head replacement in frame woes

The bottom end of the pushrods can't really go anywhere except in the cups of the valve lifters. The top ends you have to use a screwdriver or bit of stout wire to get them in position. You can't do that with the head fully down though as at least one of the valves wants to be open. I put something in the gap between the head and barrel enough to hold the head up a half inch or so, then get the top of pushrods seated. Some people use rubber bands on rocker arm to keep tension on pushrod. then remove spacers & use front centre bolt to pull head down. Rotate engine to make sure all pushrods are still ok then fit remaining head fasteners.

I had a miserable time with an RGM eyeletted gasket recently. Fitted it ok but after a 20 mile run it had compressed so much that all the head fasteners were only finger tight. Have now replaced it with an Andover one. Have told RGM about it via email but no response from them.

The bottom can go wrong! But not easily.  Just joggle about a bit and they should be OK.   I use a long piece of wire with a right angle bend on the end to hook the tops in place.  And lift the valve end of each rocker to hold the ball end down for each one in turn as soon as they are in the correct place.

I put the head back on mine only last month. The first time I’ve ever done it and struggled until I got a few tips to help me. This was how I did it:

1) Lower the engine by removing the main isolastic engine bolt and gently push the engine down by about an inch. Best to have a jack underneath to support it once lowered and then raise it back up when finished. Very simple to do and gives much needed room for the head replacement. 

2) Set the pistons pretty much to TDC. Get a “head torch” so you free up both hands and can easily see the pushrods in the head. Drop the head over the cylinder with the push rods falling down onto the lifters. You can then juggle them into place in the rockers with a screwdriver or similar with the head loose. You will find 3 go in easily and one will be too low and keep falling out of the rocker. That’s exactly as you want it.

3) Get the head bolts 3 and 6 in place just nipped up enough so they are secure. You might also use the front centre bolt as well. The valve springs supported by the 3 pushrods will keep the head tensioned away from the cylinder and the head gasket. Now tighten the two bolts by equal amounts very slowly until you can get the final pushrod engaged in the rocker. Make sure the other pushrods remain in place as you do so and continue to tighten the head down very slowly and evenly with the two bolts. At no point will the head touch the gasket before all 4 are secure. Add the other bolts and torque down in the correct order.

Worked for me! 

hello,

i havent got a commando, are the push rods of different lengths

Barry

Yes, the inner ones go to the inlet and they are longer. I think you would soon know if you got that the wrong way round but always worth asking.

Changing the head gasket on a Commando, in the street, by torch light, was always something of a right of passage. I remember a Mark Williams "Running Out Of Road" column going off on some Zen-like ramble involving Commando head gaskets and 'Bad Day at Black Rock'.

Anyway, I have a K100 I that I have the same sort of feelings towards so, if that's more your kind of thing, perhaps we could come to some arrangement.