I thonght that slider comment would flush someone out Curley.I sypathize with ya 2-valver,these bikes generally don't come together in week and to have the goal posts move IS disappointing.The only class 4 ya 2-valve is pre 75 solo 263 and over.Thats what we did in the day.The Nats up to 98 was that way.I traded blows with Tony Day that year 4 the title, with the result hanging till the last round.I'm positive Col Moody,Billy Uns,Grasy an co would love to see the mx vs slider matchup, as was featured pre 75, Gall, Willing(len),Scaysbrook(CCM),Ron Davis,etc vs slider mob.Having ridden a fair slice of pre-84 sliders,as anyone who has will tell ya(and you already know Curly), the 4-valvers made 2-valve speedway engine obsolete overnite.Just lookin @ entry form, why not Pre-75 4-stroke All Powers.BSA has to be pre-70 does'nt it?