Compression Test Results Question

[TombigbeeMan]

Hello all, I have a 1989 Evinrude 110 V4 mounted on a Stratos Fish & Ski that is rated for a 115 max. This engine runs like a champ when i'm by myself and there isn't much load. However, it is a little sluggish out the hole. When my wife and daughter ride with me I have to have someone move to the front of the boat to get it to plane out then it runs great once on plane.
My mechanical background is mostly just parts changing with vehicles and have changed rocker box gaskets on a Harley a couple of times. I have never worked on a 2 stroke engine let alone an outboard motor. I have changed the VRO to a mechanical fuel pump last fall due to the VRO (already disconnected) was leaking. Changed all the fuel lines and filters and spark plugs and new water pump.
Now to the compression test.....I just checked my compression on each cylinder and I have 117, 118, 120, and 75 on the lower cylinder on the driver side. Bingo! That should be my problem! I just ordered a manual and it's on the way. Question???? What would be involved in tearing down the head? Price wise if I get someone else to do it??? I'm alittle scared to tear into it myself, I could change the head gaskets myself if there isn't too many loose parts but if it needs rings or has a scratched cylinder wall then I would need to take it somewhere....Open to any thoughts and comments!!!

 

[HighTrim]

Re: Compression Test Results Question

Try a heavy decarb first. Sometimes you get lucky and it will free up the rings.

If that does not work, and before you get worried, pull the bypass covers and inspect the rings. They should "bounce" when you press on them with a small screwdriver. If they are stuck in the grooves, they are either broken or carboned up and frozen. Also a good time to inspect the pistons.

Then pull the head so you can inspect the cylinder walls. Let us know what you find. If they are scored/damaged they may need honing/oversizing. If the head looks uneven put emory cloth on a piece of glass and run the head in a figure 8 pattern to smooth it out. Install new head gasket, and torque to spec in proper sequence. Hopefully the old gasket was torn on the bottom.

 

[TombigbeeMan]

Re: Compression Test Results Question

I'm not turning a bolt till I get the book in, but exactly what "bypass cover" are you talking about, is this the plate on the side of the cylinder block?

 

[Daviet]

Re: Compression Test Results Question

Maybe this will help, item #20.
http://www.ishopmarine.com/ishop/js...CatFilter=BRP&eCatSupFldr=supplier-100-005-EJ

 

[TombigbeeMan]

Re: Compression Test Results Question

Thanks, will be starting with the decarbing procedure and hopefully my manual will be in by the first of the week. I will probably go ahead and order all the head gaskets and side plate gaskets also and replace them and inspect all I can. Looking at the head and cylinder diagram looks kinda strait forward but will wait on the book.....Thanks guys!

 

[TombigbeeMan]

Re: Compression Test Results Question

I couldn't stand it, pulled the inspection plate of the side of the cylinder...bottom ring was good, top ring not found! My thoughts is it may be floating around the top of the piston and screwing everything....Going to be pulling the head and inspecting tonight, even though I don't have the book yet, can't get no worse...

 

[boobie]

Re: Compression Test Results Question

Let us know what you find.