1985 B&S 3.5HP Flathead - Head gasket change

[IPCOlsenVZ]

Family had the mower since new. Changed the head gasket only to have a sticky beak at the cylinder bore. Was the original gasket.

Oil usage: Need to top it up about 50ml every time I mow but it does have an oil leak at the output seal so its difficult to estimate how much leaks from there vs burns up past the rings.

Initially I don't think it got much maintenance but then I got older and I started looking after it about 15 years ago. Now runs on M1 15w50 with a touch of M1 Racing 2t in the fuel.

New gasket looks like this:

Has the extra 2 points in red just sitting out in the combustion chamber, not clamped down by the cylinder head. Seems wrong but the part numbers all match up with this engine.

Any advice if this new gasket is ok?
Does the bore look ok? I have a new set of standard size rings on hand, would changing them over be worth considering? I haven't done a compression test yet, that's next on the list.

 

[oil pan 4]

My number 1 backup mower is one of those, well that engine at least. The bore lookes great.
Just trim off the gasket that hangs out in the combustion chamber.
Does it burn any oil?

 

[wag123]

That head gasket looks like it is for a later model 3.5hp engine. Is it OEM?

 

[mk378]

Place the new gasket over the head; do the bolt holes in the gasket match?

Unless there is damage to the gasket, these engines can generally be taken apart and reassembled reusing the old head gasket.

It will be easier to work on if you take the top cover off.

 

[Lawnman23]

This would be the one you want:

Amazon.com

Looks to be a few different gasket shapes for that model. Lay the gasket you have on the head and see how it lines up. The tabs can be trimmed to fit if that's all that's in the way.

EDIT: I see you are in AU, will want to find that part number a bit more locally

 

[IPCOlsenVZ]

Thanks for the replies, when I get some time I'll follow your advice.