Cylinder gasket 1 or 2???

Leighton

Member
Joined
Nov 9, 2019
Messages
49
My head gasket has started leaking/blowing.

I have got a replacement gasket set already...
The gasket that goes between the crankcase and cylinder moulding has 2 gaskets.

Is there a reason for this, should I replace with 2 or can I use just 1?

Thanks.
 


Leighton

Member
Joined
Nov 9, 2019
Messages
49
Hi, just getting round to fixing this. It was always leaking a bit where the 2crank housing Half's go together and where those meet the cylinder, just under the exhaust outlet. Having it all now apart it appears the crankcase doesn't quite sit level.
I have no way of planning it all level.
I was thinking of soaking the cylinder gasket in oil overnight before I put it on, so hopefully it'll expand and fill the gap better? Would this work?

Should I replace with 2 gaskets or one?
Do you think that extra one will make it worse or better seal?
 

Chainlube

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Joined
Jan 5, 2020
Messages
1,951
The best way to tell is put one on, and rotate the engine to TDC and see if the piston comes up past the cylinder bore. If it's even or slightly below you're good, but if it's the thickness of the second gasket below the top, then use the second gasket. As far as sealing goes, if it's torqued down correctly it will seal.
If you have an uneven spot on the case you can file it down by using a good sharp file laid flat across the case. Got a picture of the uneven area?
 

Leighton

Member
Joined
Nov 9, 2019
Messages
49
Hi thanks for your input.

I have put 2 gaskets. These were the brown paper type. Replaced the head gasket too and put it all back together. It's not leaking around the head gasket front anymore, I did sand the head down a touch though, it was slightly out of shape... The bottom crank bit is still leaking a bit tho.
It's right at the front where the two pieces come together, because it's not dead flat the cylinder gasket isn't mating right.
 

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Medic

New Member
Joined
Jan 31, 2020
Messages
13
Two gaskets were probably put on by the factory builder to adjust the timing.

If your getting full exhaust and your intake clears the port you can run 1 gasket but I would guess there are 2 for a reason.
Reason would be to raise the jug and adjust the timing.

The triple 40 I bought from Amazon came with 2 base gaskets also.
 

Akutey

Well-Known Member
Joined
Dec 10, 2018
Messages
417
Any changes to the gasket thickness alters timings of all the ports.

Blindly adding in or removing gasket thickness can reduce performance or worse cause damage.

Most circumstances it slightly increases port duration but decrease's compression, ruin's any chance of squish band without filing which will again alters the timing.
 
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