Graham, .. Starting to work more with Puchs. I have a reliable Airsal 65 installed on a Magnum XK, 15 bing, Techno Estoril and have a good stock Magnum E50 I'll be building for next year. What else can you recommend for the Pollini build you described as far as porting, crank, clutch, bell, gears, head, intake, etc? 50-60% of our riding is open road at 35-55 mph with the rest being stop-n-go in the city. My Malossi LC Hobbits can rip in all those conditions NP but the 65 XK is a challenge for an E50 novice like me when trying to balance good take off and hill climbing with higher end cruising. Durability is a priority as many of our weekly rides cover 40-60 miles+.