Norton dominator

[Christhurlow61]

Can any norton dominator owners help .i have a 1959 dommy with a leaking cylinder head but not oil but fuel .i have now dismantled and replaced it 3 times .i have annealed a new copper gasket checked flatness of head on a plane of 6mm glass tightened all bolts and nuts in proper sequence and torqued to correct amount but still it leaks .now looking at stripping for a fourth time .is there any norton owners that can help please

[trickywoo]

What is leaking and where from exactly?

[Christhurlow61]

It’s fuel and it coming from where head meets the barrel at the rear under carb but definitely coming from head gasket

[trickywoo]

I’d suspect a crack in the head if you’ve exhausted all the other possibilities of how fuel is leaking.

[Krikkit]

Did you take it apart because it was leaking?

What do the surfaces look like while apart? Seems odd it would only leak fuel and not exhaust as well if it's the head gasket.

[Rubin215 QFSM]

Christhurlow61 said:

It’s fuel and it coming from where head meets the barrel at the rear under carb but definitely coming from head gasket

What signs are you seeing?
Can you post us a photo?

Straight away, I am a bit wary that you are seeing fuel from the head gasket; bearing in mind just how little fuel is actually drawn into the cylinder on the down-stroke I would be very surprised if you could see it leaking out.

I would start looking at the carb itself and see if there are any leaks or cracks that are allowing fuel to seep out.
Try dusting the whole thing with talcum powder and any leaks will soon be evident.

[srob]

Rubin215 QFSM said:

Christhurlow61 said:

It’s fuel and it coming from where head meets the barrel at the rear under carb but definitely coming from head gasket

What signs are you seeing?
Can you post us a photo?

Straight away, I am a bit wary that you are seeing fuel from the head gasket; bearing in mind just how little fuel is actually drawn into the cylinder on the down-stroke I would be very surprised if you could see it leaking out.

I would start looking at the carb itself and see if there are any leaks or cracks that are allowing fuel to seep out.
Try dusting the whole thing with talcum powder and any leaks will soon be evident.

I'd tend to agree.

Are you sure it isn't fuel leaking and either dripping on the engine or tracking down somewhere else and onto the head?

I once had the float stick on one of the Velocettes and fuel was spraying out of the overflow in a perfect jet and hitting the back of the spark plug. Which was a bit scary

[Krikkit]

srob said:

I once had the float stick on one of the Velocettes and fuel was spraying out of the overflow in a perfect jet and hitting the back of the spark plug. Which was a bit scary

crikey

[srob]

Krikkit said:

srob said:

I once had the float stick on one of the Velocettes and fuel was spraying out of the overflow in a perfect jet and hitting the back of the spark plug. Which was a bit scary

crikey

Yeah it was one of those! It just started bogging down like it was flooding, so I looked down and saw a perfect jet of fuel spraying from the carb' to the plug lead. It's an old 1920s racing bike so doesn't have a plug suppressor cap on either just a bare wire onto the top of the plug. Luckily as it's an old racing bike it also doesn't tick over so I pulled the clutch in and with no revs the engine died immediately.

I coasted to the side of the road with steam pouring off the cylinder and stuck it on the stand hoping it wasn't going to go up. Luckily it didn't - guess there was no source of ignition by then, but it was still scary

[Christhurlow61]

I can’t see anything wrong with barrel or head other than getting a magnifying glass and studying it .but it’s definitely fuel 100 % no oil carb does not flood .i was wondering if carb was putting to much in but regardless of that it should be sealed thought of using some sort of sealent .maybe a different carb .but don’t no what to do it’s driving me mad trying to stop it leaking I only want to put it back together one more time.

[GadgeS3C]

I'm in agreement with other here, it sounds like a carb leak ending up in an odd place.

Highly recommend using talcum powder to see if you can see where the petrol is coming from. Unless the float is sticking and fuel is flowing into the cylinder (and not pissing out the float as normal) I struggle to see it coming from the head joint. I vaguely recall hearing of a Commando (with inclined cylinders) having that happen but can't see it on a Domi.

Has it been leaking while running or just standing?

There will be a logical explanation - even though it's brit bike gremlins!

[Christhurlow61]

Fuel deffinatly making it into the head .there are no leaks form the carb .somhow it is making it past head gasket

[GadgeS3C]

Christhurlow61 said:

Fuel deffinatly making it into the head .there are no leaks form the carb .somhow it is making it past head gasket

Is the sump full of petrol?

[Christhurlow61]

Can’t give photos as it is striped down again

[Christhurlow61]

When I removed head copper gasket is wet on both sides with fuel

[Rubin215 QFSM]

When it was together did it run?

It strikes me that a head gasket leak bad enough for you to have fuel outside the cylinder would be very noticeable when it started.

Have you done a compression test?

Ultimately, you're going to have to put it together again anyway, so get that done first and then take it from there.

[Krikkit]

Christhurlow61 said:

When I removed head copper gasket is wet on both sides with fuel

Have you checked the surfaces for flatness?

Surprised it's a pure copper gasket, wouldn't have thought that would be soft enough.

[gareth_r]

Krikkit said:

Have you checked the surfaces for flatness?

Surprised it's a pure copper gasket, wouldn't have thought that would be soft enough.

It is, when it's annealed.

[crofty1984]

Could it be a leadky tank dripping on the head and the petrol finding its way to where you think it's leaking?

[Krikkit]

gareth_r said:

It is, when it's annealed.

Makes sense