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DT85 problems after sitting 4 years

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bowhuntrrl

Contributing Member
"Ok, here's what I've

"Ok, here's what I've done so far to fix a stalling problem going into gear on my 1986 DT-85 that sat for 4 years. Checked compression: all between 130-135. I rebuilt the fuel pump, rebuilt the carbs, and checked the oil pump timing.Cleaned out the oil tank and replaced the oil with a Synthetic blend . I set the air/idle jets to 1 1/2 turns per Clymer manual after cleaning/rebuild.The float levels were right on the money.The engine started like a champ and seemed to idle ok although the engine put out a lot of smoke and seemed rich.

Took it to the lake and still stalled going into gear. Seemed like the idle was low, so I set it up a bit. That seemed to fix the stalling, but then we had a new problem. Engine started to run on 2 cylinders (top not firing) when put into gear . Pulled the plugs and put in 3 new NGK B8HS plugs. Started it up again and fouled the top plug again. I opened up the top carb idle jet to 2 turns. Cleaned the fouled plug and switched cylinders with plug from middle cyl. Started it up again and let it idle. Seemed to be running on all 3 cylinders. I waited until the thermostat opened, then put it into gear. It immediately started to run on 2 cylinders as soon as it was put under load.

Pulled it out of the lake again and checked the plugs. This time, it was the middle cylinder that was fouled. This was where I had moved the plug previously. My thought is that it's a bad plug. I have had really bad luck with NGKs in the past with snowmobiles and absolutely detest them. I wish I could use something else.

Anyways, 2 things: It seems like a bad plug since the cylinder fouls where ever I move the plug to.

The other thing: Before I took the carbs apart, I marked down the air/idle jet turns to closed. All 3 were different and considerably different from the manual specs. Should I try these settings rather than the 1 1/2 turns called for ???

One other thing: The engine is an '86 by serial, but by the characteristics and features, it looks like an '87. The air/idle specs on the '87 are quite a bit leaner on the 1987 model.

No where in Clymer does it mention to adjust the air/idle jet after a carb overhaul, merely set to the spec. This seems odd to me since this adjustment is always tweaked for best idle on any other motor that I've ever worked on. What's the deal with that ???

This project is getting old as the season for fluke is over soon and mama wants some to eat !!!! Any thoughts on my dilemma ??? Thanks."
 
"Hi Rich

If you are having

"Hi Rich

If you are having trouble with different individual cylinders it smells a little like carb/fuel problems still. When the outboard is put in gear, it opens the throttle a little and the fuel air delivery path through the carbs is different. One check (you have probably done as you are using a manual) is to check that all 3 throttle plates open at the same time (synchronisation) Easiest way to check it is solder a short wire to 3 small crocodile clips, clip each one to the shaft the throttle plate is mounted on and operate the throttle. All the wire indicators should start to move at the exactly same time. If not it is important to correct this.
An old hand once checked out the idle mixture on our sea rescue boat by idling for two minutes and then going into gear and throttling up while securely attached to the pier. As two strokes hold a charge of fuel air mixture in the crankcase the amount of smoke in the exhaust in gear initially will give you a guide of how rich the mixture in idle was. A minor adjustment was made to all carbs. Word of caution though,if you are having trouble with individual cylinders be careful its easy to damage the engine.
PS Your model of engine has a tendancy for the foam sound insulation on the outboard cover to deteriorate. It breaks off tiny pieces which then get sucked ito the idle air passages. check the condition of the foam.

Good Luck
Sirlespat
Now googling to find out what the heck a fluke is!"
 
"Sirlespat,

Fluke=summer fl

"Sirlespat,

Fluke=summer flounder (flounder with teeth). They are to me, like a mini halibut. Then can get up to the 20 pound range. Around here (Massachusetts) anything over about 5 lbs is considered a "doormat". This season, lots of folks are catching them from 9-14 lbs. They are mighty fine eating, right up there with the best !!!

I think we had a bad plug since the problem moved to the cylinder we switched one plug to. Due to weather and commitments, I wasn't able to try it in the water this weekend, maybe tomorrow. Anways, I put a new plug in to replace the suspected one and leaned out the idle jets to 2 turns. I will let everyone know the outcome. It seems that the stalling in gear was a low idle adjustment. The darn screw wasn't even touching the bracket !!!!"
 
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