fitting the XL600 barrel to my GB500

[danny baker]

I've got my XL600 barrel and piston and have decided to go for it.
There are a couple of things I'm not sure about.
For a start the GB has a oblong hole in the barrel between the sleeve and the cam chain and the
XL doesn't. I believe it is for draining water which may build up in the spark plug hole. Do I drill a
hole in the XL barrel ?
The other thing.....what head gasket should I use. If I use the GB one then it will protrude into
the barrel. Can this be fitted like this or can I trim the gasket.
Has anyone out there done this mod.

[guest27]

I do no tknow the detail for the GB etc, but the head gasket should not protude into the combustian chamber - causes lots of different problems.  Some one will know the definitive answer to thins one - but I would be looking at the 600 HG and possibly blending the land on the head into the squish - if there is one.

R

[danny baker]

I will answer one of my own questions....the drain hole cannot be put into the XL barrel because
the sleeve is bigger and there is not enough room.
Back to the head gasket.....what happens if you bore out the GB sleeve to it's max you would
still use the standard GB head gasket ??

[guest27]

The head gasket should - as I understand it - match the bore - usually there is only a mm or 2 for reboring - so the HG will be pretty close - and I would guess could be made closer - but when you make bigger changes the gasket sits into the combustion chamber and gets heated, distorts, shields the charge etc. The biggest of which is probably the over heating of the portion in the chamber.

R

[Richard 003]

The head gasket should - as I understand it - match the bore - usually there is only a mm or 2 for reboring - so the HG will be pretty close - and I would guess could be made closer - but when you make bigger changes the gasket sits into the combustion chamber and gets heated, distorts, shields the charge etc. The biggest of which is probably the over heating of the portion in the chamber.

R

You need to be on the Thumper Page, talking to people like Randal Zempel and Rob green, if they're still about.

[Richard 003]

The head gasket should - as I understand it - match the bore - usually there is only a mm or 2 for reboring - so the HG will be pretty close - and I would guess could be made closer - but when you make bigger changes the gasket sits into the combustion chamber and gets heated, distorts, shields the charge etc. The biggest of which is probably the over heating of the portion in the chamber.

R

You need to be on the Thumper Page, talking to people like Randal Zempel and Rob green, if they're still about.

Ps is that the GB engine I sold you in 1997, or have I got you confused with someone else? ;-)

[danny baker]

Looks like Randal Zempel email is not operational anymore.

[danny baker]

Update so far...
the XL barrel is on using the XL base gasket.
I'm going to use the GB500 head gasket which I have modified by opening up the diameter to
match the XL barrel.
Valves reground and now waiting for new oil seals before I can fit.
My GB500 cam is a little worn but I have a very good XBR500 cam.
The GB cam has the marking R1
The XBR cam has the marking R3
does anyone know the difference.
I have measured the cam height and it seems the GB has a slightly higher lift.
I/m not sure which one to use.