Force 50 running on 1 cylinder?

[blueoval78]

Hello everyone, in my never-ending quest to determine if my Force 50 is running correctly I have thought of another potential problem for my seeming lack of power. My motor starts fine, idles fine, accelerates to a top RPM of 4500; albeit slowly. I have to get the second person in the boat to sit in the bow to get it to plane.

I was speaking to a person who has an '87 Force 50 for sale today and he said his motor is running mint and pushes his Capri 1500 to 37mph. Mine will only go 25mph.

My question is, what are the symptoms of running on only 1 cylinder? I've had the carb and fuel pump rebuilt and put 2 new spark plugs in it but my motor really seems to be lacking punch.

Would running on 1 cylinder allow me to do 25mph and have difficulty planing?

 

[Cannondale]

Re: Force 50 running on 1 cylinder?

Have you pulled the plugs after running it and looked at them? A non-firing plug will be quite obvious.....wet, fouled looking, and appear to never have fired, which should be the opposite of how the plug in the firing cylinder looks.

Easy way to determine if you've really got a non-firing cylinder.

 

[jerryjerry05]

Re: Force 50 running on 1 cylinder?

Basics. Compression,spark and fuel.Running on 1 cylinder would definatly do that.You can have good compression but still have a bad head gasket.
Compression should be even or close.Spark should jump 7/16 in.
Do a comp test.What do the plugs look like after a run?Do a spark test.
Make sure the fuel system is clean and no crap in the lines.
Post your results.J

 

[dwe]

Re: Force 50 running on 1 cylinder?

You didn't mention what year Force you have??
First of all, if I were you, I'd get proof from this person selling the '87 Force 50 or water test it yourself because I am very skeptical (unless I have the same problem you have). I'd possibly believe it if it was a 70 Hp.

I have a 1990 Force 50 and I have never gone over 28 mph. I've had the compression tested and both cylinders have good compression and I've got new spark plugs and fresh gas and decent prop (I believe 10 7/8 pitch).

You've tried different props?

What's the altitude where you're boating?

 

[blueoval78]

Re: Force 50 running on 1 cylinder?

My motor is a 1988. I have a 13.5 pitch prop. I am @ 4500 rpms @ 28mph by myself in the boat. If I bring a passenger, I drop to 4200 rpms and 25mph. I tried a 11.5 pitch prop and dropped to 25mph by myself and 24mph with a passenger. The fuel pump and carb were rebuilt in June with 2 new plugs. One clue though, the previous owner smoked some rocks last year and had to replace the whole bottom end. Could the timing have been thrown off?

 

[emoney]

Re: Force 50 running on 1 cylinder?

What size boat is it on? How much does it weigh?
Sometimes, it could just be inherrent in your complete rig. Meaning, if you've
got a 50hp and it's pushing an 1800lb boat, then you may never see more
than 28mph. Depends on how much work is involved?? Also, where's the
trim pin (speaking to the planing issue?). I'm with the earlier poster, as well,
37mph out of a 50 might be a tad bit of exaggeration....fwiw

 

[jerryjerry05]

Re: Force 50 running on 1 cylinder?

You can guess all day.You need to do the basics first.Compression/spark tests.
Then the fuel system.
Then if they are ok then get into the timing.Maybe the throttle isin't opening all the way.There is something in the reeds.The reeds broken,bent,missing.
You could be sucking air from a bad gasket.Start and then spray starting fluid around the motor.If it makes a difference then check that area.
Compression/spark test.J

 

[Frank Acampora]

Re: Force 50 running on 1 cylinder?

None the less, 37 MPH on anything more than a 12 foot tin boat is out of the question. The person smoking rocks was the one who told you he got 37 MPH. Hell! My 10 foot go-fast only does 45! And the 15 footer in the avatar with a strong running 105 only does the same.

On a 15 foot closed bow runabout, bow rider, or fishing boat, you would expect about 27 MPH. If you are swinging a 13.5 pitch prop at 4500, that's all you can expect out of that engine--Do the math: 4500 times lower unit gear ratio times pitch times about .90 (10% slip) will equal just around 28-30 MPH. Oh, if you port it and raise the compression, you may get 1 or 2 MPH more.

Do yourself a favor: Before you go crazy, experiment a little with the engine height on the transom. You may be able to get the cav plate about an inch above the bottom and still not have ventilation--then you will gain some speed.

There are no different lower unit gear ratios. If your lower unit was replaced, it will be the same---period. No difference in performance from the original.

People ALWAYS tell you to get the RPM up by going to a lower pitch prop. However, within constraints, you can't go fast without pitch and your experience of less speed at higher RPM with the lower pitch is common with Force engines. It is what it is.

 

[blueoval78]

Re: Force 50 running on 1 cylinder?

Thanks everyone for your responses. I am driving myself crazy with this issue because I am getting different opinions from various sources. My boat is a Bayliner Capri 1500; it is my first boat and I have nothing to compare against. I guess if I want more speed I will need to upgrade the motor. I just thought the boat felt kind of sluggish and it could do more. I am surprised Bayliner would create such a gutless setup.

 

[blueoval78]

Re: Force 50 running on 1 cylinder?

Ok, did some more experimenting today with the motor. I started it then proceeded to remove each spark plug wire. The motor is definetely running on both cylinders. I do have a question though, I pulled the plugs out to look at them. I currently have gapless plugs in the motor. Both were covered in a wet looking, oily, sooty film. Does this mean my spark is weak? Too rich fuel/air mixture? For weak spark, would it be the coils or further up in my stator, trigger or CDI box?