gs400/425 compatability with 450.

[herbie 1964]

 :dunno_black:Hi guys, I'm in the UK and am looking at a long term project,there is a race class here in the classic club for pre 81 aircooled up to500cc bikes, my thought is to use a gs400/425 with the roller bearing crank ( stronger?) & then use 450 barrels/pistons to get close to 500 with maybe the same head.
are the barrels a straight fit from 450 to earlier motors & are later valves/heads ant better tham earlier ones, any info or sugestions would be gratefully received.
cheers herb.
will the barrel/piston of the 450 fit a 400?? what about the head?

[kidsixteen]

those cranks have a longer stroke, the 450 bottom end works but it's the same crank.

the 400/425 bottom end doesn't bolt right up to a gs500 either.

lots of ppl do bored 400/425's and get ~500cc bikes w/ roller bearings and kick starters... that's pretty cool imo. I've been keeping my eyes open for a barn find 425 for a while now.

[Kijona]

those cranks have a longer stroke, the 450 bottom end works but it's the same crank.

the 400/425 bottom end doesn't bolt right up to a gs500 either.

lots of ppl do bored 400/425's and get ~500cc bikes w/ roller bearings and kick starters... that's pretty cool imo. I've been keeping my eyes open for a barn find 425 for a while now.

While roller bearings are more reliable, plain bearings are far more simple and easy to fix. Even the new Honda VFR12 and 800's use plain bearings. 

But yeah, I guess if you never have to replace the connecting rods...you'll be okay.