OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Victa Two Stroke Engines G4/LM carby repair/modifications

Hi speedy, glad to hear it works well, problem is now that you have seen how well they work you would never go back to the original design

Yes, I will get my new pt going first then do the mod. I didn't put the kill switch in or the bolts... but the rest works well.
speedy

Thanks heaps for taking the time to complete this mod, photograph it and post it.

1: I will be applying it asap to my twin, which should sort one of it's problems once and for all.
2; Off to the "Green Shed" to see how many G4's I can score (attached to cheap mowers of course!)

On that, most municipalities have a Green Shed where folks donate unwanted/broken stuff.
Always plenty of mowers, some in surprisingly good order. Just got to be quick though because they are usually stored outside and the fuel cap is the first souvenir to be taken.

The next thing that you will find is the float needle, this horrible little part is responsible for the early demise of millions of Victas. The new float needles and primer caps solve this although I have had a couple of issues with them, price on them is an issue if you only want one or two. Do not waste your money buying the ebay ones with the plastic needle they will mess with your head

Hi Norm,
I have a couple of questions for you about your carby mod, if you could offer some answers that would be terrific. I have been thinking about doing this to a spare carb for some time, as I have a couple of machines I use regularly that I think are in overall pretty good shape (seals, viton tipped needle and seat, clear jet, good spark, good compression etc.) which I can never get to start first pull cold. They often start second pull, run perfectly and restart easily hot. I don�t run them out of fuel to stop them but use stabil in the mix. What is the starting procedure with the modded carby? Throttle to run, single prime then start etc? Or are they all different and once you find a procedure that works for that machine go with it? Can I do the cam mod and not do the idle control screw or kill wires portion of the mod? I know I could try this all myself but wondered if you had some ideas already.
Cheers,
John

Hi John, I usually start them on full throttle then back it off but I find they will usually start pretty much anywhere, but full throttle is the spot I prefer as it makes sure there is fuel going straight in. I usually give 2/3 primes. You don't have to do the idle screw, just means that if you pull the throttle back fully the motor will usually stop because it will idle down too low. The idle screw just means you can just crack open the poppet to allow it to idle. This can be played with by only fitting 2 washers under the cam, but this usually keeps the revs too high for my liking, when you are emptying the catcher etc. You can use the existing kill switch but I found them too problematic and this is probably because all the aftermarket kill switch rubbers are not fit for purpose, I was spending way too much time trying to get them to work only to have them play up. The most annoying thing with the whole setup is the lump on the cam that once the lifter goes over the top into the stop position it often becomes impossible for the throttle cable to fight the spring tension and get the lifter to rise back up over the hump. Cutting the hump off gets rid of this problem but then you need to put the washers under the cam to lift it up to the same height as to what was the top of the hump. If Victa had just kept the hump height all the way, none of this would be a problem and the kill switch setup would have probably worked fine. The big problem is the cable has to fight going back up over the hump, fighting the spring and break away from the kill switch rubber which can often jamb all at once.

Thanks Norm, love your work. I think I�ll give it a burl and see how I go, cheers.

I made the cuts on the cam today, easily done with a dremel. I have a couple of G4 idle adjust caps, might try one of those. Just need the washers under the cam and will twist it on and try

Hi jds303,
I should have done it that way instead of using my hacksaw. I still haven't completed one fully, as the machine I was going to try it on has other issues that need fixing first. I should get it done pretty soon.
What grinding head did you use. I have a couple of sets with assorted grinders, but never know which ones to use for a given task.

I've been trying to get my head around this fix for a while now and wondering how best to go about it. I know virtually nothing about Victa mowers. New territory for me! I am going to see if I can fix the old carby as it is before I start attempting any modifications. I have a bad habit of making mistakes that I can never "undo".

The most annoying part with the modification is that if the raised section on the cam had continued right through to the stop position the washers to raise the cam would have not been needed, you could then just cut the ramp to a gentle grade and it would work perfectly. The other issue the washers under the cam cause is because it lifts the cam it makes fitting the cable more difficult and you have to be very careful because you get a slight bend in the cable and then it becomes notchy. Sure if you can get an unmodified carby to work and some do for some reason, just keep it that way but I find I have to modify 98% of them and then I know they will work without problems

Hi Mowerfreak,
I used a plastic cutting disc. A couple of sockets the right size (small enough) in a vice as per Norms instructions, and it makes the cut in one straight drop from the middle of the cut. It was surprisingly easy. Turned out well although yet to try it out.
Cheers,
John

My issue now is I would like to find another 20/30 cams so I have spares to work with because I usually avoid the G4 cam because it can cause me a few issues, mostly with the stop on the cam not having the ramp, so I have to mess about with it to fit a screw in it so I can adjust the stop so the lifter sits on the high point of the cam in the stop position.

I finally fitted my modified cam to one of my mowers today. I left the factory kill wires in place and didn�t modify the cap for adjusting the idle. It just so happens it idles nice and low with the throttle down as low as possible before moving it to the stop position. There is then a decent throttle response up to the run position. I didn�t let it fully warm up to see how it runs when at operating temperature but I was happy with it. I may also change the large poppet retainer over to a small type at some point, I�m not sure if this will affect the speed of throttle response or only the governor response. Overall my one worked well from idle to run, kill wires worked as normal and was a first pull starter with the cam mod and metal needle. I�ve gotta thank Norm for his work on this one and input to the forum in general.

Hi John, glad to hear you are happy with it. The idle screw is not needed if you get the washers under the cam exactly right, but I only seem to get it every 4th or 5th time, just pot luck. The main reason I started removing the built in kill switch was because you get people who want to force the lever back too hard and then the switch would jamb because of the design and then they would try and push it back and the cable couldn't get it to free from the switch. It is a pain fitting another kill switch but at least it comes up against a solid stop so it can't jamb up

Last nights entertainment in front of the telly, another 14 diaphragm caps, no idea how many of those I have made up.

Hi Norm K,
a Victa LM factory on your coffee table. What are other rooms are dedicated to this craft? I hope you don't put them together in the bathtub lol!

MF the rest of the inside of the house is fairly safe, just the outside is fair game, but at least I'm not finding much on ebay and gumtree these days and that makes my wife happy, I think.

Another thing I have been experimenting with on these carbs is the springs in the governor setup. I have cut the big spring in half and put one half on the lifter and the other half on the diaphragm and this seem to work fine. This seems to equalize the pressure on both sides and allows the poppet to move freely. To be honest I was running out of small springs that made me try this mod and the shorter spring under the diaphragm cap reduces the tension on it which is another good thing. Once set up these are the best carby I have ever worked on and I have worked on a few over the years

I finally completed my first NormK special using G4 bits. A lot of fine adjustments and some grinding and searching for the right sizes of bolts and screws were required, but it was a lot more fun and interesting doing it, than I expected.
Well, the moment of truth when I fitted it to this mule and it fired first pull .
It was already dark so I didn't want to annoy people, but it went well the few seconds I ran it.
I think I will stick to LMs if I do any others, as that screw in the G4 cam was quite an ordeal finding the right size to fit!!
But I'm very pleased so far and it was a lot of fun modifying it. Thanks for sharing Norm!!
Does anyone have a suggestion where I can mount the kill button, which is loose at the moment as there is not much clearance under the engine cover on this machine?