OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Victa Two Stroke Engines Over revving and governor?

Ended up buying this Victa mower https://www.outdoorking-forum.com.au/forum/u...amp;Main=8604&Number=49357#Post49357 and after giving the carby a clean, can get it to start but a few seconds it later it revs its head off and even the throttle switch has no effect in slowing it down. Carby is clean, changed the jet o-ring, bottom seal looks ok, any suggestions? I really hate the G3 carby with its governor set-up, this carby has half metal, half plastic set-up.

the throttle doesnt feel right either ? sort of tight and pushes back when you try to slow it ? most times they get bent or full of dirt/dust , its a plastic bowl and an alloy body maybe , the same as the all alloy carb's you dont seem to enjoy mostly . just check the cable easy handles to fold but easy to bend the cable too !

Cable works ok at the start when you try and start the mower but once the revving starts nothing works, you've got to turn the petrol off and wait for it to run out. Will check the cable but doesn't look too bad. I know on Powertorques you've got a few o-rings that can affect the speed but this mower has a different design from what I can see.

no o rings on these 'ol beaut's(except jet) . wd40 it too all over the outside sometimes helps (cable) most times you can feel if its working correctly or watch to see if the outside of cable sort of stretches when using it . disconnect it as a last resort and try working it by hand at the carb' at least then you will know if the cable's working as it should too . i take it the carb is tight on inlet ?

Thanks vcomm, will try the wd40, will also check the tightness of the carby on inlet.

Cables are ok, carby is ok. The problem is that after starting the mower, then you increase the revs, the buttefly valve sticks in the open position and won't move (this is even at the idle position), the cable cannot move the valve back so it just keeps revving high. Can someone please tell me how to set this governor up properly?
What must you do so that both the governor vane and the throttle cable open and close the butterfly valve smoothly and consistently???

is it a white or a black gov' flag ? or metal ! as the back ones are 3mm shorter so they dont foul the cooling cowling . black flags can be used to replace white but not in reverse . could this be the problem maybe ? or the cable might be badly adjusted too , jamming it open then the cable wont return properly

Black vane, cable is ok, alll i need to know is how the top part of the spring attaches to the vane and how much tension it needs to have.

If you back the tension off little bit by little bit the revs may come down privided everything else is correct, each notch in the little thing with the spring on it from memory is supposed to be 100rpm.

Joe, you're right, i think the manual says 150 rpm reduction for every tooth, what i'm not getting is the connection between the throttle arm and the cable, moving the throttle arm is not having any effect on the butterfly valve so i dont have any speed control. How do you hook the governor up so the throttle arm has some control over the speed?

Have fiddled with the governor mechanism and moved the tension applicator 4 notches back so theoretically it should have reduced the rpms by 600, i have noticed no improvement, it still revs enough that your hands shake when you touch the handlebars even when it's suppose to be idling. Have checked the entire machine for air leaks and can't find any so is there anything else i can do to slow down the revs?

Yeah the throttle cable not moving the throttle valve (butterfly) in the carby is normal in the G3 from memory, all the movement is really controlled by the black plastic governor vane. The throttle cable adjusts how much the spring tension is against the governor vane. They revert to full stick/wide open and rely on the governor vane and magneto air pressure (don't ask me if its positive pressure or vacuum, I cant remember) to close it/reduce RPM. Engine slows, throttle open up more, engine revs up vane moves and closes throttle to slow RPM, governs the engine at the set RPM. Could still be too much tension, another thing that can happen is the the bevel tooth drive arrangement that drives the butterfly inside the carby can be damaged. I have also seen the governor vane jammed and or forced behind metal work in the cowling. As far as tension is concerned from memory its stuff all. If there is a fair bit of spring tension against the vane when you move it with your hands the air pressure changes in the cowling caused by the fins and engine rotation have no hope of moving it, a Victa ain't a Boeing 747 (not that much suck or blow)

Another thing to note is that this older version of the engine doesn't have o-rings but has rubber/neoprene oil seals on both ends of the crankshaft to seal the crank case, they are like the o-rings in the respect they need to work.

Have a play with the carby governor first, you should be able to see how it all works fairly easily by looking at it and a bit of guess check and improve, if you have too little tension on it, it probably won't rev much at all, no biggy just add more, whats the worst that could happen?

Good luck!


David

Thanks Dave for explaining how these carbies work. I have tried a few variations on the tension but it doesnt make any real difference to how it runs. Have taken the carby apart again for another thorough clean and now the tickler is no longer trickling.
It points to an air leak but i have no idea where it could be.

Maybe one of those rubber/neoprene oil seals has partially failed allowing an air leak to develop. This would bring on the same symptoms as a failed starter 'O' ring failure in the later model 'Power-Torque'.

Hi there DJ, to check the bottom one it's just a matter of taking the blade plate off, do you know how much i'll need to take off to check the top one or is there a more obvious way?

Hi tiger, I'm not familiar with the early Power-Torques mate, but I'm sure Joe Carroll with chime in here and put you on the right track.

Its not a powertorque at all. You should only need to go aas far as removing the flywheel and cam under it, put a dribble of fuel around the seal and see if it promptly leaks past.

Thanks DJ and Joe, as I remember when I was working on the Mayfair, under the flywheel was the points/condenser setup, does this need to be taken off?

You should be fine to leave the points there, that way the ignition timing and points clearance will remain correct

Thanks Joe, have had a look at the crank seals, no leak there. What i did notice though was that the carby body leaked a small amount of petrol. The g3 carby is made up of 2 halves separated by a gasket. I changed the gasket, lapped the carby, tightened the 2 screws as much as they could go but a small amount of petrol is still getting out which means there is a small gap there, could that be the air leak? I can't tighten the screw anymore, what can you do to make it air tight?