Sylinderhead repairing

Original AYA-10 singleport heads were absolutely too much planed, and thatfore I face much problem when rallying with this engine back 90´s with USK-13. When you lower heads too much, it happens that watercanal doesn´t have enought strenght/material and it will bend. This causes sylinderhead gasket burning. I solve that problem, as student that time, by using fuel oil as a coolant. So it doesnt matter if coolant went to oilsump. Just after rally scrutereening, and right before rallystart we made oil change. Thatway engine works, and doesnt break out. Just poormans racing.

Later on , I change heads better ones, but same time the engine loose much power . So I liked to rebuild the original AYA-engine also with those ”too much planed” heads. Solution is sharp welding to the water canal. This is one good secret how to get long mileage to our V4. If you cant welding, dont do that. Otherwise you can destroy your heads.

I also like to know whats the comression ratio, so I measured combustion chamber. Result was 31,5 cc. I also calculate how much sylinder head gasket higher total volume and it´s  whole 10 cc, I find out that total volume is round 41,5. Thats because the engine is made so that pistons doesn´t go over deck. Actually there is room for piston go over deckheight, but this is old engine, and I will keep it traditional. After that it was quit easy to calculate total combustion ratio to the engine with 1,5 litre cranksaft/58,86 stroke and 92mm bore/flat pistons. Result was 10,43 : 1

I really like to feel if this construction rebuild works as it should.




Written by Tikkis

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