OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Victa Two Stroke Engines Power torque poor fuel economy

Hi all

I am in the middle of resurrecting a 80's Mustang GTS (Model #AU067 aka with the Vortex deck) With v40 engine pack the Fuel economy seems to be on the very low side I am wondering at what to look at? I take it that the only real adjustment on the Power torque LM is the poppet valve location. The power seems fine on it with either 1-3 pull cold start.
Now my question is what should the poppet valve setting be for these ones? Should it be set to the Vortex setting which governs at 3250 rpm or is this model supposed to be set to govern at the standard 35-3600 rpm


Thanks in advance


-greg

I have never had great economy from a powertorque, usually 800ml to do my backyard which is of medium size. Unless st pouring smoke everywhere I wouldn't say she is rich...

Greg, is it the mustang GTS with the vortex cover (completly covered) or the Mustang GTS with the vortex base, but open sides cover?

Depending on the power level you are running the engine at, you should expect a simple 2 stroke such the Victa ones to use about twice as much fuel as a 4 stroke of the same rated power output, when mowing lawns. It varies from only using about 25% more fuel at maximum power, to using about 4 times as much fuel at idle. Here is a comparison of 2 and 4 stroke outboard engines (and note that those Suzuki 2 stroke outboards are far more fuel efficient than Victa mower engines):
http://www.outboard-motors-and-boating-geraldton.com/support-files/fuel-efficiency.pdf

Mine has the vortex cover.

Then you will want the lower RPM settings of the vortex, which is designed around quiet operation, if you use the higher settings you risk overheating the engine.

More fuel consumption is a small price to pay for the joy of a 2 stroke.



If you could halve your fuel use and save the difference in about 100 years you would have enough money to buy a new honda.


Yeah sure theres certain times when you would question fuel economoy but i can not see a domestic lawnmower as one of them.
But then most of the time i dont even get the whole shopping about for the best price on fuel. I just pull in and fill the car up. Its easy.

Perhaps I am too used to the Honda GSV 190 and have forgotten what two stroke fuel economy was like.

Ok here is an update.


I discovered that the primer bulb was coming away from its housing and replaced it with a new one and the fuel economy has improved significantly.

Hi guys, new here. But discovered already this thread with an issue I had as well.Will look into this primer bulb thing.
Strange though ,that in my case the fuel economy went significantly poor ever since I put a new spark plug in and gave the decompressor a squirt of WD40 (or I believe that was the decompressor, the UFO-like disk with a few holes and a plunger).

Hi Roler (I've been looking for an opportunity to say that), welcome to Outdoorking.

The primer bulb sounds the most likely cause of high fuel consumption. If it isn't that, you can check whether your decompressor is misbehaving and causing higher fuel consumption just by temporarily removing it, plugging the rubber hose that runs to it, and installing a surplus spark plug in the hole the decompressor comes out of (same thread). If the fuel economy improves without the decompressor, the decompressor is malfunctioning, perhaps by continuing to decompress even when the engine is running.

Why WD40 that???

It is possible that the wd40 has reacted with the rubber diaphragm in the decompressor and it is now not working as it should.

Yeah I read about that 'trick'. So, do I understand correctly, the decompressor should only be active when the engine is being pulled to start? And therefore, the engine will run fine without it, once started (which might be a bit harder than with decomp)?

I was young, ignorant, but enthousiastic and really really keen to make this baby run smooth
The plunger part went a lot smoother though..
The mower starts easy now. Its just the fuel economy being significantly poor. But I'm learning along the way..

Yes Roler, decompressors only operate during starting. I don't suggest that you operate permanently without it, you'd probably wear out your starter pretty quickly, and your starting arm even quicker, but for diagnostic purposes it is a convenient trick. The engine will run exactly the same with no decompressor, or with a good decompressor. If it makes a difference, it's a bad decompressor.

Easy to test.

Remove the decomprssor, suck on where the vacuum line goes on it and it should pull the valve up to close off the hole.




And the other question i have is what are you basing your fuel comsumption on??? They are none to frugal, being a very lowly tuned simplistic engine, the job was the design brief, not fuel economy. Id say it had absolutely nothing to do with the design process as the einge would have been designed well before the fuel price sagas in the early 80's

I'm not sure about what you are trying to say with the above, but:
With the fuel economy I mean it appears my mower, after the cleaning etc, now uses twice as much fuel compared to before to mowe my lawn. The lawn hasnt changed.

And I dont see any obvious fuel leaking from somewhere either.
So, I'm just wondering why the tank 'empties twice as fast' (if this makes things clearer)

If the primer is leaking, it would leak fuel into the engine's intake port, making it run rich. 2 strokes run so badly and stink so much you probably wouldn't notice. If the decompressor diaphragm has dissolved, it would be permanently running on low compression, which would also waste fuel. Hence it seems to make sense to attend to both of those possibilities.

will do so.