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90hp v4 Compression question

S

sooley

New member
"Hi Guys, anyone know what the

"Hi Guys, anyone know what the compression of a 90hp V4 Seahorse (J90TLCNB) should be. and would anyone have a service manual or know where i can purchase one. My motor runs idols (somewhat), accelerates, but is rough idoling...even with new plugs and a clean carb...

any thoughts?"
 
"See top of page, 2nd icon &#4

"See top of page, 2nd icon (manual). Compression should be approximately 100+ psi and even on all cylinders.

With the plugs removed, the spark should jump a 7/16" gap with a strong blue lightning like flame.... a real SNAP! Dies it?

That 1982 90hp Johnson should be using Champion QL77JC4 plugs gapped at either .040 or .030 (try both settings)."
 
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