Force 125: 2 Questions ??

[kwk]

I've got two questions about my 1989 125 HP Force on an 18' Wellcraft.<br /><br />1) The manual says the recommended RPM range is 4500-5500 RPM. However, at WOT mine only goes up to about 4000 RPM and the boat cruises at about 25 mph. I think it is the original prop, so it doesn't seem likely that is the problem. The engine runs and sounds fine all the way up to maximum speed.<br /><br />2) Occasionlly, when cranking the motor to start, it turns over for about 2 seconds and then stops cranking and just sort of hums. It usually ends up starting okay, but sometimes I have to work at it. Is this normal?

 

[JB]

Re: Force 125: 2 Questions ??

Howdy, Kwk. I'm not much on FORCE engines, but I think you are over propped. Try a prop with about 2" less pitch.<br /><br />You are describing symptoms of a weak starter or battery. Also could be dirty connection somewhere in the high current circuit.<br /><br />Good luck.<br />Red sky at night. . .<br />JB

 

[ODDD1]

Re: Force 125: 2 Questions ??

Kwk.. JB is right.. you need less pitch on the prop...just because it is original doesn't mean it is correct now....motor might be a bit tired, more likely the boat has gained weight over time...which will make it act the same way.......shoot for over 5000 rpm's with just you an a light fuel load in the boat.......

 

[kwk]

Re: Force 125: 2 Questions ??

Is there any harm in leaving it the way it is? Someone told me that these engines will last longer by not running them full out. By only reaching 4000 RPM at WOT, does that put less wear on the motor? How will the boat run at the same RPM with a lower pitch prop?

 

[kwk]

Re: Force 125: 2 Questions ??

Oh yeah.... How do I tell what pitch prop I have?

 

[my new fishmaster]

Re: Force 125: 2 Questions ??

Read the numbers on the prop should start with a 4 and the ending # is the pitch I am guessing you have a 17pitch or 15 like everyone says drop down 2 in the pitch department.

 

[ODDD1]

Re: Force 125: 2 Questions ??

Kwk, you HAVE to get the motor up in the recommended rpm range or you will damage it when running WOT.....overloaded motors overheat,detonate, and generally do evil things to pistons....fix it...

 

[lonewolf5347]

Re: Force 125: 2 Questions ??

i was reading yor speed and tach. reading compare to my 1994 120hp. on a 18ft. maxium aroud 2000 on tach. speed about 25mph.

 

[kevlar3000]

Re: Force 125: 2 Questions ??

If you are propped correctly then you have even more of a problem on your hand. Perhaps a compression check or a spark check. Your wot at normal range is crucial to the well being of your engine. RE your starter, it may be going out if it is just spinning freely. Not too expensive to rebuild. 50 to 75 bucks<br /><br />Good Luck

 

[walkingfish]

Re: Force 125: 2 Questions ??

Hi kwk,<br />This may or may not be useful to you.<br /><br />I have a 1989 Bayliner 1952 (19 foot Cuddy Cabin) with a 125Hp Force.<br /><br />I get up to 5500 revs (max, unloaded)and am doing close to 40 mph. (62 kmh = 39 mph)<br /><br />The prop i have is a 13.5 * 17 pitch, original 3 blade aluminium.<br /><br />Hope this gives you something to go on?!<br /><br />Cheers,<br />W'fish

 

[Rex]

Re: Force 125: 2 Questions ??

EVERYBOBY IS RIGHT BUT THE STARTER COULD<br />HAVE A WEAK SPRING WHICH WELL MAKE IT<br />JUMP OUT. IT WELL FIRE ONCE THEN THE START<br />JUMPS OUT.<br /><br />REX