I have only used Tecumseh HS40 and HS50 engines on my bikes. I was wondering if theres a any advantage to using a H50 OR HH50 engine. I know you need to have a frame big enough for it. I know Rupp used big block Tecumseh's on the 68-69 TT-500 and Roadsters maybe others models. I run across H50 and H60 from time to time but I never have picked one up. Do they have good performance?