12mph @ WOT DT75

[james skidmore]

I have a 1986 suzuki 2-stroke three cyl outboard i bought recently that has been sitting for 4yrs. the carbs were varnished w/old fuel. i have cleaned them and replaced 1 needle and seat, new impeller pump and fuel lines and filter. out of the middle carb while running,there is fuel coming out of the opening by the choke i think i need a needle and seat for that. at WOT it doesnt seem to want to rev up maybe 10-12mph @ best. i deleted the oil injection and mixing @ 50-1 oil/fuel ratio any suggestions?????

 

[Silvertip]

Re: 12mph @ WOT DT75

Are you sure its running on all three cylinders? Does it have good spark on all cylinders. Appaears your carb job needs some more work. Are you sure you got all the small carb passages squeaky clean. Are the carbs adjusted properly and finally, have you done a compression check.

 

[james skidmore]

Re: 12mph @ WOT DT75

will check the compression havent done that yet. it just runs sluggish under a load. i am going to pull the carbs again and clean them again also replace two needle/seats that i shold have done in the first place. trying to save a buck. this boat is from texas, its a 15ft skeeter. are they at sea level cause im at 5500' would that hinder the boats performance. can i change the jets? there is spark on all three cyls dont know how to check how strong it is though. all three are firing the plugs are black and sort of oily

 

[Silvertip]

Re: 12mph @ WOT DT75

Altitude absolutely affects performance and in your case it appears the engine is very rich (too much fuel/not enough air). But there may be two problems. Make sure the carbs are up to snuff including float level settings and then you need to check with dealers in your area to see what jets should be installed. There is a definite loss of power at altitude so the engine will not perform the same as it did closer to sea level, but jet changes should make it run smooth.

 

[james skidmore]

Re: 12mph @ WOT DT75

the closest suzuki dlr is 4-500 miles away so my parts are mail order and no one will work on suzuki motors around here im teaching myself to work on boat motors

 

[31900]

Re: 12mph @ WOT DT75

Better get a manual.

 

[Steamboat]

Re: 12mph @ WOT DT75

Check with Brown's Point Marine in New Jersey (www.brownspoint.com) for reliable mail order parts and some good advice. They have a parts lookup section of their web page that is very useful. Also do as others suggest and get a manual or two (Clymers and the Suzuki factory one should be a start).

 

[james skidmore]

Re: 12mph @ WOT DT75

thanx for the info will be ordering parts on payday. will keep you updated on my progress. THIS IS AN EXCELLECT SITE FOR THE NOVICE BOATER AND THANX TO ALL WHO REPLY TO THE NUMEROUS QUESTIONS!!!!

 

[jim dozier]

Re: 12mph @ WOT DT75

Squirt some gas into each carb 1 at a time while its running. If it picks up you know its lean. The Mikuni carbs on that engine must be very clean. Just an aside the Suzuki oil injection is very reliable if the hoses and tank are maintained. Added benefit with oil injection, the engine still gets oil if the carb is clogged which may be your case. Don't run it for long until you get the carbs cleaned or you will be rebuilding it. As said above verify that you are running on all cylinders. If you have lost one either due to ignition or fuel it would probably only do about 12mph.

 

[james skidmore]

Re: 12mph @ WOT DT75

just to let you know my first carb cleaning job was far from complete. my jets on the outside of the carb were clogged. the emulsion tube that slides on to the tube that runs verticle in the mouth of the carb was plugged. so now im taking my time and doing it right. i ordered two new needle/seats. the high speed jet is a 140 i might have to increase the size for the elevation. ill let you know. thanx!!

 

[andy6374]

Re: 12mph @ WOT DT75

You will want to decrease the size of the main jet at higher elevations due to the decrease in the ambient atmospheric pressure. If it is idling rough, you may want to increase you idle jets. <br /><br />Idle jets --> air jets<br />Main jets --> fuel jets<br /><br />Someone please correct me if I am wrong. I know this is true for merc. carbs., but I'm not sure for suzuki but I assume the design is of the same general beast.

 

[james skidmore]

Re: 12mph @ WOT DT75

Originally posted by andy6374:<br /> You will want to decrease the size of the main jet at higher elevations due to the decrease in the ambient atmospheric pressure. If it is idling rough, you may want to increase you idle jets. <br /><br />Idle jets --> air jets<br />Main jets --> fuel jets<br /><br />Someone please correct me if I am wrong. I know this is true for merc. carbs., but I'm not sure for suzuki but I assume the design is of the same general beast.

 

[james skidmore]

Re: 12mph @ WOT DT75

the people i bought the boat from said they had it running on navajo lake pulling a skiier behind it so im thinking it has to be dirty fuel system. i have two more needle and seats coming along with a fuel pump rebuild kit we'll see how that does!!

 

[james skidmore]

Re: 12mph @ WOT DT75

i just did a compression test and i have 110-120lbs of pressure on three cylinders. the carburator kits are not here yet but im hoping today they will show up. will keep you all posted!!