85hp alarm

[Dan]

I mounted the 85hp today and got it running, after sitting for 2yrs. Started fogging the carbs and got it to idle, then the alarm came on. The block did not seem to be to warm by the touch. The water pump seemed to be pumping fine out the pee hole. I'm going to pull the thermostat tomorrow, is there anything else I need to check out? Thanx

[jb123]

as long as your oil levels were ok, the the motor as most yamahas need plenty of water flow to cool them,as in the muffs sometimes dont cut it. to ensure it is a temp sensor, simply unplug the sensor at the head to break the alarm circuit.if it does not stop sounding it is elsewhere, either main tank or remote tank sensors.
also, the motor sat and carbs are gummed, definately break down the carbs to clean or your motor will not run correctly.

[Dan]

It doesn't have oil injection, is there any other alarms besides the temp? I imagine I'll pull the carbs down in the morning. The decarb fog was doing good, but I know its not enough. Thanx

[boats.net]

The 85hp is not oil injection the only alarm is overheat. If it sat for 2 years it's due for a water pump impeller replacement.

[Ken]

Dan,
Boats.net mechanic is right on everything he said. But if it were me, here's what I would do:
First - I would pull that thermo switch and test it in a pan of heated water with a good thermometer and ohm meter - it should close at around 180 degrees f., and reopen at around 160.
I have personally seen one on my C115 close at 135 degrees f., giving me a false overheat alarm.
Second - I would test the thermostat the same way - it should be fully open (.120") at around 135 f.
Third - I would do a shock treatment with SeaFoam or RingFree to see if that would clean up the carbs enough w/o an overhaul - probably won't, but worth a try.
Fourth - I would run the motor in the water and not on the muffs just in case the impeller is starving for water with the garden hose.
Hope this helps [img]smile.gif[/img] ,
Ken K

[Dan]

Thanx guys, I'm going to go pick up a thermometer and check it out.

[Dan]

Well I started out at my yamaha dealer. He said the same thing, impeller. I got that and a thermostat. I changed the impeller first and that did the trick. I fogged the carbs good with not that good of results. I went ahead and tore them down and cleaned and blew everything. There was not any trash and very little varnish in the bowels. But that did it, now its idleing around 600 rpms. What should it be idleing at? I'm going to the river tomorrow and try it out. By the way its swinging a 21 pitch prop and I have it mounted on a 15.5 skeeter f-80 bass boat. Is this to much prop? Thanx for the guidence, Dan.

[Ken]

Dan,
Glad you got her going - and 600 rpm for idle sounds a little low - 700 would be a bit better.
You really need to get a Yamaha shop manual for that 85 - it will pay for itself. You can order online at www.yamahapubs.com.
I believe the max rpm range for your motor is
4500-5500. You want to be about in the middle of that after you get up on plane and trimmed out to max speed w/o ventilation and porpoising. If you are outside of this range, then you need to change prop/pitch.
Good luck [img]smile.gif[/img] ,
Ken K

[Dan]

Good 700 rpms sounds better than 600. It sounded like I had a cam in a 4-stroke. It lopes alittle but I'm not through tinkering yet. I'll check their price against my local shop on the manuel. I've got a small library now on everything I've ever built. I'll know tomorrow on the rpms I'm running. I'd like to keep it around 5300-5500 WOT, I've got a 19 that needs a hub just in case. I'm going to give your friend a call this week about my 70. Thanx again.

[Dan]

Well it idled rough, but ran great. Cruised at 5000 rpm on plane. It porposed and cavitated just a bit now and again. I've got the motor set as high as it'll go. I'm going to drop it a notch tomorrow and try it again. On the air/fuel adjustment, which way is or rich/lean? I set all three back to original 1 1/8 out. Thanx Dan

[Ken]

Dan,
The proper height on the motor will put the cavitation plate riding just on top of the water when you are trimmed out. You don't want it down in the water, and you don't want it above it either.
All carbs are different on the pilot screw adjustment. On my C115, it is 3/4 turn out ccw from all the way in cw. The more ccw will give a richer mixture. You need that Yamaha manual for your model.
Good luck [img]smile.gif[/img] ,
Ken K

[Dan]

Yea, I know. I wanted to make sure that I was going to keep the motor before buying another manuel. Looks like I'm going to pick one up this week. Thanx again, Dan.

[Dan]

Any, idea what the cause of the rough idle is? I pulled the plugs, and they where tanish/brown. That sounds good to me.

[boats.net]

The pilot screws should be set at 1 1/8 turns on 85hp and should idle at 800 rpm's in neutral 600 in gear.

[Ken]

Dan,
If the motor runs great at high speed but idles rough, sure sounds like a low speed jet clogged up.
You might try squirting some fuel into the throat of each carb one at a time while the motor is at (rough) idle to see if you can isolate which cylinder isn't firing correctly. Or maybe pull a spark plug wire on each of the cylinders to see which one does not make a difference on the rough idle.
You are probably gonna have to clean out those low speed jets again.
Good luck [img]smile.gif[/img] ,
Ken K