OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Victa Two Stroke Engines Victa Matercut 460 utility powetorque power loss

Hi folks,

This victa has maybe 25 hours on it. It loses power at full throttle, then almost stops whilst cutting, then reponds to choke. It has a yellow spring on the diaphram. The diaphram cap seems to be restricted.

It has a yellow poppet valve with A and C marked, and the number 4. This poppet valve is not continuous?

I put a long grommet into the carb for the cut off switch for a possible repair, maybe did not shorten it enough. The original seemed damaged.

Seems to be some damage on the intake manifold O ring, but after removing it, same goes for the starter housing.

Bore, piston ports, decompressor, seem excellent

Plug looks good

Bore not marked, piston moves freely.

Fuel supply, fuel pin, float all seem ok.


The mower would run at full throttle and work, and stop working, then go back to normal again now and then.

Hey guys

Any Ideas for a dramatic loss of power whilst cutting?

Taa

See ya

Hey I changed all the O rings, but also put an old poppet valve in, a white one and set it to A. The mower seems to cut well under load now, but revs maybe high?

I removed the retainer on the diaphram, could this increase RPM?

What sort of engine response would come from a damaged intake manifold O ring?

This machine has a new type plug with an inbuilt resistor. Does anyone know about these plugs failing?

Cheers

Unless the diaphragm retainer is causing an issue itself, I tend to keep them in, or more often, replace them with a small flat clip (Like the one used in the G4 carby)

By memory, A is not the normal setting, I believe your mower should be "C" for the poppet valve.

An air leak on either of the intake seals, or the starter seal, will case the fuel mix to lean out, and this will in turn lead to severe over revving. If you dry out your carburettor when turning the mower off (By turning the fuel tap off and letting the mower "run-Dry" you would recognise the quick rev increase just as it dies, this is the mix leaning out, a leaky seal would mean severe excessive revs, and little control on the throttle, as well as often being harder to stop.

Its probably not a good idea to change multiple things at once.

The plug should be a CJ8 or an NGK BM6A. I personally preffer the latter.



If it is revving too high it is most likely sucking air in somewhere.
The Oring the carb goes on is the least likely to leak, its usually pretty oil soaked which would help seal. Its a common size, easy to replace.
The other oring where the inlet goes in the block is prone to leaking, of the top of my head these are an 015 size.

The starter O-ring is not an imperial size, imperial ones are either to fat or to thin. Its a metric size, cant remember if its 98 or 95mm. They are not cheap even in bulk from a bearing place so its worth just picking one up from a mower shop.

Is the Diaphragm in the carb seated propperly. This is a very common spot for an air leak. If its not seated/sealed right the motor will rev.



Removing the plate will effect the govenor.
The spinning flywheel crates suction at the vane on the block, that pulls on the diaphragm pulling the poppet back in, if the revs drop, less suction lets the poppet out. If you soften the diahragm and let it flex more allowing the poppet to move out.