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

Hey I know how they work.

If you have a box of bits, thats nice, the bits belong in a box.

Fix lots and lots and lots of Victas and eventually you'll get enough cooked ones that you can just grab another carb and snorkel from the spot where they hang on the wall and fit that and see if it works better.
Some do, some are shyte. Carbs off cooked motors tell you one thing, it sorta ran once upon a time. I personally like the ones that are full of grass, that means it ran like a total gem until it inhaled enough to kill itself.

One or two parts. Maybe a diaphragm cap and spring out of the parts box, any more than that and your chances of it doing what it should go down hill quick.

All the different length throttle cables are pain too.



Try re roping a starter on the motor when some fool has spun it too far the wrong way and the inner hook has jumped off.




Wheres this shire master?? Im needing some bits.

Cheers.

I'm hearing you Rob, wish you were on this side of Melb so we could have a burning of LM carbs, G4's seem a bit hard to find. I'm not totally the carb is the problem, I'm leaning towards the problem being inside the crank case

Hi Norm,
First of all a big thanks for helping me get the bast#ard to work.
Apologies for not getting back to you earlier but i've been interstate on work.
To answer one of your queries, all we did with your smokin carby was bolt it on to my engine. It started and ran well and didn't smoke at all. It idled quite quickly but we had control from fast idle to run speed. I think I suggest that we may have dislodged dirt from under the seat and this prevented the potential slow flood that you may have been experiencing? Again, the plastic needles are very agricultural..... I had to buy three of three of them before I got one that seated off properly on high float level.... not really an issue at $1.00 each but incredibly annoying!!
I'm just about to install the kill switch wiring and mow the grass that is now ankle high. I'll let you know how the bast#ard goes..... Guess I'll just go have to quickly move the throttle level through the dead spot to stop the engine from cutting out.

These plastic carbies really are a pain in the Arse. I guess this is where Victa made money but also pissed off a lot of people ..... $160 for a new one is absolutely absurd!! I think I just keep hunting around for an old Amal 361 ..... at least they are reliable!

Give me a call (0401 143922)if you want me to bring over my "working carby" and we'll have a play with "old smoky" and have a milkshake as well.

- Bumps

Bumps no problems, not sure how many of those carbs I have and they all have different characteristics on that motor. I put a different carb on old smokey the other day and cut a big area in Mckinnon where the grass was over a foot high and it handled it reasonably well but this [Censored] no throttle control gets up my nose. I ended up with another Powertorque a couple of days ago a Chinese one, and it runs ok but still has this no throttle control issue. I'm looking at making an fitting up so I can fit one of the Villiers carbs I have here to see if I can get that to work, might try the same on yours. Only problem if you come over to my place it is a bit crowded at the moment in my shed, I think 28 mowers,1 Torana, 3 motorbikes,4 ride on mowers, several red Holden motors and mountains of other good stuff.And that is just the stuff in the main shed.I guess you now know why I can't put my fingers on that Amal.Lucky for me I sold 10 mowers in the last couple of weeks, otherwise it just won't fit. Best I give you a ring in the morning

Bumps, you are dead right, $160 is absurd for a just a new carby when you can buy a complete, brand new 6hp motor in a box for exactly the same money and boy will that cut your grass. Openwarehouse in Dandenong has new in the box motors for $140

Norm when the carbs are set up right and there are no vac leaks or other engine related issues they are great. All of my older power torques and full cranks will idle at just above stall speed and and run at any rpm upto 3200-3400rpm governed rpm. Why would buy a new carby? The most expensive part you will ever need is the primer cap around $20

We are all ears Dan, any advice you can give will be much appreciated, I don't believe it is a carby problem because we can completely control the revs up and down through the rev range by sucking and blowing through the governor tube which proves the diaphragm is working ok and lifting and lowering the poppet. I was listening to a neighbour across the road mowing his lawn with one and it was revving its heart out and I wasn't going over to offer him any advice because I have none in this case. They obviously work ok or they don't

See my last post in the other thread 'over revving power torque'. Yeah most owners will just keep using the thing whether its revving its tits off or chugging away still on choke, they'll only give up once it stops dead lol

Gidday all,
Happy to report that with invaluable assistance from Norm K, we managed to crack the code on these mongrel Victa plastic fantastic carbies and I now have a sweet running machine that idles beautifully at around 600 -750 rpm and runs evenly out to full speed 3,500 rpm over the full throttle movement and can be set to run at any speed between idle and max.

There is no doubt in my mind that the Obsolescence Engineers at Victa played a big part in making the engine run at max speed 3,500 rpm so that it would unnecessarily wear out. Its is also abundantly clear to me that Victa had problems with this plastic carby from day one otherwise there would not have been four (4) different versions of bodies, cams, lifters, lids, lower spring, upper spring and diaphragms. Each item had the same main part number but there as a small suffix labelled 1,2, 3 or 4 moulded just above the main part number. Further, all the parts are interchangeable but the differences are incredibly subtle. I think that there is a big problem with spare parts as only the latest part is available and that putting the part into a carby that was not specifically designed for it causes the issues that I've encountered. The obvious solution to rectifying a bad carby is therefore to purchase an entire new one but at $160, its a complete and total rip-off.

Just to re-visit my problems:
1. The engine smoked badly on start
2. The engine would either rev its balls out at idle or stall at zero rpm depending upon the parts mix.
3. There was no throttle control - it was full speed or no speed.
4. The throttle lever was sticky and jerky and regularly jammed.

Smoking issue was fixed by changing the needle to stop flooding. Several needles were needed in the trial and error procedure. And yes, I was careful to ensure that the pointy end was positioned against the seat and that there were no issues with the float. It was simply a fact that the manufacturing tolerances were high variable and factory QA none existent and this very important mass produced item.

I finished up purchasing two new springs to ensure that I had a matched pair and it was impossible to know from the assortment that I had which were the correct ones as all colour markings had vanished.

Norm K in a fit of sheer brilliance decided that we should reshape the cam angle, remove all sharp edges that were causing the lifter to bind - See photo. The reshaped cam made all the difference and enabled full smooth throttle control so that the engine could be easily set to run anywhere between 750 rpm and 3,500 rpm.

We found that a poppette height variation at idle of only 0.004 inches would change idle speed by 1,500 rpm. We initially tried to make final idle adjustment using shim washers (7 mm dia) under the cam (as per Victa information sheet) but did not adequately give us the idle we wanted. In desperation, we fitted an old cap - the one that used a knurled knob for idle speed adjustment and it proved to be a godsend (see photo). The spigot contacts the top of the poppette and allows "micrometer" adjustment of the seat appature at idle and gave us the means to set idle at 600 - 750 rpm .... the engine ran smoothly and quietly at this slow idle speed and we at a loss to understand why Victa discontinued the carby lid design that had the facility to adjust idle speed???

Anyway, job done , grass has been mowed and the mower has been successfully started and run from cold a total of 6- times to ensure that our mods worked. Starts first time runs beautifully at any selected speed
..... Thx Norm K - brilliant idea to reshape the cam and great execution!.... Photos attached - I hope that they come out.






- BUMPS

PS:
1. That's Norm K in the above photo.
2. I manufactured the red steel fuel drum (gusseted to the steel cowl)because plastic fantastic original fuel tank split at the seams.
3. What a great result on Saturday - Go Doggies! Incidently, same day as I got the mower going properly after 6 -months of stuffing around - I had a premonition that the Dogs were gunna murder those Swanny wooses from Sydney!

- Bumps

Bumps, it was a joint effort driven by your refusal to accept the way these carbs work or why they work so badly.I have a few more up and running well, still a couple of disbelievers out there but who cares about them, we know what works and that is all that matters to us. What I would still like to try is one of those new black poppets you bought to see what that does.All the poppets I have are the white original ones and I have set them all on the "C" mark. I am convinced you can mix all the parts up, I sure have, all the bits from half a dozen carbs were in the one bucket, and it doesn't seem to matter. The material the components are made of is pretty durable and I have not been able to determine that any component has any wear on them to cause all the problems these carbys are prone to. Congrats on the Doggies win, was a great match to watch


The pic shows the thumb screw adjuster I fitted to them, works well

Hi Norm K,

Give me a call on the weekend (Sat or Sunday) and I'll bring the a couple of the plain black poppettes over to your place and we can try them out. By the way, the plain black ones that I showed you were the older design. The newer design has the lettering and the porting under the poppette seating face.

Cheers - BUMPS

PS: Nice modification to the cap.

- B

PPS: Agreed that plastic bits don't appear to wear but plastic DOES has a tendency to creep with time and temperature and we have observed that a tiny change in poppette seat apature opening has a significant affect on idle speed . I think that the lifter (spider, given its shape, could be particularly prone to creep and this could be one of the causes of the idle issues a lot of people have experienced with this carby???

In my mind Victa intended that this carby should be a throwaway item when it plays up but its replacement cost was made prohibitively high.

I think you should patent the new cap screw adjuster design for idle adjustment - simply brilliant. But just a note for anyone trying to replicate what we've done, its important to start off with an engine that idles a bit too slowly - the idle screw adjuster is then screwed in to open the poppette a fraction to allow more fuel in at idle that increase the speed. Engine can be initially slowed down by adding 7 mm washers (1 - 3) between the carby body spigot and the bottom face of the cam boss. Ie. Adding washers will raise the cam up which reduces the poppette seat apature opening so idle speed reduces. Adjuster screw is then wound down to increase idle speed to what you want. ..... But I'm still a little uncertain as the what affect the springs have on this process and there are may possible spring combinations to chose from??

- BUMPS

Bumps I now believe they are a fantastic carb once modified, very durable, pile of crap the way they were, but anyway we are over those problems. As for spring combinations I believe with the setup we now have their only purpose is to keep tension on the diaphragm so the spider will remain in contact with the cam and the only purpose the diaphragm now has is to hold onto the poppet and maybe as a gasket to prevent air being drawn in from around the cap

Really interesting design strategy by Victa in contouring the Cam such that it opens the poppette a little when throttle is moved to off / ignition kill position?
.... Seems as though they want to partially flood the engine on shutdown?
.... May be it helps with re-starting the engine when its still hot. eg. after fuel addition?

- BUMPS

(PS:

Continued from above:

But the strategy seems to work and it also seems to facilitate cold starting. I've guessed engine speed in fully choked position as being about 1,000 - 1,200 rpm.

By the way, I start the engine with the throttle set just a fraction off the kill position, pull it once and away she goes. ..... Works with either a hot or cold engine! I only start to increase the throttle opening after about 10-SECONDS of running in this fully choked position. Speed initially falls back to idle when its moved into "START" position then revs out as the throttle is moved to "RUN" position. In "START" position, at idle, the engine seems a bit happier than running fully choked - I guess its getting a bit of air at idle as the air inlet vanes on the Cam have opened a little. I've started it this way over 10 or 12 times now with 100% strike rate.

.... Nice (and no longer called "bastard" - at least for the moment)

- BUMPS