OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Victa Two Stroke Engines Victa G4 carburettor - Governor Springs

Victa parts diagram (attached), lists 5- possible return springs.
I've lost the original and have no idea on which one select.
- Can someone on the forum recommend starting point and the significance of the 5-very different possible spring loads? .

- Bumps

I take it your not talking about the highlighted section as that referring to the kill switch set up.Now what the spring section (14A,B,C,D and E) is referring to,basically is about the spring in the diagram marked as 14.Different model mowers had different tensions of springs. Now where it has the colour ie. Green clear yellow etc is referring to the colour that the spring had painted on it.
So I'm not sure that there was a real lot of different's between the different coloured spring tensions.As I've found that spring manly is there to push on the diaphragm to allow the engine to have some kind of idle.
Now you've set the topic as G4 as far as I knew G4's had the same spring as due to an idler screw knob on the outside of the carby you could adjust the idle by turning that.
So (and I could be wrong) this is more referring to an LM carby.
I guess the question is what size engine is the carby for?
Maybe someone with a little more expertise can work out which one is required.As I'm better with the G4 specs not some much the LM. Not that there was a lot of difference.I guess Bigted would certainly be better with that.
I hope that helps a little bit.

G'day Bumps,

The standard outer spring for most 160cc engines [both full crank and PowerTorque] on mowers is the CRO3417A. But it would help to pin it down, if you could post the model number, or some pics of the mower.

This spring sets the governed speed of the engine, and each 50g increment in spring constant will increase the speed by 100-150rpm. You really need a tachometer of some sort to check this.

There's a collection of Victa Service Bulletins on the G4 in this past thread: https://www.outdoorking-forum.com.au/forum/ubbthreads.php?ubb=showflat&Number=38908

See also the Service Manual G4 excerpt in Section 4 HERE

Thx Blumbly + Gadge for the above advise and I now think I've worked it but just for the record, the engine I'm working on is a 160 cc full crank engine having points ignition. The carburetta has the knurlled idle speed adjuster knob but I am missing the large spring .... Its gone and I'm bugge#ed if I can find it hence the request for assistance in finding the correct one.

The conclusions that I've drawn from your advice is as follows but please correct me if you think I've speared off in the wrong direction:

1. If the carburetta has the knurnelled idle speed adjuster then one should use the 150 gm red spring (CRO3417A). The spring working tension can be altered by turning the knob in and out to obtain the optimal idle speed and top end speed...... seems to make sense!

2. If the carburetta is the later model one without the idle speed adjustment knob then its a bit of trial and error using the different available springs. If this conclusion is correct then one would have to purchase all 5-springs (and probably 5-cans of VB to assist in keeping the patience) and do the trial error experiment by sequentially replacing the springs on the operating engine and seeing how it goes)..... Again, seems to make sense but why would the highly skilled Victa engineers replace a simple knurlled knob speed adjuster with some thing as laborious as a trial and error spring replacement procedure???

I am however a little unsure as to what affect the installation of brass washer(s) under the throttle valve assembly would have on top end speed and whether in fact the trial and error spring substitution negates the installation of the brass washer that was offered as a means to reduce idle speed?

One last query, prior to pulling down the engine, it was really smoky. I ran the engine with new fuel and 25:1 2-stroke oil. I'd fitted new needle in the carburetta so I'm sure it wasn't flooding and I'd fitted a new air cleaner to ensure that there wasn't an air flow restriction. - Gentlemen, in your highly learned opinion, can the different available large spring tension or faulty small spring (the one that fits under the diaphragm) alter the air/fuel ratio to cause a rich mixture to the engine and hence the smoke?

Thx - Bumps

If springs are not working correctly I can't see why it would blow smoke,as I'm guessing the smoke will be a blueish in colour which would signify oil is being burnt.
Now I know you said it is a full crank 160cc.
What is the engine off?
Do you know how old it is?
If you don't know post the engine number up and I'll see if I can get some more info on it.You have me curious now.
Also with the smoke.
Do you know if it has been sitting for long?
How long did it smoke for?
Was it thick smoke?
If you could try and post some pictures.A picture is worth a thousand word.

G'day Bumps,
The carby adjustment knob only affects the idle speed setting. The governed speed adjustment is the governor vacuum tube connector [Victa: vacuum control button] on the cowl - it is rotated to adjust the speed.

Victa's recommended governed speed range is pretty broad anyway; 3500-3800 rpm for catcher models; 3500-4200 for non-catcher.

For the G4 carby only, note the jet/tube installation instructions in the Service Bulletins - these carbies will run rich if the tube is bottomed in the jet, before it's screwed in. The springs don't influence the mixture.

Dear Blumbly and Gadge,

I had a good look at the service bulletins kindly provided by Gadge and I think that I have incorrectly labelled the Carby as a G4. I'm mow confident that it is indeed an L.M. (I was of the belief that the idle speed knob inferred that it was G4 but this doesn't seem to be the case).
With regard to the smoking questions:
Do you know if it has been sitting for long? ..... It smoked on start despite clean new fuel, clean fuel tank and clean carby
How long did it smoke for? ....................... From start right through rev range for 10 min - It used a heap of fuel!
Was it thick smoke? ............................... Heavy blue smoke that resembled flooded engine but it ran well and had new needle.

I have a hunch that the rich mixture is causing the extreme fuel consumption and heavy smoke. As per service bulletins I still need to check that the seat is brass. I must admit that I am a little puzzled with the purpose of the G4 spray tube and the LM filler tube and whether these can by-pass and allow fuel to run directly into the carburetta throat and upset the correct air fuel ratio?

I'll get the replacement red spring that I originally asked about and put another needle in it and try it again on the coming weekend. It's starting to fine up in Melbourne, the grass is growing, final football is rapidly approaching so I know she'll be growling if I can't mow the lawns so I've got to get the bastar#d going.

I'll let you know how I fair and send some photos.

Cheers - Bumps

Hi Bumps I'm just a bit concerned with the colour of your smoke.I mean if it appears to be blue then that is oil burning.A mixture problem would be more of a black smoke.A two stroke can run with worn out rings it will just burn the oil a lot more and the fuel will pass though the rings going into the upper cylinder.If it's not to bad it still could be a sing of wearing rings.Using a lot of fuel is also a sing of ring problems.I just don't want you to go through all the trouble of finding a spring only to still have the blue smoke.See if you can see through the muffler port you might be able to see how the rings look.

Thanks Blumbly but I had the cylinder honed and fitted new rings, bearings and seals when I had it down. The cylinder was a bit scored but the professional hone brought it up pretty good. The engine re-manufacturer who I used was an old experienced chap and he was happy with the job. Having said that, I never actually mic'd the bore to check for wear. The massive increase in fuel consumption lead me to think that the carby may be flooding despite the new needle that I installed?

Bumps I have one with an LM carb fitted and that choofs out heaps of smoke, the bore I suspect has nothing to do with your smoking problem

Yeah thanks Norm,

A second new needle sorted out the excess fuel consumption and the smoking.
I guess this is what happens with imported plastic / fantastic needles from China (or from where ever they're made?

The rpm is still up and own like the proverbial whores draws so I still have some issues with the mongrel. It now idles beautifully when the throttle is set in the stop position (electrical cut out switch disconnected) but the engine stops when the throttle is slowly moved to the start position. If I move the throttle rapidly through the start position so that it doesn't stop, the engine roars into life at full rpm but then the speed becomes erratic when the throttle is moved into any position between 3/4 throttle and start position.
... I've just about ran out of ideas on how to fix it - I've tried different cams, different springs, different main jets, different pipette valves and its positioning in the body relative to the fuel spray hole ...... I noticed the newer popettes have the letter A,C, O and a dot inscribed on the under side and that the moulding has ports moulded into them that blank off the fuel spray hole in the carby body when the pipette is set in a particular orientation. Through trial and error I've noticed that the engine runs best when the pipette is positioned with the letter "C" is aligned with the fuel spray hole. I think I now have one seriously screwed up carby and apart from purchasing a new one, I'm unsure what to do next.

- Bumps

Sorry Bumps I have a couple of them that react that way, I fixed them by pushing them to the corner of the shed and now I just ignore them When I find a mower with a Briggs and Stratton with a rusted out base, and that seems the way a lot of them, I will just swap the motor over and probably just dump the Victa motors

Bumps yes the correct position of the poppet value is in the C position.
If your having revving issues (and is sounds like there's been lots of work on the carby)check your decompression valve.Pull it out it should be in the open position.You can suck on the pipe which should close the valve.I have had problems with them in the passed and it gave me the same problem you have.Although it did also allow the engine to over rev as well.Certainly no harm in checking.After-all it's only a 3/4 spanner only takes five minutes.

Thanks Blumbly but I've already done as you suggested. The valve was open and it closed when I sucked on it.
I even swapped it over with one that was on an operating engine but it made no difference.

Over the years, it would appear that Victa mucked around with the design of the internals on the G$ / Lm carburetta.
I now have 4-carburettas stripped down and there are subtle differences in the design of the internals.
One interesting observation was the change in the length to the vane on the cam. I have two cams with long vanes and two cams with significantly shorter vanes. I'd post a picture if I had one but I'm sure you understand to what I'm referring?
The poppette design has also changed - I have two with no profile under the sealing lip and two with porting under the lip.
I cannot detect any change to the designs of the lifter?? With regard to the body design, I have one that has small nozzle attached to the fuel spray hole .... I guess it was done to improve air / fuel mixing in the carby throat and three carbys without the internal nozzle on the spray hole.

So as I said in my earlier post, I think I've mixed up a number of parts from different models but its also clear that Victa had issues with the carby from day 1 otherwise they wouldn't have stuffed around with the design. This view seems to be supported by NormK's above post.

Still not sure which way to turn except by purchasing an entire new complete carby but it goes against the grain if get my drift .... hate being beaten by a lump of plastic!!

Regards - Bumps

Yes the cams were changed, the earlier/shorter vane ones require the use of the long cut out plug. The poppets are essentially the same but there is a break in the 2 profiles a and c unlike the earlier poppet valves. no change in lifters apart from colour that i know of. bodies were changed yes hard to explain earlier vs later without a picture.

Do not use any non genuine parts in the carbys especially primer caps, needles, diaphragms, and even cut out plugs. They do not always work correctly or last like genuine parts. Poor man pays twice.

Dan, how would you identify non genuine parts these days and where would you get them and from what I have seen on ebay, the parts are not cheap, so it makes these motors only tip material. They will never be collectible in any shape or form, so in my opinion it is not worth spending any money on them. I could be wrong

this was from another post on the G4/LM

Genuine parts have the victa part numbers on them. Genuine needles are orange, whereas non genuine are yellow or black. Yes a brand new primer cap is about 20 bux, a diaphragm is about 15, same price you could pick up another mower for. The funny thing is ppl spend money on a new primer cap and oring, fit a new needle, new spark plug and air filter and it still won't run so they sell it. As it would turn out in a lot of cases the jet simply needed to be unblocked.

Some are worth money, i have plenty of spare bits which helps but occasionally you will have to buy something brand new ie orings.

There is always heaps of these 2 stroke Victas out there not running and worth nothing and in nearly every case it is as a result of a bad carby. Victa did very well to trash their name by fitting these to an iconic brand. I guess Merv had been moved on by this stage?

G'day Norm,
There's another reason for there being a predominance of Victas with stuffed G4/LM carbies. It's just sheer weight of numbers!

If we look at Victa's 2-stroke governed carbies only, the G2 was only used in 1968-9 [and maybe 1970], and the G3 from 1970 to 1975. The G4/LM series first came out in 1975, so it has been current for over 40 years now...