Thanks ......... what I'm building is a vintage racer, so most "street" stuff don't matter, thanks for the imput will "message you" if I get stuck, it looks like a great combination on paper should be "works" power with street reliability (BTW......😡 I helped middle th "Picotte/Feracci" works 888 into a "spl place" .... its the ex: Falapa works bike, fantastic piece of gear) BG
Pompey wroteHi Ben, coming to the end of my build now... You can follow in the thread under projects. I ended up buying a complete st4s from a salvage that had light cosmetic damage only. I was going to sell the bits I did,nt need inc. the frame but it was in such good nick I have decided to keep it and make a track hack. No point in having a perfectly good 851 engine propped up against the garage wall. The short version is I had a complete 851, a complete st4s and just swapped engine, loom and brain from on to another. The main obstacles / changes are
size of engine bolts. I kept the 851 frame standard and just shimmed the smaller 851 bolts with the st4s engine.
The front sprocket had to be re aligned and the fan on the radiator and bottom radiator bracket had to be swapped over to the left hand side.
So I have 2 bikes which will stay together in order to swap out back to the original 851 engine should I want to in the future.
Other then that, away you go! Go luck.
