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

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?

Full cranks are dead easy to fit the kill switch, I use a round one that fits in the existing hole in the steel cover above the carby and the earth wire from the switch I just put on the steel cover with a pop rivet. It is good when they start so easily and come back to idle and not revving the guts out of it and a nice tickover at idle when you go to empty the catcher. The G4 cam is a bit of a pain because of it not having the kill switch ramp. One thing you have to be careful of is to not pull back on the throttle too hard because you can pull the cable out of the cam and this splits the cam.I am putting a stop in the air filter housing to stop this happening.The six mowers I got a couple of days ago all rev way too high so I have to modify all of those to get good throttle control

You must have it down to a routine NK, but it was quite a learning curve for me ( though nowhere near like you, who had to come up with it). My next one will be much easier and better than this one.
Regards the kill button placement, I was considering that hole only to remember it's for the vacuum tube from the decomp valve. So you just blank it of at both ends and not bother with it?

MF you still need the decomp hose hole, the other hole is further forward. I usually don't run the decomp hose through the cover because it is too messy, trying to get it connected up and hoping it doesn't come off while you struggle to get the cover into place.Sometimes I have cut a slot up to the hole so the hose can be put in place and then the cover can go straight over the top. It is easy to see why Victa wanted to design the Powertorque because just fitting this in a production situation is just too time consuming, this part of the production line would have been a bottleneck. As you can see in this pic the hose is run up inside the cover and the governor fitting has just been removed

I soldered the wires on only to have a d'oh!! moment when I wanted to fit a bracket and realised I could no longer fit the nut and washer or put it though a hole.
My soldering skills aren't exactly above par, so I used a zip tie to mount it vertically to avoid having to de-solder and attempt to re-solder such intricate electrodes again. I quite like this solution as it lets the wires hang in their natural state and looks quite tidy for what it is.

MF, why would you put the carby on facing that way, you can't get at the primer cap and with them around that way the snorkel sticks out too wide and gets caught on everything. I hope that is not a latching switch, because you will get caught out not knowing if it is on or off, I use the momentary ones where when you let it go it is ready to start again.

Don't worry, it's a spring one you have to hold down to "turn on" the kill.
Unfortunately it has to face that way because it's on a . VC-160 frame which doesn't allow enough clearance for a right hand snorkel to fit between the frame and the fuel tank. I wanted to use the opportunity to try your carby mod on a charity case like this Franken-mower I found, and I don't have the original left hand snorkel for this configuration, so made do with stuff I had lying about. Yes it sticks out too much but it stays in place and I'll replace it down the track + watch extra carefully where I'm going! This project was mainly to learn.

OK you're forgiven. I picked up another Powertorque today from Gumtree and the bloke told me he couldn't get it started. When I got home it was obvious why, the primer cap was upsidedown, but at least it had a full tank of fresh fuel in it, runs fine but as usual needs the carby mod done

I gave Frankenmower a longer test today and it took only four pulls with the throttle moved up to medium to start, without pushing the hard to reach primer. I think I will fit a G4 grey primer-less cap to this one if it keeps starting this well from cold, and save the white cap for when it can be more useful.
It went well but I'll have to watch more carefully how I trim the cam next time, as I definitely shaved to much off. I had to file away a bit of the bottom of one of the spider legs to clear the screw on the cam as it rotated and lifted the spider up!
I'm grateful it goes despite that, but the result is most of the throttle rise occurs only in the first quarter of the t bar movement and the rest of the way, it rises just a little bit more to max revs.

MF what you can do with the G4 cam is you can adjust it so that when the cam is up against the stop/bolt the 3 leg lifter is sitting on the highest points on the cam. You can get this exactly in the right spot by adjusting the screw in and out

I did that as best I could and carefully observed each leg of the three prong lifter. Problem is that I cut too much off one of the ramps on the cam, so I had a situation where the legs on the other two were starting to lower again, but the third leg still hadn't reached its peak, so I had to have a compromise. Also, I didn't have much thread protruding by the time I adjusted the G4 cam screw.
I'm quite happy with the result anyway. I'll do a better job next time.

I made up 14 of those primer caps a month ago, and I just used the last one, no wonder I'm going through needles like there is no tomorrow.

That's a good indicator of how many you are moving!

That is 40 days since I made them up, there is still a few waiting to be sold so it probably works out to one going every 5 days but on average it takes me at least 2 days to get them repaired and sorted properly so it works out about right

Did a carby on a full crank this morning and it still wants to rev like crazy and I can't see any reason for it, I'm guessing it has to be something wrong with the carb body

Changed the body and used the same internals and it works fine, now I have to set the problematic body up with another set of internals to prove if the body was the problem

You may have made a blunder in assembly, but may be a hairline crack in the body?

Had it apart a couple of times couldn't see anything wrong, I will put it on a PT sidethrow slasher that belongs to a mate and see how it goes. I told him last night that I want it gone because I have had a number of people here asking if it was for sale. I have one here with a full crank but the base is rusted out and they are getting a bit scarce on the ground now
I had a bloke come and get a PT a couple of days ago and he brought his old PT for me to look at. He bought it new 25 years ago and it had only had new blades fitted a number of times, but sadly I think it will end in the dead motor pile

Ok MF, I fitted the carby to the sidethrow and it behaved erratically, didn't rev hard like it did on the other motor but had to keep opening and closing the throttle to keep it running. Changed all the internals to another body and it works perfectly. This is only the second body I have come across that had a problem and just would not work, apart from the obviously damaged/broken ones.
Will my mate appreciate the effort I put into it? probably not but he will say thanks because he always does. Not only that he would have to be the only contractor running around with the oldest collection of old Victas mowing lawns in the inner leafy suburbs of Melbourne. And he is still pressuring me to fix an old full crank 550 self propelled I have here for him. He says the looks he gets from other contractors is priceless

Only a billion or so more out there. No great crisis. It was interesting to find out though.
It is indeed unusual to see Victa two strokes being used by mowing contractors/ runs.
I'd be a bit concerned about the fumes day in day out, but I don't imagine four strokes have catalytic converters either.
Councils used high output powertorques for years in their commercial grade equipment.

Thought I would add this in here, I dodgily added a missile style switch and cover (had to reverse the contacts to the body) up to the air filter housing with some flexible round black speaker cable, and crimped on some spade terminals to the existing kill wires since the long terminal snapped off from the wire. I will crimp some spades on to some lengths of wire with the victa kill pins on the other end so I can install them in to the carb before it is refitted, then plug the wires in to the other ends when the carb is back in place. Should eliminate fiddling with the kill wires if and when they ever go back in. I used a champion brand 10mm vacuum cap to go over the spigot in the carb body, all works well. I had to give the body and jet a good run in he ultrasonic cleaned as I was having starting problems again. Starts first easy pull now. I may try and insulate the back end of the switch a bit better, mount it to a bracket and run the wires in the snorkel if I get really bored at some point.