Force Outboards Rated By Model

kalebsheridan

Petty Officer 2nd Class
Joined
Aug 14, 2023
Messages
129
No all 85 and 90 Hp are 3 cylinders with three carbs.
The one carb 70Hp from 1991 and up with Chrysler/Force power head and Mercury gear case is a 3 cylinder engine.
The 85 and 90Hp are good engines, old school design (cross flow chargning)
from the 60.es and with newer electronic ignition system (Prestolite or Thunderbolt).
Maintain them and do not lean the air/fuel mixture less than 1 turn out from seated and they will run for a long time.
Remember these engines are 25 years or older so run them with care, do not run the hell out of them.
Okay cool! I see lots of those US marine 85hps kicking around my area for super cheap. I was wondering about those if I ever wanted more power. Yeah definitely going to take it easy. Does that "one screw turn out" advice apply to the same year 50s? That's what I have and I'm terrified of leaning it out.
 

Nordin

Commander
Joined
Jun 12, 2010
Messages
2,456
1-1,5 turn out from seated is a general setting for two stroke OBs.
Some engines need up to 2,5 turn out from seated.
The carbs who are mounted at Chrysler and Force OB are Tillotson or Wallboro brand and the low speed circuit in these carbs is acting at high speed too.
If you have the air/fuel mixture screws adjusted less the 1 turn out because you get a better idling then you can melt the piston when running at high RPMs.
The cylinder will run lean cause of a lean air/fuel mixture screw.
1-1,5 turn out from seated applies on your 50Hp.
 

kalebsheridan

Petty Officer 2nd Class
Joined
Aug 14, 2023
Messages
129
1-1,5 turn out from seated is a general setting for two stroke OBs.
Some engines need up to 2,5 turn out from seated.
The carbs who are mounted at Chrysler and Force OB are Tillotson or Wallboro brand and the low speed circuit in these carbs is acting at high speed too.
If you have the air/fuel mixture screws adjusted less the 1 turn out because you get a better idling then you can melt the piston when running at high RPMs.
The cylinder will run lean cause of a lean air/fuel mixture screw.
1-1,5 turn out from seated applies on your 50Hp.
Okay awesome, I'll be sure to double check before I take my motor out next. Like you said, it idles really nice but I'm pretty sure it's under that 1-1.5 turn threshold (haven't taken out on the water since then). Last I remember it idles okay, but not great at 1.5 turns. Is that typical? Or does my carb need some more cleaning or something? I will have to double check of course, but it does idle poorly at 1.5 turns, would that constitute some kind of issue?
 
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