A10 oil leak

[RGS man]

Hi Guys, Now got my RGS back on the road, looks great, starts and runs well. However, there is an oil leak from the cylinder head where the right hand exhaust pipe goes into the head, the oil is leaking from some where, it doesnt seem to be from the rockerbox, it seems to be coming out of the exhaust hole and running along the fins and down onto the magneto. I have no idea, anybody got any ideas?   Regards   RGS man (Mark)

[RichardL]

If you are using a solid copper head gasket, did you anneal it to dead soft before assembly. When they come from the distributors they are still somewhat hard. It could be that oil returning from the front rockerbox chamber is being blown past the gasket as it drains toward the crankcase. The point about annealing is really a necessity, I've been tought here and have experienced the results of failing to do it. The rest is just one possibility, and a guess at that.

Richard L.

[A10Boy]

And If you are using a composite head gasket, run the engine through two or three heat cycles, then re-torque the head bolts.

When annealing a solid copper one, it really needs to glow cherry red. Its not an easy thing to do. If you don't have gas kit, hot coals on a BBQ work well but you will need to watch it closely and pull it out as soon as its red hot.

[BSA_54A10]

hot coals on a BBQ work well but you will need to watch it closely and pull it out as soon as its red hot.

Be a little careful with this one
Copper adsorbs carbon and becomes hard & brittle.
So if you have a gas powered BBQ with a layer of scorpia ( oft called "volcanic rock" ) then that is fine but if you are using charcoal then it is not a good idea

[RGS man]

Hi Fellas,
Thanks for the input, I did anneal the gasket (I presumed it was ok) maybe I should take another look at it. A couple of people said it could be oil control rings, which of course will mean rebore etc, etc, I wonder if I should also look at that. The bike is smoking, but not excessively, I didnt do it initially, I thought the pistons etc were good. I am not too worried about the cost, I should have done it in the first place methinks!!

Cheers  Mark (RGS man)

[muskrat]

An old bloke once said to me " let it develop ". Give it another 100 miles. Sounds like a valve guide. Either loose or worn letting oil into the port. An alloy head RGS should have bronze guides. If one is loose I saw some 0.002" oversize on fleabay yesterday.
Cheers

[a101960]

I agree with Muskrat. Ally heads are well known for loose valve guides. The guide will most likely appear to be firmly in place when the head is cold, but do not be deceived. I had a loose inlet guide and oil was getting past. At first I thought that the tappets needed adjusting. The engine was quite enough when cold but once it was warmed up there was a 'tappety' rattle. See the picture you can clearly see the burnt oil deposits on the timing side piston. New guides cured the problem completely.


John

[BSA_54A10]

To check if the head gasket is full soft, roll your thumb over on it.
You should be able to indent it with your thumb nail and make a clear crescent dent if it is full soft.

[RGS man]

Thanks Guys,
When I had the head done up, I had new Guides put in, maybe one is loose. I think that sounds to be the best starting point.

Cheers  mark (RGS man)