750 head gasket

you will get many different answers to this one! personally i prefer the composite head gasket if i use a copper one i always anneal it before use new or used also a piece of dental floss around the pushrod tunnels is favoured by many,whats the history of your engine has it recently had a new head gasket ? it may need to be tightened down! also are you certain its the head gasket? regards nick

Nicholas is quite correct about personal choice. Most people have their favourites. 3 years ago I purchased solid coppers gaskets from RGM for a 750 Commando and Dommie 650. I annealed both before fitting. The commando gasket was fine to start with but then I got a small weep from the RHS which got worse as the miles mounted. The Dommie gasket p*****d oil out of the RHS as soon as I passed 4000rpm. A change of barrel and cylinder head made no difference despite another annealing.

Meanwhile the Commando was treated to a rebore and the solid copper gasket reused after another annealingsession. By now my wife was complaining bitterly about the brand new gas ring being mis-used but this was the only way I could get one half of the gasket cherry red while a gas torch took care of the other.

A tip, from another Commando owner, resulted in the purchase of a tube of High Temperature Silcone. This was lightly smeared across both faces of the head gasket and the rocker cover gaskets. The result has been no leaks at all from the head even after heavy throttle action.

Pesonally, I have always favoured the composite gaskets but in recent years have purchased several that disintegrated after low use. The drawback of the solid copper versions is the annealing process. If you don't do it correctly you end up with hard spots or burn away the gasket in the thin areas such as outer bolt holes.

Yes , definitley two or three schools of thought here. My own experience on a 750 and 850 Commando is the original composite type head gasket works best.

Admittedly never annealed the copper ones I tried althoughdid retorqueheaddown aftersome 2 or 300 miles as recommended. They still started weeping after quite a short mileage. Changing to the composite gasket cured the weeping more or less permanently.

I followed Norvil's advice and fitted solid copper gaskets to my Commando and Atlas.They must be annealed,and fitted within 30 minutes,using the thinnest possible smear of silcone.Re-torque the head after 100 miles,and again after 4 or 500 miles.Both engines show no signs of weeping,even after thrashing.Composite gaskets will eliminate leaks,and interestingly,Norvil used to use them as standard,but stopped using them for a while,as the manufacturers started making them with a harder metal flame ring,which wouldn't crush satisfactorily.I beleive they now come with a copper flame ring,but obviously can only be used once-i'll stick to solid copper,it's everlasting (in theory!)

Previously david_stromaine wrote:

I seem to have an oil leak from the front of my 1971/ 750 and have read so much about head gaskets am a tad confused. I would probably go for a quality copper one myself is that the way to go?

Hi David. As you say its worth wrapping up your tacho drive just to eliminate it,as i had the same problem of oil running out from the front fins after a run, after much re-tightning it turned out to be oil travelling up andblowing back from the cable. I have fitted the new type cable and drive and used plenty of silicone and ptfe tape but i still get some after a long run.

Mark.

By now my wife was complaining bitterly about the brand new gas ring being mis-used but this was the only way I could get one half of the gasket cherry red while a gas torch took care of the other.

You do not need to anneal all the gasket in one go, just as long as all the gasket gets to cherry red at sometime in the process the whole gasket will be annealled. So you can start at one side and move along in sections geting each section to cherry red. The plung into cold water is also optional, it helps get rid of some of the deposits but has no affect on the anneal which will be fully soft.

So for this purpose you can leave the gas ring alone and stick to the gas torch.

I thought that the points lead bypasses the timing cover oily area. ie chains. sprockets and pinions.

When I fitted a Pazon, 3 years ago, I did not bother with the grommet which had got a large elongated hole in its centre. Of course some time later, when I checked the timimg, I found water inside the points cover. Then I silconed around the lead to seal it in place. I have never seen a drop of oil near the lead exit point. Only out of my replacement rev counter drive cable nut!

You may find oil coming from the rocker spindle covers "appearing" to come from the head gasket. (The airflow, at speed, is strange in this area) A small blanking plate made to cover the revcounter drive whilst it is dissconnected is a temporary test. I buy my composite head gaskets from Andover Norton. Then you get what you should, not something else of dubious specification. You shouldn't have to rely on a sealant on a head gasket if it is fitted to clean flat sufaces. A copper gasket may be softened by annealing, but it will still not be particularly soft. The torqueing figures are not going to crush a copper gasket into shape when spread over the area of a norton twin head IMHO