Polini 177ccm

I am planing to put polini 177 on px 150 with electrostart. My plan is to put polini177(14000800), longstroke crankshaft(46000000), carb from px200(400000T7) and simonini racing exhaust(40307000). But I'm not sure about gears and clutch,do i need to change it? Also do I need to modify engine casing to fit the cylinders? What else will be good to change?
Thanks in advance

Hallo. In order to use your polini 177 with longstroke crank you need the cylinder head packing 1.5mm; besides, because of a well known problem of the polini 177 head, you have to: either add an extra cylinder head packing 0.2mm (losing a little bit of torque), or buy the MMW head (which on the contrary improves performance). About the carb, you need the floater chamber cap for 24/24 with 5.2mm needle in order to avoid lacking of fuel at maximum revs. The exhaust is nice but I would prefer a sito plus because it reaches almost the same high revs, althoug more gently, but has much more torque at low revs, but this choice depend also on the gears you choose. If you want an engine with not very high top speed but reached very quickly, engine which can easily climb hills and which has no trouble if you have a passenger or lagguage, than you may keep the original gears (21/68) or, at maximum put a z22 (sip indicates this article for the piaggio z65 of the px 200 but actually it works better with your z68); remember that you can add the z22 also after having tested the engine with the original gears, because it is an operation that does not require the opening of the engine casing, you have only to remove the clutch. If on the other hand you want a turistic engine, able to reach higher speed even if not very fast, than you can put the 23/64 polini or the 23/65 piaggio (px 200), and in this case I would prefer the sito plus than the simonini. Clutch is better with 7 springs (px 200).

The cylinder fits perfectly, but the original ports are much smaller, so because you will have the engine casing open, enlarge the ports in order that they coincide with the cylinder's ones. Besides it is good advice to obtain the maximum performance, to enlarge the valve. Oh I was nearly forgetting: the venturi of your carb 24, the hole of the carb box and the valve have to coincide so remove the "steps" (because the original carb box and valve are for the carb 20).

I hope to have been helpful. Cheers. Oscar