1982 DT85 Problems Help

[boroman]

Hi

I have been having a number of problems with my DT85

FIRST: When I ran it up on the drive way in a tank it reved fine and idled ok. I took it to the water, started it up ok then when applying throttle it would not get above 3-4 mph and bogged down. I have read all the threads so I decided to get it in for a service, I told the guys at the center that the engine bogged down and would need the carbs cleaning.

The engine was serviced, new impellor, oil , plugs and a plug cap. Guys tried to set it up and said it idled fine yet they were unable to get it to run correctly under load. They belived that it could be a problem in the crank case causing loss of suction?

Before performing open heart surgery on such an old motor i decided it would probably be best to trace the motors history and to follow advice on other forums and clean the carbs my self, including soaking, blowing and replacing gaskets etc. At this time I have also replaced the fule pump diaphragams and renewed the fuel hose and tank.

Motors history shows that the labrynith seal had failed a couple of years ago and the motor was stripped and repaired by a reputable marine service company. Since that date the motor has done 15-20 hours only

I have rebuilt the motor and tried to get all the links back the same, however now that all the carbs are providing fuel correctly things are not right. Managed to start the motor using choke ran for a very short amount of time and died.
I set all the air screws to recommended settings in the Suzi manual 1.1/5 turns from soft seat.

The motor ran for a couple of min then seamed to drop its idle speed and die. When i tried to start again it did not want to know, it coughed and spluttered and a few backfires.

I watied till cool then choked and started the motor ok, I adjusted the note of the engine (rev counter not working) using the advance as per the manual. The motor now ran for longer and I was able to apply throttle using the Warm up lever and it reved freely. Eventually the motor slowed down coughed and stopped.

Am I heading in the right direction? I have the wiring details for the rev counter now and will attach and post results as I will work on it tonight.

Hope you guys can offer some pearls of wisdom, we have summer and over the last few years this has been fleeting in the N.E. Uk

Thanks

 

[waffles1]

Re: 1982 DT85 Problems Help

If it is coughing that sounds like it could be starving for fuel. The backfire could be from that also or the timing not being correct. I would go ahead and open the screws up to 11/2 and see what difference that makes. If nothing changes then check your timing. I am assuming the compression did check good on all 3 cylinders? Good luck.

 

[boroman]

Re: 1982 DT85 Problems Help

Hi

Update from last nights tinkering.
Played with the engine last night having read several forum threads regarding set up.

Adjusted the needles as per the manual for set up, started the engine and it ran ok bit low on revs so adjusted the advance bolt at side of engine. Engine settled out at smooth revs.(NOTE at this point i did the remove the plugs check, as soon as I removed the top plug the engine cut out, put it back and started again, the other two made no difference)Then I noticed the second carb was spraying fuel from the main jets like a little fountain, this was running down the front plate and going into the bottom carb.
Ok so I dismantled the 2nd carb again and adjusted the float in a couple of mm. As I was replacing it I thought the bottom carb also looked a little to wet, so I dismantled this one and found something very strange, the needle valve housing had backed out by a couple of threads. I thought you dozy git I have not tightened it down right. So I put this right, set the float to the same as the other carb and put it back.


I started the engine and it ran the same as before but there was no more fountain in the mid carb and the third looked good to. So I primed the fuel whilst it was running (as advised to eliminate fuel pump issue) then all of a sudden the engine accelerated I noticed that the top carb was now spraying fuel like a fountain. So I removed and checked this carb float. When I opened the housing to my surprise the needle valve housing had backed out by three threads? Now as this is the only cylinder driving the engine the carb was good. I can only assume priming the fuel whilst it was running caused it? Any way sorted this out then ran the engine again, it ran smooth and revved using the warm up on the control box. Did the plug thing again same thing happened.

So I removed the plugs, the bottom two plugs were very wet, not overly familure with two stroke spark plugs but the liquid on them was very dark and it was the same for both. I can see where Service may have got their diagnosis (Crank seals causing loss of suction in crank case so engine not drawing in fuel) however, with the plug out I turned the motor by hand, the blow and suck was good (on both pots) and i did notice a bit of a mist come out. If the engine was not sucking as service surmised then the pots would not be wet would they?

Is it possible that the bottom two pots were just flooded after all the fuel the carbs had sprayed into them? Do you think it could be a timing issue? I did not have time to check the spark again however prior to service I had a good blue spark on all of the plugs, I will do this tonight and let you know how I get on.

Any advice from you suzi experts would be greatly appreciated, summer is here and time on the water will be fleeting please help/