OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Victa Two Stroke Engines Kill Switch on LM Carbs - Design Issues ...

Has anybody come up with a way of making these work reliably. Whoever came up with the design must have been suffering complete brain fade. I'm a little sick of them jambing up on the ramp if the lever is pulled a little too hard and due to the bizare fact the designer put a flat spot on the top of the ramp and then the pin and rubber get stuck and the cable then is stuck. Anybody have a reliable fix, I'm thinking tap the body and screw in a 6mm bolt for the stop (you have to be able to remove the bolt to get the cable in and out of the cam) and then fit a push button kill switch up on the throttle control

I don't have an answer but yes it is a frustrating experience. I would love a workaround if one exists.

I pull them out, fill the whole with hotglue, and don't reef the throttle back too far. To kill the motor, mine usually stop at very low revs or turn the fuel tap off.
Too much mucking about....
speedy

Thanks Tiger, it is such a bizare design that was always going to give trouble, but I guess it was a built in money spinner for the Victa service agents, they must have made more in repairing these that the mowers cost to buy in the first place. I guess if they made the mowers completely reliable they would all have gone broke. Most probably have by now, but that is because of the cheap rubbish coming from China now.

Speedy try explaining that to somebody from the sub continent

Very difficult!

It might be worth trying one of these carbs one day to see how well they adjust to constant load conditions rather than acceleration:

Molkt 28mm carb

LRT, the carby is not the problem, it is quite good as far as carby design goes, once you get the cam profile sorted, it is only the stupid kill switch and the float needles that cause all the problems. On a mower for my grandson, I'm going to try the 6mm bolt in the kill switch hole and just fit an external kill switch, I know this is admitting defeat but I don't have any other answers for this bo bo design, the designer must have been on day release from some institution

I personally hate the throttle cable being in the air snorkel! Horribly fiddly.

The throttle cable inside the snorkel is ok, and being inside it is protected from the elements and very few rust up. I prefer that to the B&S type that are nearly always rusty

I have fitted a short bolt that was near a perfect fit with some fuel resistant silicone left over from the car. Many moons ago I let my ad convince me to wire in a toggle switch and mount it through the sir of the cowl. I usually just turn the fuel off to kill them.

I've done hundreds of these and have never had a problem with them. The key is to use a new rubber every time.
Now if you're referring to the G4 carby which uses the long boot(usually found on the full cranks), well thats another story and yes, they are a right royal pain in the butt.

Hi bigted, is that because on the G4 carby they didn't put the ramp for the kill switch, the rubber just buts up against the square stop

Norm, i'm pretty sure they both have the ramp, its just that when you overshoot the stop position on a G4 it eventually tears the rubber and the wire pushes outwards a little making stopping more and more difficult as time goes by. The newer "stepped" pin on the LM's seems to have eliminated this problem and retrofitting this stop pin to the G4's solves that issue also.

Hi bigted, I haven't been using the G4 cams because all the ones I have don't have the ramp, just a square stop. My problem with this design is it is so hit and miss, they work,they don't work, they jamb, they don't jamb, you just keep your fingers crossed and hope like hell. Pull it back too hard and it jambs and then it is pull the carb apart to release it. Not one of Victas finest moments in design work. I ground the ramp out of one yesterday, fitted a 6mm bolt as a stop and fitted a kill switch on the cowl, works like a kill switch and carby should now

Others and I would love to see pictures of these modifications described.

Sorry Mowerfreak, long gone, my grandson too it yesterday, he was sick to death of the factory kill switch, he just wanted it gone, left a happy man. I ground the ramp out with a small stone in the die grinder, ran a 6mm tap through the kill switch hole, and cut a 6mm bolt 17mm long and it is now a beautiful thing, push button kill switch on the cowl, and he will never be bothered again with that stupid factory setup

Hi bigted, what I have done to the pin that sits in the rubber a number of times is put a slight bend in it so that it points down and by doing this it contacts the ramp earlier and usually that stops the pin from riding up too high on the ramp and getting stuck on the top. Two problems with this idea, first is the pin is hard and can snap, had that happen a few times, and the second is it is pretty much a hit or miss thing, you have to get the pin in the right way so that it faces down and hopefully it will stay there

How does the g3 stop work?

Mowerfreak the G3 is an alloy carby, totally different setup. If you mean the G4, it has just a square stop without the ramp

Ok this is just for Mowerfreak, because he showed some interest in a modification I did to bypass the dumb kill switch. This is one I have just done on a G4 on a full crank motor that after wasting a couple of hours with that insane kill switch setup. This is a G4 cam without the kill switch ramp. With this method I can adjust the cam to stop at the top so that the lifter does not drop off the top of the cam into the lower section when it goes to the stop position. This prevents any sticking/notchiness in the throttle control. My opinion of the designer of this bizare setup is not very high, fantastic motor let down by stupid carby design faults.

NormK, Could back off from the carburetor a little so the picture would be in focus and re-post it.

Thoroughly agree. It's hurtng my eyes to look at it.
Does your camera have macro mode? Most digital cameras do.

Sorry, too late again, it is fitted and now working on a mower as it should. All it is is a 6mm screw through the kill switch hole to use as the stop and a 4mm screw through the stop to prevent the lifter from going over the top of the cam when it comes up against the stop, this way I can adjust the screw to suit the top of the cam. With the LM cam I just grind out the ramp with the die grinder till I get the lifter in the right spot, this is a bit more fiddly. I will do another one and see if I can get a better pic, not sure I can though

This pic shows the adjuster screw fitted in the can so that it can be adjusted so the lifter can stop at the highest point and not drop down. Sorry about the pic they look fine on the camera, but once they are blown up here they get a bit fuzzy and I wanted close ups so you could see what I was doing. They work perfectly and will never jamb up again, with smooth cable operation

Thanks , that looks clever. Pity you can't put up a video, showing first hand how it operates. Maybe if I pull one apart myself, I will fully grasp the concept.

Cheers.

Mowerfreak, I did another one yesterday, got so sick of fighting the dumbest idea in the world, fitted the stop bolt, , dremel out the ramp so the lifter can't drop off the top of the cam in the stop position, this way I don't have to use the adjuster screw by using the LM cam,set the idle screw to exactly where I wanted it, fitted an external kill switch, and I think this is the way I will do them in future, sick of the stupidity of that insane kill switch design. This mower was a typical Victa non starter when the bloke brought it over a couple of days ago and with only the carby modifications it is now a one pull starter and should be a good mower without problems for at least another 20 years. My son is here from NZ so a vid is easily on the cards if somebody wanted to see it. so easy when you know how and it makes these carbys bulletproof. My belief is most of these mowers with G4 LM carbs were all dumped because of carby issues because nobody knew how to fix them. I can do them with my eyes shut, and I can guarantee everyone of them will work.

Mowerfreak, what is it you want a video of the whole modification process of the carby from start to finish, there is quite a few steps involved?

That cam screw and what it does, idle adjustment bolt, and kill switch by pass showing how you seal off the old kill switch portal as well as showing what you do to the kill wires.