I was wondering if 39mm Keihin carbs (with SLP power paks) can be used in place of the 38mm flatsides that are stock? This is for a possible project sled (01 XCSP 600 ves) and i am looking to gain serious throtal response and bottom end. Would the gains if any even be worth doing?

no the factory 38mm flatslides are the best carbs for this sled in stock form. if you want serious horsepower port and throw on a set of 44mm mikuni's. the 39mm keihens are old technology and a waste of time and money

ok thankyou, i plan on modding this sled and possibly using the struther 660 kit. If not, then what would you recommend as far as parts?, id prefer a single pipe and am lookin for tree-tree and corner to corner type performance. I want to get there violently, top end is not important, im planiing on gearing down anyway. any suggestions?

i have heard excellent things about the struthers 660 kits. but to be honest if i were you and wanted a very very quick trail sled then do this: good single pipe such as hot seat ceramic coated or aaen single pipe, full trail porting, slp high flow air box top kit, aftermarket heads, v-force 3 reeds, gear down to about 90mph tops or so, 1.25" lug track, perfect clutching(remember clutching will make you or break you) and wiseco pro-lite pistons coated and boost ported in a clearenced cylinder. this combo will give you a killer trail sled and still be reliable and able to run pump gas. i figure with this combo you would be runnin somewhere in the 134-144HP range which when setup properly can be insane on trails. me myself i dont believe in big bore kits unless i am doing a lot of lake running and dragging. any questions on the exact parts that i would reccomend i would be happy to share so just ask me.