I have a couple of spare cylinder heads that look like they have been oil starved and its scored the cam bearings and cam shafts, I'm guessing this must be a common issue? has anyone had the head line bored to use bearing shells instead of running direct on the casting? Howw can I prevent this happening to the good head I have left its out of a 43f

Never heard of shells being fitted, but have heard of salvaging the head by lapping and honing .

Hi
just make sure to oil it properly when assembling, and do the oil filling procedure right for first startup. The oil pump does not pump air, so the bike has to sit straight (not on sidestand) when filling oil. It is safer to even tip it a bit to the right really, as the oil channel to the oil pump is horizontal and you want any air bubble to be able to go away upwards. Let it sit a few minutes for the air to escape through the oil line into the oil tank.

Andy

Hi.
Some minor scores in the head alu Cam bearings, doesnt do any harm as long as you remove all scuffmarks protruding the surface. The cam itself you should replace. The Cam rotates in an thin oilfilm so it will work fine with som minor scores.


Kindly regards Brage

Hi, yes l have seen pics of this done. During my research for my 1VJ rebuild [I've done heaps] l came across this but for the life of me l can't remember where. From memory it didn't leave much meat behind the bearing shells, but l guess it has been done. I managed to find decent head and cam to replace mine though. cheers Spike

Everything is possible, and eventually you'll find someone who can do it.
My experience of this level of engineering is that unless you have a good friend who can do it, or be technical enough to do it yourself the costs become prohibitive and you're much better off finding a replacement.
I have a couple of heads that one day I'll get around to attempting to fix. If it goes wrong, nothing ventured nothing gained. I'd been told the following.
Lap the two jointing faces and then you can actually ream the damage out with an adjustable reamer to the size required by the new cam bearings. He didn't elaborate on clearance, but they give a tolerance in the Yamaha service manual.