well yes the head is a 650, it was like this when i got the engine.
I was trying to buy a 600 cylinder head but it was up to 100 E there for makeing the whole project a lot more expensive.
Anyway the goal was to make a stronger engine but with the stadard 600 cc so i could put it in to my 78 126 p, but the rest of the parts could be moded, also, as you probably know the 650 head has a slightly biger exhaust? (not sure now) valves ( 1 mm ) so to use what i have was a double win, 100 E saved and biger valves
im glad that you like it!
So now when i finish my 125p bmw swap i wil go on and start a new 126 engine project
