8o model suzuki 85hp outboard

[pick]

I have a 1988 challenger 17ft bass boat with 85hp suzuki motor. The boat will only run 28mph turning 38-3900 rpm.3900 rpm is the most it will turn. Does anyone have any sugges. on getting faster topend speed out of this motor.

 

[Bifflefan]

Re: 8o model suzuki 85hp outboard

Well you need to post the prop pitch that you have now.
Either you are way over prop'd or you have an engine problem.

Read this link.

 

[pick]

Re: 8o model suzuki 85hp outboard

thanks for the reply the prop pitch is 13 1/4x 17

 

[steelespike]

Re: 8o model suzuki 85hp outboard

Prop sounds right on.Do you trim up and does the boat respond to trim.
Is boat fiberglass or aluminum? Is the bottom clean and smooth?Prop in good shape.
As far as the motor be sure the throttle opens all the way at the carbs.Check that it is running on all cylinders.Properly timed.You could do a compression check noting the condition of the plugs and their location.

 

[pick]

Re: 8o model suzuki 85hp outboard

yeah i trim up bottom is smooth fiberglass tri hull when I go down lake turning bout 3900 sometimes boat will pop sometimes it runs fine. Had compresion check done it was good new plugs had carbs took apart and cleaned could it be water in gas makeing it pop.What octane gas should i use. The motor has like maybe ten hours on it my grandfather boat and never used it much. The boat and motor looks like it just rolled off show room floor.

 

[steelespike]

Re: 8o model suzuki 85hp outboard

Most outboards run on 87 octane.When you trim up does the boat respond.
Bow comes up and speed increases?The anti vent plate just above the prop should be visable on plane. Usually about an inch above the bottom of the boat.
Something is way off.Should be running at least 5,600 rpm probably 40 mph.
Your 1700 rpm low.A 1" change in pitch will raise or lower rpm "about" 200 rpm.
I think you can see you would need to reduce your pitch 8" to approach 1600 rpm increase That would put you at about 9" pitch, smaller than you would use to push a big pontoon or a small house boat.
You need to confirm that the hand throttle opens the carb(s) all the way.Popping could indicate it is running lean. Try tickling the choke/primer.
Don't assume because it is a low hours motor that throttle and timing were ever right.If I'm not mistaken you have 3 carbs these need to be syncronized together and with the timing advance.

 

[pick]

Re: 8o model suzuki 85hp outboard

boat responds to trim havent look at the plate i will next time i get on the water though im going to check the throtle. Do you think I should change props. Also do you think the carbs need alittle adjusting i forgot to tell you the boat is real cold natured . I dont know much about this stuff this is my first boat so you will have to excuse me for being so dumb on the boat stuff. Thanks alot for the help so far.

 

[pick]

Re: 8o model suzuki 85hp outboard

ok just checked carbs they all seem to be opening all the way open. Dont know if this maters but took the plugs out all three are really black like fouled black. the guy that works on my boat is a merc man i dont know if a merc man. Does a merc and suzuki adjust the same as far as how rich and stuff like that or is all outboards the same. On the choke deal when it starts poping i can bump choke and it will get better for alittle bit then it will do it again. sometimes i can stop and fish a minute then start to take off and it will bog down sometimes it will die but when it starts to die i can bump choke and it will take right off.But as far as popping at full throtle sometimes it does it sometimes it will run fine. thanks for the help need all i can get thanks alot

 

[steelespike]

Re: 8o model suzuki 85hp outboard

Is the motor a DT85?My old aftermarket manual says they run a NGK B8HS plug
set at .035.This part number may be superceded now but would be the same heat range.Your symtoms seem to indicate a lean condition yet your plugs appear like too rich. You may have a combination of problems.Weak or poorly adjusted ignition and
a lean condition Could be fuel pump,or carbs.Responding to the choke is a classic indication of being lean.It might pay to try to find a Suzuki guy because he might have first hand experience with the DT85.
I think I would start by having the ignition checked.There is a tool to check the spark .Spark should jump at least 3/8".There is a timing procedure that seems fairly simple.You might ask your mechanic if he is acquainted with it. You could probably find an aftermarket service manual at the library and read about it.

 

[pick]

Re: 8o model suzuki 85hp outboard

the motor is a dt85. just put a new set of plugs in today going to see if that helps any. The guy that works on it done a spark check said it was good. It had the wrong plugs in it . the plugs in it and the ones i just put in are no where close to the same. I hope maybe thats some of my problem. Thanks for the help.