Hitchcocks Forum

Hi Everyone
I've got a 1974 350 bullet that's developed an oil lleak on the head. Its in front of the plug ,between the cooling fins. Any ideas or new head?
TIA
Mark

So long as it's not losing compression and you don't mind cleaning the oil off from time to time, I'd leave it be.

"..in front of the plug..." is pretty vague.. depends on where you are standing and viewing from. A picture would speak a thousand words, but is it completely separate from the plug or in connection with the hole the plug screws in to..? I have blackening around the plug.. which is normal enough for me not to worry about and looks like this:

Exile: If your bike is a 500, I would be very concerned about oil around the spark-plug...

Not really Tim.. he runs perfectly well. I never put the plug in with a heavy hand. I expect a little discolouration around the base of the plug. My Honda )from way back when) did the same.. So does my chum's Norton...

Hi Mdsparky I had similar problem on my 500 it turned out to be a porous spot between the fins on the same level as the plug and when riding blew back around the plug. Cured it by thoroughly degreasing the area, then filling the gap between the fins with high temperature silicone, 1000 miles and still be ok. See the pic hardly visible.

Exile, I too use a light touch screwing the plug in but it really depends on how many goes the compression washer has had. We used to be able to get replacement compression washers but nowadays we have to replace the entire plug. If the plug is loose enough to weep, Murphy's Law says it can eject, which will then need a plug insert done (it's not a Helicoil as such).



Clean the area scrupulously (vacuum it out, brush and rag), screw the plug in 'by hand' and then nip it up to the correct torque or turn as given by that plug manufacturer. As you say, it should not be with a heavy hand - but that blackening is far from normal.

Thanks Steve T, i'll try that as i think that's what the problem is
Mark

@jefrs..

OK. I degreased the area and had a peek at it. Nothing to see. I've nipped up the plug, so now it's a case of wait and see....

I still, flat out, refuse to worry about it...