Force 125 what to expect?

[Kevincem]

I have a 1988 Force 125 (1251X8A). The motor is on a 19’ Bayliner Capri open bow. I have two props one is a 14X13 and the other is a 13.5X17. I only get 4500RMPs with the 14X13 prop with a top speed of 25MPh by my boat speedo. With the 13.5X17 prop with WOT my RPMs are 3900 with a top speed of 30MPH. Is this normal? I can hardly even pull a skier. I wouldn't even try with the 13.5X17 prop. They would never get up. The engine sounds like it is running good. I have cleaned the fuel filter, decarboned the engine, checked timming and have put in new pluggs. The engine sounds good. Is there anything else I should do? Also I am in SLC Utah Elevation 4226 ft. Would this have something to do with the performance I am seeing?

 

[roscoe]

Re: Force 125 what to expect?

The elevation is going to start having an effect at that level. Jets in carbs probably need to be changed a size or two.<br /><br />These motors can sound pretty good on 3 cylinders.<br />Have you actually checked to verify that each cylinder is firing?<br />And have you checked the compression?<br /><br />I would check these out before making any decisions.

 

[kwk]

Re: Force 125 what to expect?

Roscoe is right.<br /><br />Check to make sure you are firing on all cylinders. I've been having low RPM problems with a 1989 125 HP Force on an 18' Center Console and keep tracing the problem back to bad ignition coils. I've had three go bad now. The engine generally sounds fine running on 3 cylinders, except sometimes it would die as it went into gear. It was losing anywhere from 800-1000 RPM by dropping the cylinder. I also found my tachometer was reading about 15% too low and replaced it.<br /><br />I spent a lot time investigating props while working on the low RPM. Just for reference, and I don't know the diameter, but a 17" pitch turned 4600 RPM at 30 mph, 15" turned 5200 RPM at 30 mph, and 13" turned 5500+ RPM at 25 mph. I kept the 15" prop.

 

[Kevincem]

Re: Force 125 what to expect?

I checked the compression and all 4 cylinders had 125. What should I expect? I also took the spark plugs out and made sure that I was able to get a spark. I did this by just putting the spark plug close enough to the block that the spark would jump. Is this a good way of checking the spark? I also cleaned all of the plugs before replacing them. Does getting a spark mean I have good coils? <br /><br />Thanks for everyone’s help. It has been a great. This is my first boat with anything more than a 3 HP motor.

 

[roscoe]

Re: Force 125 what to expect?

125 is pretty good compression for a motor of that age, It was 145-160 when new. And all cylinders measured pretty close to each other? Thats good too.<br /><br />Spark should jump a 1/2 inch gap from the plug to the block.<br /><br />Your coils appear good, but may not contiue to provide spark when they get hot, after being used for a while. You might want to check them again after you run the motor for 15 minutes.<br /><br />Also remember that your boat, motor, fuel , and battery weigh over 2000#. That is quite a bit for a 125hp motor to push around. The hull alone weighs close to 1700#.<br /><br />If the motor is running properly, then concentrate on propping the motor so that you can reach 4700-5000 rpm at full throttle.<br /><br />The lower the pitch, the higher the rpm, and the better the holeshot and pulling power.

 

[wvit100]

Re: Force 125 what to expect?

I had a '89 125 force on a 19" cuddy cabin bayliner and could get right around 40 mph with 2 or 3 people in the boat.

 

[Kevincem]

Re: Force 125 what to expect?

I found that the plastic coating on the ground wire that runs back to the controls is melted. This makes me believe that the problem lies in the electrical system. How much would a new set of coils set me back? Could it be the power pack? What is the best way to check the spark again after running for 15 min? Is there a way to verify that the spark is consistent? Also I just bought the boat and really don't know the history all that well.

 

[roscoe]

Re: Force 125 what to expect?

Coils are $46 a piece, ouch.<br /> http://www.maxrules.com/fixforcelectric3.html <br /><br />For obvious reasons, you don't want to start throwing money into parts until you can find out what is wrong.<br /><br />The way you are checking for spark is ok, there are also spark testers you can buy, and some guys here have made their own.<br /><br /> http://www.iboats.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=17;t=022104#000001 <br /><br /> http://www.iboats.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=17;t=021097#000001 <br /><br /> http://www.iboats.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=17;t=007690#000001 <br /><br />???<br /><br />I'm thinking that carb work may be in order, but not sure.<br /><br />Not to chase you away from iboats, but there is a real knowledgable Force mechanic out there on the web. His website is www.themarinedoctor.com<br /><br />Perhaps he can advise you in some other area that I don't know about.