1989 Force 125 Rough Running (HELP!!)

[walkingfish]

Hi all,<br />I am just new to this world of boating and have caught on to your web site "awesome".<br />You guys seem to know your stuff!!<br /><br />I have an 1989 Bayliner Capri (Cuddy Cabin)19ft with a 1989 Force 125Hp on the back.<br /><br />My problems are these,<br /><br />The Force idles smooth enough but when going slow (1500-3000 rpm) there is a reasnobly strong "shudder" from the engine.<br />This goes away after about 3000rpm and the engine again runs smooth?!<br />My prop has been smoothed so there are no noticible marks or chips and i only run 97 Octane gas at 50:1 with good oil. My motor has just been serviced, and compressions are good.<br /><br />Also top speed is at about 34 Mph is this standard?, it gets out of the hole quick and revs up to 5500 with no strain.<br />I have a 13.5 * 17" prop.<br /><br />Any advice would be great as i tend to worry about these things untill i hear from someone with some knowledge.<br /><br />Ps Most of my fun will be had in the Sea as i live at the Bottom of New Zealand, any advice on sea use?<br /><br />I look forward to hearing the advice of those more experienced.<br /><br />May your lines be tight and your buckets be full.<br /><br />Brad

 

[cyberplumber1]

Re: 1989 Force 125 Rough Running (HELP!!)

I have a 1989 Force 150 that does the same thing and it has been COMPLETLY rebuilt. I"m talking about everything under the hood. Mine will idle smooth then all the sudden it has a chudder like a small seizer. Sometimes it even kills the motor.I have been told by some very good boat motor mechanics that the 1989 Force 150 is a peice of s**t. I agree, i just wish they would have told me that about $8,000 ago.If you motor is rough up to 3000 rpm"s check your plugs and your carbs because for some reason or other you are not running on all cylinders until you reach a certain rpm. The bst thing to do is take it to a certified Force mechanic and have him set the carb float levels and so on. GOOD LUCK

 

[sony2001]

Re: 1989 Force 125 Rough Running (HELP!!)

walkingfish; I have the same package from 1988. Here are a few easy suggestions: 1 There is a black tag in the engine well listing the octane at 85 so try to use or mix to get up to 89. More isn,t necessary and could be counter productive. <br />2 Give the engine a decarbonization treatment<br />using a set of old spark plugs. <br />3 Force apparently sent out an advisory that<br />Wide Open Throttle should be set at 30 degrees BTDC not 32 as in manual.<br /> Every piston engine has a RPM zone that causes a greater shudder, some so much that the manufacturer insist you don't stay there.<br /><br />------------------

 

[sony2001]

Re: 1989 Force 125 Rough Running (HELP!!)

Oh yes, I'm running a 19" prop and am very happy with it. At 5500 rpm you are at max.<br />mfg. recommended. So a 19" would insure no overreving.<br /><br />------------------

 

[sony2001]

Re: 1989 Force 125 Rough Running (HELP!!)

The advisory was issued due to the useage of a lot of low grade gasoline. Best keep the design specs of 32 degrees BTDC.<br /><br />------------------

 

[walkingfish]

Re: 1989 Force 125 Rough Running (HELP!!)

Thanks Guys,<br />Sony, you have the same package right, so how fast does it go and how quick does it get there?<br />Does it tow a skier? Any problems?<br />Also what is a De Carbonization process? any helpful links to the web on this?<br /><br /><br />Cyber,<br />The shudder i have doesn't seem likely to kill the engine but it is constant at low revs.<br /><br />I have had people tell me it could be a loose earth wire on the coil pack?<br /><br />Also my rev counter "drops off" every now and then and then starts back up for no reason?<br /><br />What about crap in the carbs, do they have two jets in each carb and the smaller ones could be blocked?<br /><br />Thanks again for your help!<br /><br />Brad<br />Invercargill<br />New Zealand

 

[evin300]

Re: 1989 Force 125 Rough Running (HELP!!)

If I read your post correctly, you are relatively new to 2-stroke engines? I had a similar question for my mechanic years ago, and This was my second outboard. As I slowly accelerated the motor I reached an RPM range similar to yours and the motor would feel rough, it would just shake and you could feel it in the whole boat, as I accelerated more it went away, and was completely fine at all other times, I was told that my carb uses low speed jets and high speed jets. There is a transition that occurs from low to high and if you hold the rpm right at this transition zone you are feeling the battle going on between the two jets and this sounds exactly like what you are feeling. Also I would go to a dealer to find any update bulletins for your motor, which could include recomended fuel and even a hotter plug as was recomended just a couple of years ago for my Evinrude V-8. I am sure that your Force is not a POS. I am sure they used the same quality aluminum and steel to build this motor as any other. It may have some quirks but I would bet that its service life would be the same as others. As far as your prop goes it sounds like its perfect, you want to run a 2-stroke at the upper end of its RPM range for maximum HP and the overall health of the engine. Low RPM at WOT=BAD!! When it comes to the speed of your boat it seems ok, But there is only one way to confirm, and that is to do a propeller slip calculation. Mercury offers a propeller slip calculator for a few bucks and it is really neat. You need to have the RPM at WOT, The pitch of the propeller, and the gear ratio of your lower unit. This will tell you just how efficeint your prop is working, to much slip and you are just wasteing your horsepower, also always check the condition of the bottom of the boat for smoothness. And lastly if you really must have the best performance possible then a Stainless Steel propeller is a must. Even the thinner bladed (cheaper) models could prove to be the best. OMC makes a SST line of props (that might even fit) The main advantage of SS is that the blade can be made thinner with the same amount of strength, and that is free speed and power (not exactly free)lol. The prop is THE most important part of your package and definatey worth the time and hassle. Many dealers will let you try different ones. Hope this helps, and I hope you enjoy your new hobby, I sure have!

 

[sony2001]

Re: 1989 Force 125 Rough Running (HELP!!)

Walkingfish; I have the 1988 Bayliner, cuddy cabin, 18.5 feet that indicates 34 mph at WOT with trim down. It gets there very quickly. For skiing stick with the 17" prop. To decarbon once to twice a year get familiar with Merc Power Tuner. An aerosol for the carb venturis that makes its way thru the system, engine runnig. Then overdose it to a stall, let sit 15 minutes and restart to purge the system. There is also an in tank cleaner for the jets called Seafoam or Valvetec. With the aerosol I hold my breath and stay upwind!<br /><br />------------------

 

[sony2001]

Re: 1989 Force 125 Rough Running (HELP!!)

The last and most expensive proceedure is to have the jets blown out or washed with the decarbonizer to remove the small amount of gas that has varnished the openings. Find a mechanic that doesn't badmouth Force and you may avoid a self fulfilled prophecy!<br /><br />------------------

 

[walkingfish]

Re: 1989 Force 125 Rough Running (HELP!!)

Thanks for all your help!!<br /><br />I will give these ideas a go and post a reply to let you know how its gone,<br />by the way i am new to this world of boating and its great to find a community like this to ease my fears.<br />Thanks again.<br /><br />Brad

 

[jimdi@localnet.com]

Re: 1989 Force 125 Rough Running (HELP!!)

Just had my force 125 rebuilt and after had the same problem - good idle - good high - rough middle. Turned out I was losing spark on #3 in mid range. Mechanic switched out all electric componets and found that a faulty pack on #1&#2 was causing problems with the #3 cyl. He doesn't know why this fixed the problem - but it did. <br />Runs smooth low to high now.<br /><br />jim<br /><br />(put it at missing range and pull plug wires. when you find one that makes no difference - that is the cyl that is not firing.

 

[sony2001]

Re: 1989 Force 125 Rough Running (HELP!!)

The key was that your rev counter would go wild during the shuttering of the engine. Problem was electrical causing the loss of one cylinder. A few posts back they say a bad CD can affect another if the isolation diode is defective.

 

[DJestes]

Re: 1989 Force 125 Rough Running (HELP!!)

I also own a 1989 125 HP force and at about 2000 or so the motor gets rough and hesitates until I get to about 3000. Under no load the hesitation does not exist would the CD unit be the culprit? My top speed is 35 at 5000 with a 13.5 x 15 prop.