85hp runs strong, but noisy.

[Mark42]

Ran the 1985 85hp Force for two weeks on the Peconic bay two weeks ago. It ran well, starts with just a bump of the starter, idles great (smokes a lot at idle - using Mercury or Walmart tcw3 oil) and when the throttle is opened up, it comes on strong.

There are two issues/questions I have:

1) It doesn't like to come off idle and run smooth when the throttle is opened very slowly. It seems to like the carbs to open at least by 1/3 throttle. After reaching cruising speed, the throttle response is good to small changes in throttle. It just doesn't seem to like a slow off-idle accelleration. Carbs were off and are clean as a whistle. Is this just the nature of the beast?

2) When the motor is running at higher speeds, it makes a lot of mechanical noises. A lot more "lose" or "ratty" sounding than my 93 Johnson 40hp twin (only reference I have). Makes me a little nervous to run the motor WOT because it sounds like its ready to munch a bearing or something. Are these things just noisy by design?

 

[RRitt]

Re: 85hp runs strong, but noisy.

my 85's have smooth power curve throughout band. But the actual power of my 85 is more like a 70-75. Someone mentioned that Force used an older standard for HP rating that inflates rating by 15% so that made sense to me and I never gave it much worry.

Mine are very noisy but 90% of the noise is from carbs. With twins at WOT it was hard to hear anything over engines. If there is any mechanical clanking it is drowned out by noise coming from carbs. There is a ton of noise coming out of the carb throats. When I was younger I had a Datsun 2000 with twin sidedraft SU carbs (sweet little car, best ragtop I ever had). It was similar in that each cylinder had a barrel with direct throat to valves. It made the same type of noise and air filters had a huge impact on noise level. I never tried putting air filters into force but it might cut noise down to your johnnyrude levels.

I took some contact cement and lined the top cover with 3/8" closed-cell neoprene. That cut the noise down substantially and made it tolerable. Still not what I would call quiet but at least it is possible to have somewhat of converstation while cruising out the the holes.

just a thought but maybe mixture is off. That could make pinging/knocking noise at WOT and affect your power curve.

 

[Mark42]

Re: 85hp runs strong, but noisy.

My 85 has three carbs with a large intake housing connecting them all together. It bends around in a U shape so the open end of the intake faces forward. Could be amplifying the carb noises. There looks to be enough space to add a little sound deadener to the intake. Might give it a try.

I'll also check the jets, they could be way off making off-idle accelleration "stumbly".

Any luck on reducing the smoke at low RPMs? Someone here mentioned that synthetic oil helped reduce smoke.

 

[Nate3172]

Re: 85hp runs strong, but noisy.

Try checking your fuel recirculation system. Make sure the reeds are closing by blowing back through the hose that goes to the intake from the recirc. plate. If you can blow back towards the recirc. plate than one or more of the reeds are no longer seating and should be replaced. If that checks out than remove the reed plate and clean the screens out so the fuel can actually be recirculated. This cured all my heavy smoking at an idle with my 85hp and also improved my acceleration dramatically.

 

[Mark42]

Re: 85hp runs strong, but noisy.

Thanks Nate. Great info.