Exhaust gasket melting

[Carlos motors]

And what do you think why is my exhaust gasket melting

 

[butre]

Jaguar is giving sound advice, but it's not pertinent to the problem. the mating surface between your exhaust pipe and your cylinder isn't flat. the easiest way to fix that is a belt sander, but a file will work in a pinch.

 

[Deleted member 12676]

if it's not due to blowby due to uneven mating surfaces then its because the exhaust gas temperature is too high

 

[Carlos motors]

Yes I think exhaust is too hot. Why is that? Spark plug? Compression? Fuel mixture (I put 20:1 (should mixture be with more or less oil in summer))?

 

[Deleted member 12676]

factors that increase exhaust heat:
incorrect jetting
too high compression
too advanced ignition timing
increased exhaust port height

take note that as you increase engine compression you need to retard ignition timing. that is because higher compression causes a faster burning of the fuel mixture and if the peak combustion pressure happens before 10 degrees ATDC then that increases peak combustion temperature

 

[butre]

advanced ignition timing does not cause your exhaust temperature to be too high. you know how cars that spit flames do it? they retard the hell out of the timing. advanced ignition timing does contribute to a higher running temperature, but not a higher exhaust temperature.

 

[Deleted member 12676]

You're right, it just causes excess temp/pressure in the cylinder near TDC which causes excess head temperature.
my bad

 

[Carlos motors]

And I asked you what about fuel mixture in the summer? I red that when fuel-air mixture is too rich mb when going downhill go slower and four strokes.
So I think that I need smaller yet or leaner gas-oil mixture or both

 

[Deleted member 12676]

summer requires the carb to be slightly leaner (smaller main jet) than in the winter

 

[Carlos motors]

And fuel mixture 25:1 full synthetic?
Also for the spark plug i have ngk br6hs but here temperatures go to almost 40C so I want colder one. Which do you suggest?
And do I need to buy new jets or I saw somwhere you need to drill it