Engine 7 - Cylinder Head

The better of the two cylinder heads had cleaned up nicely, but I needed to check over the conditions of the valves and guides etc. The valve spring remover I had was only just fit for the job really and there were various points where I was expecting everything to go belly up with springs flying all around the workshop, never to be seen again!! Eventually, I got everything safely stripped down.

The carburettor that I am using (again, better of two that came with the bike) is from a later bike with a bigger bore, whereas the cylinder head inlet is designed for the smaller bore. So I did a little tuning / porting work with my Dremel and a small grinding stone to match the inlet to the carb, using the carb gasket as a guide to how much metal I needed to remove. The pictures below show the steps.

The head itself cleaned up nicely after lots of hard work stripping off a curious pink residue. I also lapped in the top surface, using fine emery paper and oil on a flat sheet of heavy MDF)  to get a nice flat gasket joint with the valve cover.

The valves themselves seemed in reasonable condition and there wasn't any great play in the guides, so I have left those. However, everything needed a good decoking and the valves were definitely in need of grinding/lapping into their respective seats.

So out with the old sucker on a stick and valve grinding paste!

Some time later, things were looking much better!

Another perilous half hour with the barely usable spring compressor saw the valves and springs reinstalled. A short while later, I realised that I had put some of the springs in upside down so it all got repeated to correct things!

With the head steady refurbished, I annealed the copper cylinder head gasket and fitted the head. Important to note is that there are special washers that should be used under the cylinder head bolts to stop them damaging the head casting and allow you to torque things down properly.

 

The rocker gear got a quick strip down and clean up - all seemed fine other than I dressed the ends of each rocker just to smooth them off a bit and hopefully stop a bit of future wear. 

I had to replace the end of one of the pushrods which had a peculiarly wrong fitting on it. Who knows what had gone on there? But, with that done, the pushrods and rockers were installed and the clearances set. Unusual ground for me this, as every other bike I've worked on has been an overhead cam, so not had pushrods.

I also installed the rocker oil feed lines, with new copper sealing washers. Turning the engine over using the kickstart, we had compression!