhaps a dog-bone shape might be better ?

pistons

The top of the piston on the side that ate the carburetor slide looks similar to the combustion chamber. I would assume there's enough meat on the top of the piston to clean it up if it isn't otherwise worn out. I believe that for original Hepolites (what I was running), the recommended clearance is .0045", what about the ring /land clearance? I'm measuring about .007" there.

-Eric

We have not seen image of the damage and don't hear of valve sealing damage like Peel so likely just sand the thing smooth like Peel and go. Charts show how little a whole point change in CR gives so a little sanding polishing is not much change.

Same link as before, but I've added the refinished combustion chambers. They're not perfect, but I'm pretty happy with how they turned out.

https://onedrive.live.com/?cid=6d60...35&ithint=folder,jpg&authkey=!AHQIVLIXjtFTu4g

I've got the stuff to cc my combustion chamber volumes. What is acceptable variation? It seems like 2% or so. I would assume if it's much more than that I'd try to correct by taking off material evenly across the hemi part of the combustion chamber with a small grinder. The bad cylinder, that I'm assuming has an old, but still serviceable intake valve that isn't a Black Diamond. The Black Diamond valve have a more pronounced hollowing out in the head. I'm guessing it has an extra cc in it. If I were to swap intake valves, when the head has been remachined, but not run would that cause problems? Do they cut the seats and valves specific to each other?

-Eric

Hi Eric.
Whenever my engine has eaten an AMAL alloy slide skirt the resultant zero gap spark plug has alerted me to the fact immediately (almost).
I now have brass throttle slides on order. If they ever drop a skirt...
Ta.

My engine ate a slide twenty years ago and spit it out the exhaust port with pretty much no damage. I was hoping it would do the same this time, won't make that assumption again. I had my slides sleeved by Fair Spares America (Gaylord) a few months after my first slide broke and ran them for 70 or 80k miles no problem. Last time I had the carbs apart I accidentally put an unsleeved one in the left side, hence my recent woes.