Part mods…


Continuing the porting started a year ago…


When I was porting the head, I left it outside over a towel… The dog pulled the towel and head on floor!!!



After the 2nd resurface, clean valves…


As the valve seats were a bit deep into the head, there was a very sharp step between the cc and the valve seat, so I’ve machined it to prevent flow losses.


Inlet port straightned also slightly enlarged.



Exhaust port roof raisened.


Inlet valves after a 2 angle regrind, 45º seat and 30º above it.

The left one was polished with 50 grit sandpaper, then 280, 600 and finally 600 with WD-40.



Same treatment here… I’ve polished them not in search of more hp, but to prevent carbon adhering so easily.



Same thing to the exhaust valves… Not so polished because the steel is much harder compared to the inlet.



Note the lightened piston. I’ve managed to take 4 grams out but it still remained to heavy compared to rest of the pistons (weight in grams with the gudgeon pin)…

I’ve put them in order so that the rotating equilibrium is not very disturbed by different piston weight’s (not the order in the pic…)




About 600g were taken out of the flywheel (400g near the ring gear)


Ground and polished crank (fillets respected)