Maybe the chemical metal will do the trick and you have many km ahead before you will have to tackle the problem.

I used chemical metal on pushrod tubes in 2011, and it's still working. Applied it all around the tube, but I think it will be fine just as a spot patch since you're head is mounted to the engine. But the bigger area it is applied to, the better. Make sure the rod is totally clean, and rub it down with fine abrasive, before applying the chemical metal. The engine has not been used much until this summer, but all seems fine. No leaks. I consider it a permanent fix.

A pushrod tube suffered a major leak (the hole was/is absolutely tiny but obviously very high pressure) and I used exhaust paste/putty as "stop gap." It's still oil tight three years later. I did buy a tube of chemical metal to do a "better job" but as the exhaust paste is providing an oil-tight seal I'm in no rush to disturb it.

Thanks folks !

Materials ordered for repair....I found a post by Ken H, from 2011...



15 years will outlast me

I'll take some pics when its done.

Did the cooling shrouds touch it?

the hole is nearer the bottom of the tube so a couple of mm clearance for plate and clip,,,,,I've been out tonight and cut and shaped the patch. hopefully the Araldite here tomorrow.

Also, found a perished fuel pipe at bottom of pump, so ordered some ethanol resistant pipe to replace it while its accessible....

The hole



Cleaned up


The patch


The gunk


Patched and clamped

Fingers crossed

Well, seems to be oil tight Ran engine till hot and all seems well

Put it all back together, and put the seat in..... out blinking into the sunlight under her own steam for the first time in 12 months ....

Tracking and try to get exhaust sealed tomorrow

Woo woo ... thats progress