Hi NormK I made all the cuts this evening and it's all set for a try in the morning. (Don't want to annoy the neighbors at this hour lol) I was wondering if grinding off the threads on the bolt that goes through the cut-off hole would make it smoother to operate? I haven't tried it yet, so it probably works well anyway, but it was just a thought.
Hi oz, I did try grinding the threads on some of the initial ones I did buy it didn't seem to make much difference. The other thing I do and not sure if it is explained there is i usually grind a bit out of the kill switch ramp. I do this make sure the 3 leg lifter can sit right on the highest point on the cam so that it can fully close the cam. I am talking with my son in NZ to see if he can 3D print off the cams without the low spot on the top of the cam that opens the popper in the start position and if that can be done it will eliminate the need for the washers under the cam, that is an annoying problem that would be good to do away with.
I've done a lot of fiddling with my mod. It's running way too fast with the poppet valve on A, and while idle setting is a bit slower, I can't get the speed to come down any more, even with the screw backed right out. My washers are already at 2mm, any more and I can't get the cam low enough. It is backfiring on shut-down now too. Mmm, I might just have to get another carby...
The replacement part number for the carby is CR03773A, you're looking at about $60. This is also the most recent revision of the carby, redesigned to work with the newest VE series engines, and a replacement for all LM and I believe G4 carbys. They come with a few springs and a couple of jets, along with a replacement guide, specifying which configuration you should use based on your engine.
I had a cup of tea and did some more fiddling. Took a chisel to the ramp so that it slides better over the screw in the kill switch hole. Then cut 1/3 off the spring. A chisel works really well on that plastic and leaves a nice smooth surface, with no burrs.
Getting pretty good control now, but it's revving pretty high on the max throttle. Without stuffing foam into the air cleaner, any thoughts on how to get the revs down a bit? I don't want to melt the piston lol.
^ oztaylz, check the governor diaphragm under that round clip-on cover on the side, check it's not punctured or badly creased and see that it's sitting correctly all around the rim before clipping down the cover again. Also double check that you haven't attached the other end of the vacuum line to the decompressor valve instead of the nipple adjacent to the engine fan.
Ahh, if only victa had kept producing the thumblatch catcher series, they would be in better shape today!
Oz. As long as the ramp is allowing the lifter to reach the highest point on the cam, the only other way to bring the revs at idle down lower is another washer under the cam, I have to do this occasionally , most work ok with the 3 washers I use. The higher you lift the cam the harder it is to get the cable ball entered so I usually only connect the cable on the first notch, if you try getting it into the second notch it bends the cable and creates another issue There is no oil breather, that is the governor that is no longer needed because you are taking control of the revs using the throttle lever. Don't get too concerned about the high revs if you open the throttle too much, this is a Victa 2 stroke, they don't throw rods like all the 4 strokes
OK, all's good now Norm. I added a washer and she's running great now, thank you. Top revs came down a tad and it's idling nicely.
Sorry, I had a brain explosion about the governor!
I sprayed some silicone dry lube into the carby body and on the interfacing parts. It really made a difference to the smooth operation of the throttle.
Hi oz, Glad to hear its working fine, they are an excellent machine when you can control the revs.As for the top revs you shouldn't need to go there much unless you are smashing through very long grass
Excellent thread, much thanks to all and particularly the one and only NormK for it.
I am sure I will sound like a right twit here, but won't be the first (or last) time - but if you have a currently working LM carb, whats the main benefit/s of doing this mod?
I've a very tricky and varied property and use 2 different Victa 2 strokes as part of my regular mow - a self propelled 550 Pro and also a little Mastercut 460 (MSP462) for the very sloped areas and down in the chook run.
Appreciate any feedback on the upside of this mod. :-)
Yeah I only did one as I needed to build one anyway and it certainly works but I found aspects of it tricky like trimming the cam accurately (took too much of one side so bad to even the other two) and fitting the little stop screw in the plastic of the G4 cam (not needed in the LM) Also getting a cam washer combination that was 1.6mm (or whatever it was) thick to raise the cam for a better idle. It worked out well for a first attempt. I'd recommend grinding back the cam humps rather than sawing them off. You can always adopt whichever changes you without the other ones. I agree, if you can cut the grass well and stop the motor, leave it be as long as possible.
Ahh, if only victa had kept producing the thumblatch catcher series, they would be in better shape today!
When needed, I honestly just do the cam mod and cap - I stick with the original kill wires for my own use. Another friend has done the cam mod and just marked the lever at idle. when he wants it off, he puts it in his 'stop' position - which stalls it.
Appreciate all the replies - I did feel silly asking as it seemed like it was of such benefit to do - but much thanks for the quick and clear clarification - I will leave as is. Thank you.
Hi N1KKO, When these carbs work as originally designed they are fine, it seems that once they become problematic that is when the mod seems to sort them out
Thanks for this Here is a link of my mower idling like a dream 3 washers and set the idle. I set my idle once the engine was warm as it will Rev lower and settle. I noticed cold it will just idle above average. I should have had a video of what it sounded like before. Sounded like a cat with some serious anger issues. It would literally bounce up and down and from low to high back and fourth. Now it is super smooth and sounds beautiful. All new seals fitted while I was at it. Good 20mins mowing with no dramas.
I did one to a full crank and it runs very well, although I way over trimmed the cam resulting in a very short movement of the lever (1" or less) for the full range of revs!
Ahh, if only victa had kept producing the thumblatch catcher series, they would be in better shape today!
Cheers! Yer I have noticed that. I took off a little to much. I'm just a quarter out from the top. Not much but. I might experiment and trim back where the bolt hits. Bottom bellow the ramp. Where it hits you should be able to trim that back and it will give you more range because that's all that's stopping it. I got plenty to ply with here so might try that out. I sold this particular mower today. The new owner was blown off his feet. Cold start with 3 pumps of fuel the power torque cranked over like a car engine. Full turn or the key (electric start model!) she was idling like a dream.
Il soon be doing another ground resto on another electric start cammando. That il be keeping for myself.
