1997 Force 120 hp

[jefftrivett]

I have a 97 force 120 on my Bayliner. The motor runs really well to you reach 20mph. When I push the shifter forward to go faster I feel it jerk in the motor. This boat and motor dont have many hours on it. Can you make a suggestion of what my problem maybe.

 

[emoney]

Re: 1997 Force 120 hp

Could be a lot of things. I suggest you share a little more info. Does it keep building RPM but jerks? Is 2k rpm the max or?? There's another thraed below this one with a video, is your motor acting like that one. Give these guys as many details as possible and they'll help you.

 

[jerryjerry05]

Re: 1997 Force 120 hp

What kind of prop/hub do you have?
If it's the old style with the rubber hub,it could be slipping???
Probably not but hoping for the cheapest easiest fix.
If it starts to jerk and jump under load.
It's possible the shifter needs adjusting.
Or more likley the clutch dog is worn.Possibly the forward gear.
That can be fixed by taking out the dog and turning it around or resurfacing the teeth.
The dog is a bit softer metal and it wears first before the gear.
Don't let this go as it will only get real bad and more costly.
Lots of time this is caused by shifting into gear slowly.
This is one thing that needs to be done smooth and fast,right into gear.

Post a pic of the prop when you have it off.
Older prop?Mark it across the rubber hub and then go for a ride and see if the mark moves.

 

[jefftrivett]

Re: 1997 Force 120 hp

What kind of prop/hub do you have?
If it's the old style with the rubber hub,it could be slipping???
Probably not but hoping for the cheapest easiest fix.
If it starts to jerk and jump under load.
It's possible the shifter needs adjusting.
Or more likley the clutch dog is worn.Possibly the forward gear.
That can be fixed by taking out the dog and turning it around or resurfacing the teeth.
The dog is a bit softer metal and it wears first before the gear.
Don't let this go as it will only get real bad and more costly.
Lots of time this is caused by shifting into gear slowly.
This is one thing that needs to be done smooth and fast,right into gear.

Post a pic of the prop when you have it off.
Older prop?Mark it across the rubber hub and then go for a ride and see if the mark moves.

Jerryjerry, thank you for your help.I had purchased a new prop last year and too the boat at twice. I figured when it started jerking that it was something major. However, there was a defect in the prop which caused the hub to be spun when under a load. The marine replaced it for free and it runs great now. I would have never thought to look at the prop or hub because it was new.

 

[emoney]

Re: 1997 Force 120 hp

Good for you, Jeff. They used those "Flo-Torq" hubs and the center part is plastic. It's actually a good thing, because instead of it tearing up the gears if you hit something or get rope wrapped around the prop, it sacrifices the plastic hub. Those things are only $20.00 while you don't want to ask how much the lower unit is. Happy and safe boating!!!