SeaDooMan, have you gotten any info on the lift of the stock or XR cam?

I have been thinking about doing this to my bike, trying to get as much info as I can before I make the swap.

Leo

 

ANOTHER UPDATE ON THE CAM MYSTERY

Ok, for an EX cam: duration, in & exh. 225 deg.
: lobe height intake 1.2076 in
exhaust 1.1995 in
for an XR cam: duration in. 232.5 exh. 232 deg.
: lobe height intake 1.2175
exhaust 1.2137
So, the question is answered, the xr cam does have a higher lift and longer duration. However, I believe that modifications can be made to the rocker box that can achieve the same lift and duration as the cam. Give me some time to do some dyno tests to prove this.

Here is some more info about the XR and EX valve train

XR intake opens at 11deg BTDC
closes at 41.5 deg ABDC
exhaust opens 40 deg BBDC
closes 10 deg ATDC
EX intake opens at 5 deg BTDC
closes at 40 deg ABDC
exhaust opens at40 deg BBDC
closes at 5 deg ATDC

Someone asked me about the thickness of the XR vesus EX head gasket. I will have to research that, if you have done a big bore, you don't need any more compression.

 

The XR head gasket will bump up compression by about .2 of a point...

Stock EX Compression 9.1:1
Stock XR Compression 9.3:1

One thing to keep in mind though, is that timing chains stretch with use, the XR head gasket effectively makes the chain longer which will in turn retard cam timing and add slop to the system.

 

ten point eight to one and no race gas< just premium>

 

So are you saying to not use the xr gasket? Is it worth it?

 

I'm saying it's not worth it for the compression gained, especially if you are already going to run a high compression piston.