Hi folks, In the search fore more topend power , I've grafted an XL/XR 185/200 head onto the humble postie bike botom end (with an XL125 cylinder sandwich), Although the head was a simple "bolt on" operation, the 22cc combustion chamber volume resulted in a pityfull 6.8 / 1 comp ratio , No probs , I threw some "land fill" aluminium filler into it, reshaping to give me .030" clearance between the head and the XLs Hi comp piston , and managed to get the compression ratio back up to a heathy 11.05 / 1.The new head sports 6mm o/s exhaust, and 5mm o/s inlet valves , compared to the XL100 head it replaced, Inlet and exhaust ports are larger alsoI've had yet another cam built up by Ivan Tighe (399 grind replaces a 356 grind) in an attempt to get some more power below 4,000 rpm , ( less lift,,more duration) an added bonus will be no more polished piston valve relief pockets from things JUST missing each otherI purchaced a set of Serco valve springs, and a set of stainless steel valves are on the "wish list" to slam things shut ,just incase I manage to get the revs up to a clutch hub exploding 11,000+ revsI'm still debating the Methanol route , but it'll be a learning experience, besides,,I may not need it,,,this year