i know it's a old thread and all,but i did notes some concerns about your build jeff. the flywheel off the vertical lawn mower could be to light for your project build. running that centrifical clutch could be little to heavy and unbalance piece for that very light flywheel to absorb. very good chance you could get a unwanted vibration from that setup. personally would just bolt on the cast steel flywheel and go. and has a option you could mill down the finn's little. that would help on the excess weight spinning. still enough to asorb the heavy clutch spinning on the other end of the crank. also installing a hot coil will make a big difference. maybe 245 cam. hey i'm just saying because you already have the mikuni style carb and header...:shrug:connecting rod needs to go by..by too. the older hs-rods like them are weak too. the newer ohh rods are strong,but a billet would be the best....:thumbsup:
under cutting the stock valves maybe a problem too. if i am correct the factory valves are made up of two pieces fused together and where you under cut them is where they are fused together.
what was the bore size? something like a 4hp bore or smaller? if so, you could of tried a hs-40 crank in that block. i believe the counter weights might be smaller? might help on your clearance. also the newer pistons come with a thinner style rings that might help little on less drag on the cylinder wall and there is different options on aftermarket valve springs and retainers...:thumbsup:
i too would like to see it done jeff….:thumbsup:
if not then maybe this winter i will build one.....