Evenrude 225 tank testing questions

[jurgenscraft]

Hello all,
Why when testing a motor in a test tank with the gearbox in neutral ,the motor runs rough when cold and then improves as it warms up,but does not run as well as it would when under load eg: pushing the boat through the water at 3500/4500rpm.
regards:
William

 

[dono16]

Re: Evenrude 225 tank testing questions

Jgergen, ,, first most all motors no matter what theyre in car , boat , whatever, they will run smoother and better when theyre a lil warmed up... for your problems under load , or on the boat, first is your boat underpowered , ok never mind you said 225!!!!!!!!for the size, is your engine older, the seals and or rings could be bad or getting bad and that would make you loose power. that will loose copresion. ower" Im assuming you have 4 strokes, which is more complex , oil pressure, fuel,,if its EFI ,,i am by no means an expert on an engine like yours but if you narrow your question down give specific examples , model year, model #, from my experience theres some guys that can help ya here,,,,good luck to ya!!

 

[jurgenscraft]

Re: Evenrude 225 tank testing questions

Sorry guys.
it is a Evenrude 225 VRO looper motor two stroke about 12 years old and in good condition recently had it tuned, new plugs etc.... I was wondering why it runs better on the lake than at a idle and maybe up to 2500 rpm in a test tank in neutral. I cannot run the motor in gear it will empty the tank in no time at all, has this something to do with exhaust back preasure and load on the motor, years ago I used to race 125cc watercooled gearbox carts and these two strokes only worked well in their powerbands granted these were highly tuned racing motors working through a 6 speed gear box which allowed the driver to stay in the powerband,I have been told that I need to run the motor at higher rpm on a lake or so, I know this but all I am trying to find out is why the motors run worse in a drum that only supplies cooling water to the motor.Maybe I am asking a stupid question.
Regards. William

 

[Silvertip]

Re: Evenrude 225 tank testing questions

It may be that the carbs were never cleaned and rebuilt on this engine. The low speed circuits in the carb are affected by gum and varnish build up over time so that affects idle and off-idle quality. When the engine transitions to the high speed circuits and it smooths out considerably that's an indication the carbs need attention. A tune up does not generally include carb cleaning and rebuilding unless asked for on the work order. You might try running a fuel system additive like SeaFoam for a couple tanks of fuel. This product (and there are others) can help clean up the carbs. If that doesn't work, its rebuild time.

 

[flabum]

Re: Evenrude 225 tank testing questions

Those engines always run like crap with no load and minimum backpressure on them. As long as it runs well on the boat with a normal load, you have nothing to worry about.

 

[jurgenscraft]

Re: Evenrude 225 tank testing questions

hello all,
Yes the carbs were checked and set up at the service and tune up. I have heard the same story about running bad without load and back pressure, runs okay under load I do not have a test wheel so I run the motor in my home made test tank in neutral for a few moinutes up until running temperature is reached I then stop the motor and drain the carbs, have any of you guys used Wynns fuel system cleaner,they claim that this product will " clean injectors,carburettors,intake valves clean piston tops and rings remove carbon deposits, etc, etc, etc,
sea foam is not available here in South Africa,Wynns is the next best product available...
Kind regards William Wright.

 

[HighTrim]

Re: Evenrude 225 tank testing questions

There is also a product that I use from BRP called Carbon Guard.

It does sound like the slow speed circuit in the carb needs attention. It probably wasnt cleaned properly and is still blocked.