Working out the bugs, need some advice! - Rough Idle

[Fletch170]

YO GUYS! PICTURES OF THE BOAT ON THE WATER!!!!!!!!!!!

http://fletch170.blogspot.com/

Launching and trials went off without a hitch! She ran really well. 2 Guys, full of fuel, light chop, she did 42 MPH on the GPS. I'm guessing with just me, light on fuel and trimmed up, she'll do 45-46. Frankly, 42 MPH on that little thing was plenty fast enough.

The only 3 things I need to work out (please feel free to insert opinnions here) is that it has a rough idle, and the lower unit has somewhat of a high pitch hum, almost harmonic sounding, and lastly, I'm not sure if the thermostat is working, as it might be stuck open.

The motor runs awesome 1/3 and up in the throttle, it just feels like it's running on 3 of 4 when idling and low RPM. This only happens when the motor is under load. The throttle response is awesome, and she starts right up.

The sound I'm hearing from the lower end sounds like harmonic vibrations through metal (if that makes sense). It only seems to be happening at certain RPM's.

The temp really never seems to be getting up there. If I recall, on these 2 stroke motors, after a while, the sea water expelled from the motor is usually luke warm when the motor is warmed up. In my case, this never happened, it's basically cool as the bay water. This made me concerned, so I took off the cowl, and after running for 40 minutes, the heads were room temp, and the block was barely "warm" to the touch. Furthermore, after running for some time, she still smoked when coming to a low RPM. This is what is leading me to believe the thermostat is stuck wide open. Thoughts?

[dburr]

YO GUYS! PICTURES OF THE BOAT ON THE WATER!!!!!!!!!!!

http://fletch170.blogspot.com/


The only 3 things I need to work out (please feel free to insert opinnions here) is that it has a rough idle, and the lower unit has somewhat of a high pitch hum, almost harmonic sounding, and lastly, I'm not sure if the thermostat is working, as it might be stuck open.

The motor runs awesome 1/3 and up in the throttle, it just feels like it's running on 3 of 4 when idling and low RPM. This only happens when the motor is under load. The throttle response is awesome, and she starts right up.

The sound I'm hearing from the lower end sounds like harmonic vibrations through metal (if that makes sense). It only seems to be happening at certain RPM's.

The temp really never seems to be getting up there. If I recall, on these 2 stroke motors, after a while, the sea water expelled from the motor is usually luke warm when the motor is warmed up. In my case, this never happened, it's basically cool as the bay water. This made me concerned, so I took off the cowl, and after running for 40 minutes, the heads were room temp, and the block was barely "warm" to the touch. Furthermore, after running for some time, she still smoked when coming to a low RPM. This is what is leading me to believe the thermostat is stuck wide open. Thoughts?

Really pretty!!    

So, you and 2 guys went for a sail?  How ‘bout the Big Boss ?!?  To keep the commissioning coffers in the green and above board, when are you taking her for a sunset cruise? And don’t forget the flowers !!!


Luke warm?... I agree with you Christian, check the t-stat.. The water jacket ought to be warm enough that you don't want to hold your hand on it after you have been running a while.  Better stuck open though then stuck closed...

What are you doing for oil mix now, juz wonderin?  If you are premix, then she's gonna smoke at idle, that's normal..  

Is there any type of resistance/noise when you spin the wheel/prop by hand with the engine out of gear?  Did you do any LU work other than change the water pump impeller?  What does the LU oil look like now and are you sure that it is full?  Is the anti vent plate and skeg on the LU in good shape, no big dings/bends?  If you have a transom mounted 'ducer at the wrong attitude/mounting depth it will make noise and/or throw water everywhere..

If all that checks out then maybe a video with sound and a little more info such as rpm and when is it worst might help diagnose an issue..

For the rough idle, Farley will get you squared away..

If you are bored,  You can start pulling the plug wires, one at a time with the engine at idle to try and isolate the jug that might be misbehaving.  If you don’t have one cylinder firing because of a fuel or ignition issue then the engine will idle no differently if you get lucky and yank the effected plug wire on the first try. I ended up pulling all 4 wires on Zuke 115, one at a time to try and isolate a fuel problem.  I really couldn’t tell what was happening so in a fit of youthful vigor (as I thought of the most famous, yet unprintable, Al Pachino mob quote ever) I pulled all the wires so she ran on #1 only, then put #2 in then yanked #1 and so on till it was time to run only on #4 and then she stopped dead.  I pulled the #4 plug and there was no gas in the cylinder or on the plug, only a sheen of oil.  I pulled that carb and found the idle jet in the carb plugged…

Glad to see she's afloat and sitting pretty!!!

[RickK]

Looks great  :!:  :!:

[love2fish]

looks great on the water! I like the lights in the forward compartments- nice custom touch!

[Fletch170]

Thanks for the complements guys!

Dburr,  my responses are as follows:

So, you and 2 guys went for a sail? How ‘bout the Big Boss  ?!? To keep the commissioning coffers in the green and above board, when are you taking her for a sunset cruise? And don’t forget the flowers  !!!

----Big boss stayed at the dock, as she is 9 months pregnant. Besides, she didn't want to be on the boat if it was going to catch fire and sink.


Luke warm?... I agree with you Christian, check the t-stat.. The water jacket ought to be warm enough that you don't want to hold your hand on it after you have been running a while. Better stuck open though then stuck closed...

---- And I mean, the pee stream was flat out cold, the heads were cold, and the block itself was luke warm, like the console from sitting in the late afternoon sun was warmer.

What are you doing for oil mix now, juz wonderin? If you are premix, then she's gonna smoke at idle, that's normal..

I'm sticking with the factory oil injection. I was doing some research, and I may need to adjust the oil advance linkage rod.

Is there any type of resistance/noise when you spin the wheel/prop by hand with the engine out of gear? Did you do any LU work other than change the water pump impeller? What does the LU oil look like now and are you sure that it is full? Is the anti vent plate and skeg on the LU in good shape, no big dings/bends? If you have a transom mounted 'ducer at the wrong attitude/mounting depth it will make noise and/or throw water everywhere..

-----Impeller was replaced the year I bought the motor, I changed the lower unit oil. Went through the used oil, no water, no metal shavings (Used magnet).

------Funny you mentioned the transducer. I followed the damn directions to a "T" and the sombitch still throws water everywhere. I need to fix that. However, it works great, even at speed.

------I did some research, and the solas props are notorious for making a "ringing" sound at certain RPM's. I can live with it. Chances are, I'm going to destroy the prop in the back sandy bays of New Jersey.

-------The lower unit is in really good shape. No dents, all the grates are there, new Trim Zinc, etc.



If all that checks out then maybe a video with sound and a little more info such as rpm and when is it worst might help diagnose an issue..

For the rough idle, Farley will get you squared away..

If you are bored, You can start pulling the plug wires, one at a time with the engine at idle to try and isolate the jug that might be misbehaving. If you don’t have one cylinder firing because of a fuel or ignition issue then the engine will idle no differently if you get lucky and yank the effected plug wire on the first try. I ended up pulling all 4 wires on Zuke 115, one at a time to try and isolate a fuel problem. I really couldn’t tell what was happening so in a fit of youthful vigor (as I thought of the most famous, yet unprintable, Al Pachino mob quote ever) I pulled all the wires so she ran on #1 only, then put #2 in then yanked #1 and so on till it was time to run only on #4 and then she stopped dead. I pulled the #4 plug and there was no gas in the cylinder or on the plug, only a sheen of oil. I pulled that carb and found the idle jet in the carb plugged…


--------I'm going to try the obvious things first

                       -Replace the Thermostats
                       -Check the plugs for lots of oil, and check the gap, If I'm being honest, I gapped the plugs by "Eye". Need to go  get a cheap gapping tool.


I'm convinced the rough idle is something stupid, maybe because shes not getting up to temp? Bad spark gap? when in neutral, she runs ok (not super smooth, put pretty good). It's when you put it in gear at low RPM's, it feels like its missing or running on  3 of 4. It does NOT cough or sputter. It simply feels like a "miss".