Compression check

[Newbie@boats]

I did my compression check and got

C#1 135
C#2 135
C#3 130
C#4 130

Motor runs fine, but at WOT does 30mph and takes a long time to get there....What could cause this or thats all I am going to get out of my 125HP?

 

[kend301]

Re: Compression check

Comp looks ok .. You need to post a little more about your boat as in model and length. Also have you checked the carbs to be sure at WOT the butterflies are completely horizontal and not going past ? If they are it is like running at 3/4 throttle.

 

[pnwboat]

Re: Compression check

Compression looks good. May not be the engine at all. Need to know what RPM the motor is turning and what pitch prop you have. This will help in determining whether or not you have an engine problem, or a miss-matched prop. Too much pitch on the prop will put too much of a load on the motor causing poor performance.

If you don't have a tach and there are no markings on the prop, you could do a couple of ignition system checks. I'm assuming you have a late 1980's 125HP motor with the blue CD modules and coils?

 

[jerryjerry05]

Re: Compression check

Are the plugs all burning the same?Check the pump diaphram.
Check the reeds.
Ethanol has ruined a lot of older gas lines.Go thru and check for soft hoses.
Replace them if in doubt.
Do what the others recommend.Post the results.Performance depends on load,prop,RPM.J

 

[Newbie@boats]

Re: Compression check

Its a 19FT Bayliner capri cuddy cabin.

It does have blue coils.

It could be the prop....he did tell me that he replaced it actually. I will check on the prop for numbers.

At WOT the butterfly vavles are like this --------------- straight.

The pitch on the prop could be to great?

Maybe they increased pitch to try and get more out of it but decreased it by doing that?


I checked all fuel lines and they all look good.

The motor is a 1989.

 

[thompy]

Re: Compression check

souds like a tall prop how any rpms is it turning

 

[pnwboat]

Re: Compression check

It's a common mistake to increase prop pitch to try and get more speed. People don't realize that you also need the horsepower to be able to turn the prop at the required RPM's to get the increased speed. If you don't have the horsepower, increasing the pitch will have the opposite affect. It will decrease holeshot performance and top speed. Not saying that this is your problem, but without knowing what RPM and what pitch prop, you're just taking a shot in the dark trying figure out if you've got an engine problem, or too much prop.

 

[Newbie@boats]

Re: Compression check

Is there anyway I can hook a TACH up just to read what my motor is running?

I dont really want to buy and install one.

I will try to find prop numbers tonight.

I hope its just the prop.

 

[ezmobee]

Re: Compression check

A tach is perhaps the most useful instrument in a boat. I would recommend purchasing one. Outboards need to be propped correctly in order to make sure they are able to hit their target WOT RPM range. If they can't, you may damage the engine. You will need a tach that will work for a Force motor. www.greatlakesskipper.com had a ton of Force tachs for very good prices last I checked.

 

[Newbie@boats]

Re: Compression check

I looked for any numbers on my prop and cannot find anything....now what?

 

[jerryjerry05]

Re: Compression check

If it's original it's stamped on the side.Either a 17 or 19.
Like they said without a tach it's gonna be impossible to figure it out.J

 

[kend301]

Re: Compression check

Since it is looking like the issue is going to be prop or trim area , I only know jet drives and will bow out of this thread .. Good Luck !!

 

[jasonbailey]

Re: Compression check

Have you check the hull flotation foam for saturation? Before you get too wrapped around installing a tach, check to make sure everything is nice and dry on the inside. You maybe hauling a bunch of water weight.

Being a 1989 model, I would look there first.

 

[Newbie@boats]

Re: Compression check

How would I check the foam?

 

[ezmobee]

Re: Compression check

The easiest way is to cut a hole in the floor and take a section of PVC pipe with some teeth cut into the end of it and jam it down into the hole through all the foam till you hit the hull. Then examine the plug you pull back out to see if the foam is wet. Wet foam can add hundreds of pounds to your boat.

 

[chillin014]

Re: Compression check

I'm curious what your process was for checking the compression. I checked mine and it checked out at factory spec. I later read that you are supposed to achieve the specified compression within very few turns of the motor. It was taking me a bit of cranking.

Regardless, my boat is slow because of the wet foam most likely.

 

[Newbie@boats]

Re: Compression check

I cranked my motor for about 3seconds max of turning the key.

It all check out great.

Im going to check the foam.

Now...lets say the foam is wet...how would I dry it out?

 

[wan2live]

Re: Compression check

I cranked my motor for about 3seconds max of turning the key.

It all check out great.

Im going to check the foam.

Now...lets say the foam is wet...how would I dry it out?

I took the wood off of the foa that was wet in my boat and let it air out, I used a shop vac to get alot out but if you have water deep into the foam that is not going to work to well, I had maybe 3 inches of foam to dry out.

 

[ezmobee]

Re: Compression check

Unfortunately it will never dry out. I mean NEVER. The only option is removal.

 

[Newbie@boats]

Re: Compression check

I think my drain plug was clogged up a little bit, I open up the middle storage thing in the floor and it was full of water.

I cranked the boat all the way up it the front and it wouldnt pour out....

I stuck the top half of a fishing pole into the hole and water slowly started coming out, along with leaves, rocks and other garbage.

Then finally a burst of water came out, think I got it cleared up, I still have the boat high in the front to drain any water. Uncovered it and left the cover off in the floor, hopefully it will continue to drian, and slowly dry up.