Victa mower over revving

[2 stroke absessed]

I have a 1996 Victa 2 stroke with the power torque engine and LM carburettor.I disassembled and cleaned the carby 1 day and now can't stop the engine from over revving.I've checked that I reassembled the carby correctly and it is.I packed up the control spring in the carby with a thin shim washer to slow up the revs and made no difference.I also checked for vacuum leaks:lines to carby(including from control button which is not blocked by the way).O-rings are good(carby to cylinder,starter unit to crankcase and seal above the blade holder).I don't know what else I can check?Can someone help please.

 

[bertsmobile1]

Over reving is only because the governor is not working , their is an air leak or the cam is excessivly worn
Verify the governor by putting some longer tube on the governor spiggot on the diaphragm cap # 15 and sucking on it hard.
By far the most common cause is the diaphragm # 12 getting dislodged when the diaphragm cap # 15 is replaced
The cap # 15 should always be replaced with out the long governor spring # 14 in place to prevent this happening then replace the spring & finally the plug #16 .
I like to put a little rubber grease around the diaphragm to help it stay in place.

Also note the poppet valve # 2 has a cut away and must be replaced with the letter C by the emulsion tube cut out .
You can put up to 5 spacer washers # 9 ( printing error , should have been 8 ) but I have never needed more than 3 and that was on a commercial with around 5000 hours on it .
I have had the odd decompressor fail but you usually can see & hear them when they go west .
Also the diaphragm cap can shrink a little and be very hard to snap fully closed.
Also make sure you have the legs of the Lifter # 10 running in their little slots

The burning question is why did you pull it down.
These carbs will happily run 20 years with no problems whatsoever

To make sure we are all talking about the same bits the numbers above refer to this diagram


And of course how is the head gasket .
Again you can usually hear feel & see a blown one.
Occasionally they make the engine run a bit faster

And by "over reving " what exactly do you mean ?
A bit too fast or like it is about to blow up ?

 

[2 stroke absessed]

Yes bertsmobile 1,we are talking about the same carby.I removed it because the governor doesn't seem to be working.Tall or short grass,the engine doesn't appear to change in revs to counteract the extra load.I have sucked on the governor tube and it's working but as you say intially I found it not working so you do have to be careful fitting that end cap over the diaphram.I/ve made sure each time the poppet valve is correctly positioned with the letter "C" in line,also the lifter is always in place and the carby is in good condition and see no noticable wear in the cam.I also have found the decompressor to be working fine.Early on it felt like the engine could blow up before finishing the mowing,it was revving so high but after fixing the poor fitment of the diaphram it's a little better.I have no reason to question the head gasket.No unusual sound and plenty of power.With a spacer washer in place,I found it to be surging so I removed it.Think I'll just accept it and keep an eye on it.Thanks for your advice.

 

[bertsmobile1]

Did you replace the O ring between the manifold & the engine ?
Sucking on the governor tube should slow the engine & blowing should speed the engine up.
That is my quick & dirty diaphragm test as it takes about 30 seconds to do .
Usually an unresponsive governor is because the diaphragm has gone hard
Double check the arms on the lifter
I have occasionally missed having them in their slots and that causes the engine to run wild .
To test if the crankcase plug is working , run the engine with the throttle low then pull the carb end of the governor tube off and put it in jar of water
It should suck the water up and the faster the engine runs the faster the water should flow through the tube.

There is another O ring inside the starter that is prone to leaking .

However if the engine was not over reving before you pulled the starter off and it is over reving now then the starter O ring is the prime culprit .
They are throw away items & get replaced every time the starter is pulled off .
Being 7" diameter and only 1.5mm thick it is very easy to roll the ring .
Again it gets either rubber grease or silicon spray to make sure it seats properly and is best placed on the starter then the whole lot pushed into the crank case as square as possible .
It is also prudent to clean the deposits off the starter housing before fitting the O ring as a very small amount of build up can cause a leak .
The engine is good for about 6,000 rpm then bang.

 

[2 stroke absessed]

I discovered some new problems.One was the fuel bowl float partly filled with fuel.That would create a rich condition.Also the motor wasn't shutting off.This happened once before(engine shut off is not a great design).Both problems fixed and motor is running close to acceptable speed now.Thanks for your help.

 

[bertsmobile1]

The shut off switch works fine if the rubber boot is replaced at around 10 year intervals and after the engine has stopped the throttle is returned to the wide open position.
Otherwise the rubber boot ends up going hard in the off position.
But no one ever does that
Remember how it worked when it was new ?
Well about $ 20 worth of parts every 10 years will keep it that way. ( $ 30 if the decompressor needs a rebuild )
I love the look on customers faces when they pull the starter and the engine bursts into life on the first pull before the whole rope is out.

When you push the primer cover on it is easy for the float to fall off.
Suppose I have put one on at least 1000 times so doing it without dropping the float off is second nature.
When refitting the cover put a little rubber grease or silicon spray ( NOT WD 40 ) on the new O ring ( old one should never be reused ) then push the cover on with your finger tips around the edge.
When it sort of snaps into place then pop the main jet in and tighten just enough to hold the cover in place.
People try to use the main jet to force the cover into position which makes the cover bend in and also tends to rip the thread out of the body .

Victa made the big mistake of designing an engine that needed almost no maintenance so none ever got done till they would not start at all .