91 yamaha 150 leak down test

[jhosea1979]

while doing a leak down on my 150 i could hear leakage coming out of the spark plug holes #1 would leak into #3 #3 into#5 #5 into #3 1,3,5 where around 35-55% does this mean its a leaking head gasket? if so would that cause a lost of 1000 rpms cly 2,4,6 were all around 12-20% with no leakage into the other cly any thoughts??

 

[99yam40]

Re: 91 yamaha 150 leak down test

If this is a 2 stroke, the most obvious way pressure will get to other cylindercombustion chambers would be head gasket.
If it was heading past piston and rings then it would have to get by the crankcase seals in between each crankcase also

 

[jhosea1979]

Re: 91 yamaha 150 leak down test

it is a two stroke would that cause such a lose in the rpms? what would cause a head gasket to just go bad it was running fine before?

 

[99yam40]

Re: 91 yamaha 150 leak down test

over heat and warped head, cracked head, or corrosion eating through head or block are my thoughts