A good rider on a 400 should be able to beat some GP250`s.
My mate Neil Petford came 2nd & 3rd at Croft in the open GP class on a ZXR400 in 1996. It was a New Era meeting, so had quick boys racing there. Was just after I`d retired from racing. I remember it was embarassing when Brenda Scyvier ( think that`s how you spell it), came over & apologised to Neil. The 250 boys had complained that he`d been awarded trophies meant for the GP250`s. Made me laugh when the riders came over to take the trophies from Neil, he told them they obviously deserved them, after being beaten by a pretty much stock 400 road bike!
He was bloody quick though, the git always beat me!
I was going through a funny patch, also was using Michelin TX HI-Sport road tyres which a sponsor supplied free but were sh!t. Switched to Dunlop inters for the next year & started to get my confidence back. Went faster in the damp conditions at Cadwell than I did in the dry with those shite tyres on. Would be nice to race against Neil again & see if I could hang on! Funny but, I`m faster now than I was then. Got my head sorted.
Anyway, he still holds the 250 lap record round Cadwell full circuit (before they put the new chicane in), when he won the Steve Machin Trophy race. Beat a £40,000 Aprilia race bike on his TZ250A, same as I had. He always was a nutter, still is!