1989 suzuki 85dt lack of power

[waffles1]

I have a 85dt suzuki on a Southfork 18' aluminum bass boat full v bottom. The boat and motor weigh around 1000 pounds. The motor has a slight miss when idling but other then sluggish performance doesn't sound bad when you hit full throttle. Compression on the three cyclinders is 125, 125, and 115. The gas is new. It has a new 13.5 x 19 propeller. I just had it in the shop and the high jets were adjusted. It will not pull a skier and top speed is around 34 mph. Any advice?

 

[waffles1]

Re: 1989 suzuki 85dt lack of power

It also has new plugs and the old ones looked clean. Spark looked strong on all 3 plugs. When running full throttle I also tried pumpimg the fuel bulb on the gas line to make sure it isn't a fuel pump problem or an issue with the motor starving for gas. I did the same thing when idling and the miss didn't change. It had no effect. Could the timing be slightly out? On this motor are you able to adjust the timing and if so, how? Any help or advice is greatly appreciated. Thanks.

 

[JUSTINTIME]

Re: 1989 suzuki 85dt lack of power

i would buy a manual
a slight miss?
was it sneezing?

 

[bowhuntrrl]

Re: 1989 suzuki 85dt lack of power

I run a 13.5x15 prop on my DT-85 and a 16' fiberglass center console. Mine came with a 19 pitch and would barely plane the boat. To pull a skier you will need to drop down in pitch. Without a tach, it's impossible to correctly prop a boat. My WOT is 5400 rpm. Yours should also be in that area 5400-5500. You may not necessarily gain speed but you will gain power. You should also straighten out the miss, maybe clean the carbs.

 

[waffles1]

Re: 1989 suzuki 85dt lack of power

No sneezing. I previously had a 13.5x17 and had the same problem. The carbs were cleaned by a dealer. Once I hit the throttle the miss goes away from what I can tell and it sounds smooth and with two or less people planes ok. It just seems that it doesn't have the power it used to. I am wondering if the timing is off just a bit or not advancing as it should. I know that the throttle linkage has been moved and I was told that effects the timing. Is that true? I have a manual but I am not sure which one I have. I am just trying to get all the experienced advice from you guys before I dig in. I really appreciate your help. I do have a tach and believe it hits around 4500-4800 at peak performance. The boat and motor weigh around 1000 - 1200 pounds max. Thanks.

 

[bowhuntrrl]

Re: 1989 suzuki 85dt lack of power

I do have a tach and believe it hits around 4500-4800 at peak performance. The boat and motor weigh around 1000 - 1200 pounds max. Thanks.

That right there proves that you are over propped !!! You should be getting about 5500 rpm at WOT. The other possibility is an engine problem preventing it from achieving top rpm.

 

[waffles1]

Re: 1989 suzuki 85dt lack of power

This motor came from an older boat that had a 13.5x15 prop and the rpms didn't change when I went to the new boat and new prop. The dealer said the boat would be a little slower coming out of the whole but should have no problem with that size boat and motor pulling tubers and skiers. Going back to the "unless I have an engine problem" is why I was asking about the timing not advancing. I may go ahead and put the old 13.5x15 prop back on but it is beat up a bit and I am not sure if that would be a true test. I appreciate your input and if you think it may be anything else or still think it's a prop issue please advise me.

 

[bowhuntrrl]

Re: 1989 suzuki 85dt lack of power

The throttle linkage does affect the static timing and if it was moved I suppose it could contribute to your problem. My DT-85 is an '86 and doesn't have a throttle position switch as yours may have.Have you checked that?? Really, without following some of the diagnostics in the manual, it's unlikely that we'll ever get anywhere. My advice is to check out the static timing procedure in the manual and make sure that you are ok.When I bought mine, it had similar problems that I fixed by rebuilding the carbs and fuel pump, changed the plugs and checked the timing, replaced the engine filter and water separator, and installed a tach and re propped my boat. Honestly, if your boat is as light as you say, a 17P prop should be good. I'm starting to lean towards some sort of engine glitch holding you back.

 

[waffles1]

Re: 1989 suzuki 85dt lack of power

Thanks. I will do as you advise. It may take a couple of weeks before I can work on it but I'll let you know. Thanks for your help.

 

[bowhuntrrl]

Re: 1989 suzuki 85dt lack of power

Thanks. I will do as you advise. It may take a couple of weeks before I can work on it but I'll let you know. Thanks for your help.

Tell me about it !!! I haven't had time to work on my boat to clear up a few problems. I haven't been in the water yet this season.