Low compression on one cylinder.

[hawkster]

Is it possible that a reed valve be stuck shut ( or not functioning properly) to not allow maximum air/gas mixture into the cylinder to build full compression? My Mothers boat has a 1990 Force that ran perfect until she hit a rouge wave that literally slammed her boat to a dead stop. After this it didn't have the power it used to so she took it to a boat shop to have it checked. They told her it had low compression on one cylinder and they felt it was the reed valve due to the wave incident and the fact that it still ran just not as good. Thanks for your input.

 

[jerryjerry05]

Re: Low compression on one cylinder.

Need to know the compression results.What hp.Profile?
Don't know how a wave will affect the compression.A wave might break something loose in the tank and allow garbage up into the pump/carb but not compression.
Get someone different to do a comp/spark test.Check all connections, a lead might have come loose.J

 

[JB]

Re: Low compression on one cylinder.

Reed valve causing low compression??? Hogwash. Maybe if the reed shattered and pieces got into the cylinder.

A hard shock could very easily knock something out of place, screw up the link 'n' synch or control cables.

Get a second opinion from someone who doesn't have an axe to grind.

There are some who give us liars a bad name.

 

[Frank Acampora]

Re: Low compression on one cylinder.

Since on a 2 cycle engine both the exhaust ports and bypass ports are open at the same time, Cylinder pressure goes to atmospheric. Thus, the compression ratio of any cylinder is independent of the reed valves or throttle position.

Buy yourself a compression tester for around 30 bucks or so and do it yourself. Good results are all cylinders above 120 and within 10% of each other. Then come back with the results.

Take off the carbs and look into the manifolds: A broken reed while independant of compression ratio will affect power. Check the carbs themselves for dirt and/or clogging.

Check each cylinder for spark. While unlikely, a good hit could have jarred loose an electrical connection.