Yes they are and as far as using the appropriate pistons(which cost $300 A POP) with the Lilly head to take full advantage of the special Squish chamber then "NO" there is no one on this site that I know of.If you have very deep pockets and plan on racing the XS go for it but for daily street operations the XS head with a little attention to detail will flow better in the lower lift spectrum where's it's need for street use for a lot less money. If you can get a hold of the early XS head "70's" they have better uniformed intake and exhaust ports to work with. The flow curve of the XS has the inherited tendency to spike early then diminish rapidly off causing the port to stall at higher lifts and this is where the Lilly shines allowing increased breathing at higher RPM's over a street ported head( but with some good old JBWeld the stock head can be reworked to bring that XS alive) ,never port for maximum gains,port to the cam if possible.Who's got one?
Has anyone had any experience with these heads? are they as good as they claim? Worth the money?
Your welcomeThanks for that info, the engine I am building will be a racer. what are the options for the pistons? who makes them?
some info you'll never be able to searchDo a search for Harry Lilli replica CNC head, and Harry Lilli yamaha. A lot of interesting info comes up.
We've shipped at least five CNC heads to racers in Australia and New Zealand. If you ask around I'm sure you'll be able to get first hand info about whether they feel they obtained sufficient bang for their buck.
In reference to Jack's previous comments, I agree the head is overkill for a street bike (although Tony Guest's tracker is very cool with 68 RWHP and great "streetability"), however I don't agree that the Lillie porting is substandard at less than upper RPMs. I offer as proof both the street user-friendliness of the Guest bike and the fact that Steve Eklund won the Peoria TT - a race where only a very small percentage is spent at high RPM and wide open throttle - with this porting and 34mm carbs against the best AMA pro-level bikes and riders.
dwyatt, send me an email and tell me about how China is going.
Craig