XBR500/600/650 barrel dimensions etc

[guest18]

Ok one for the experts,
I have possibly got the option of a barrel and piston believed to have been fitted to an XBR based motor which is thought to be either 600 or 650cc

So, does anyone know off the top of their heads what the dimensions are of the likely donors, if 600/650 barrels will bolt straight into a 500 bottom end (and head)

Tough one I know(!)
GC you will know the gentleman in question as he sold you a SLR650 engine that needed the exhaust studs doing  (and beat me to it lol)

[guest7]

If you go to www.thumperpage.com and look for the GB FAQ article, I'm sure there's a good spec list there that will help.

[guest146]

Can tell you the 650 has a bore and stroke of 100 x 82mm and the 500 has one of 92 x 75mm.

Ken

[guest7]

I never thought I'd be contributing techie anorak details, but apparently across the RFVC range the stroke is changed via the piston pin to crown height, the bore length is the same across the range... or so I've been told.

Er... can that work, isn't the length the piston travels the same anyway, just starting from a different height?

Cheers
GC

[guest295]

The GB and XBR use a sleeved XL600 engine, apparently. I think there may be slight variations in the GB400 crank, but I'm not sure. The bore can apparently go out to almost 100mm before problems set in. They say the starter fails if the compression goes up much.

[guest146]

I guess if they use the same barrel and fit it to several engines by fitting pistons with the gudgon pin in diferent places you can do it. By doing that you can bring the piston up the the required place, it just means you have an unused part of the bore at the bottom on some engines

Ken