Compression

onebadc10

Seaman
Joined
Jan 22, 2005
Messages
55
Is this compression on #3 something to be concerned about.It is a 1999 90hp two stroke
cyl 1 140psi
cyl 2 130psi
cyl 3 140psi
cyl 4 140psi
 

keiken

Cadet
Joined
May 19, 2011
Messages
9
Re: Compression

If your talking about the 10psi difference then no thats perfectly reasonable. You want all your cylinders to be within 10-15% of eachother (depending who you ask).
 
Joined
Oct 28, 2010
Messages
923
Re: Compression

That is in the range of a good condition engine but I would run some engine tuner (I prefer OMC brand) let it sit overnight and then give it a good run and then recheck.
 

1nebel0

Chief Petty Officer
Joined
Nov 28, 2005
Messages
512
Re: Compression

Sea Foam works better but you will smoke out the neighbor hood...I had a v6 Merc that had compression all over the board and after using a cocktail of 1 gallon of gas and one 16oz can(fuel injected motor) compresson raised on all and even them out to within 5 lbs of each other. I sea foam my engines once a year....Merc makes a product as does OMC above....Sea Foam is used by a number of my buddies in their shops to get cars to pass as it will reduce emissions as it is cleaning up carbon out of the valves....DONT DO THIS IN FRONT OF YOUR GARAGE WITH THE DOORS DOWN..THE SOOT WILL STAIN THE DOORS!!!!!!
 

Faztbullet

Supreme Mariner
Joined
Mar 2, 2008
Messages
15,931
Re: Compression

I myself do not recomend the seafaom as I have seen several motors fail after treatment. I use Merc's Powertune or OMC Engine tune-up along with Quickleen or CarbX as afuel additive. Are you sure its a 90 hp 2 stroke as Merc on makes a 4 cylinder 90 in a 4 stroke.
 
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