My kids Mini did not pass emissions about two years ago and his money was good so he bought a Toyota but never followed up and sold the Mini. There is sat in my yard where the mice bugs and mud dabbers had their way with it.
Two week ago he tells me how much he misses the car and want it back on the road.
Off came the head.
Having my own machine shop is very helpful. I replaced two valve in number 4 cylinder. For refence compression 1,2,& 3 where at 160psi. number 4 was at 60 psi. If you think of water cutting dirt going down a hill the flame cuts channels in the valve.

I am not really sure if the valve was closing but the good thing was the seat was undamaged. I did grind all the exhaust valves. Then a quick hone and re-installed with new valve seals. Note if you plan on doing this... use a deep well that goes all the way over the seals. Do not tap on the top of the seals.
Some tool you'll need something to hold the cam in place, a mount to hold the engine up after you pull the upper mount, and a piece of welding wire to pull the chain back up.
I'll add photos when I get them.
The only had part was getting the plug back on the alternator after installing the intake.

Hope this helps someone.

 

Thanks for sharing. Your son owes you a beer.

 

Make sure all your vacuum lines are good and not cracked either.....a vacuum leak will cause this also......

Bryan

 

Did you figure out why it burnt a valve?

 

Was this on a Cooper R50 or a Cooper S R53? I had this happen on my '06 R50 non-S, and I think that the exhaust valves on a non-S are not as hard wearing as the S valves. When Detroit Tuned did the work for me, they replaced the valves with the stronger S items.