Crack in cylinder head when tacho gear removed

Ready for paint:

In the military we used "Smooth-On" Metal Set. It is much better than JB weld. It was the only e-Poxy allowed to be used on aircraft hot areas. Metal Set is much better than JB Weld. JB Weld is Iron filled and will cause corrosion on Aluminum and fall off at high temperatures. Metal Set is Titanium Oxide filled and is designed for this kind of stuff. I used Metal Set on quite a few engine cases and they held indefinitely. BUT I don't know if I would trust an epoxy in the hottest area of the engine. I would either solder it with Zinc sticks or have it TIG welded. If you loose that chunk while on the road you can loose most of your oil. We all know that this stupid thing always leaks, even under the best of circumstances. How much do you think it will leak with that chunk missing on the road?

Well...we will find out this summer if it holds up or not.
There is no stress on this area, might get a bit hot but it´s still quite far from the cylinders.
Will fill with liquid gasket before I put the tacho-drive in and hopefully get it sealed.

Is Metal Set available for civil use ?

I wouldn´t get on a plane where engine parts was fixed with any chemical weld

If you put liquid gasket in the drive before you install it, you will never be able to remove it.

You got a point...
But how get it sealed otherwise...? The O-ring dont do muck good..

I dont see a reason to get the tacho-drive out again unless the drive-screw wears out. And that will take a long long time.

Even considered putting some JBWeld in when I do final assembly...that will get it sealed
But this is a bit over the top...

Arnold wrote:

You got a point...
But how get it sealed otherwise...? The O-ring dont do muck good..

I dont see a reason to get the tacho-drive out again unless the drive-screw wears out. And that will take a long long time.

Even considered putting some JBWeld in when I do final assembly...that will get it sealed
But this is a bit over the top...

Am thinking the tach drive housing must be removed to replace its o-ring and also the small spring loaded rubber seal inside the housing through which the tach drive shaft rotates.

The o-ring is to prevent oil from escaping around the housing where the housing fits into the head.

The shaft seal inside the housing is to prevent oil from escaping around the shaft.

Would suggest a small dab of Permatex High Temp Copper silicone (from tube -- not spray) at the area where the o-ring can't seal.



Imo, it's important to retain ability to remove the tach drive housing without some super-human effort. So go sparingly as possible with the silicone seal.

The JB Weld repair looks okay.

Good Luck!

Thax for the intel Pat..
Will keep you update about the outcome.

Just have to post a pic of my bike, will look better after this winter rebuild.

Outcome:

The engine head overhauled:

* Valves ground in
* New valv seals
* Glas blastered
* Repainted in black

The head looks really nice, and especially the polished edges of cooling fins.

Good Luck!

Thanx Pat,

Here is one more:

Cylinder before:

Cylinder after:

* Glas blastered
* Honed cylinders
* Resprayed in black
* Polished fins