OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Victa Two Stroke Engines Victa 160 Plastic carburettor

Dear Ihatewetsocks,

I can confirm that the diaphragm was correctly installed.
Thx for the suggestion
- BUMPS

All,

One additional thing I should have metioned regarding the poppett is that I has a choice of two - unmarked black poppett or the newer style white poppett with the lettering and the short spigot on the moulding. For no real reason I chose to install the black poppett. If the engine still doesn't run properly after fixing the broken ring issue, should I change the balck poppett for the new white poppett and installing it as described on the earlier posts - Letter "C" facing the carby spray hole???

One other matter that may be important - all the carburettas that I stripped to produce one "good" on had the large diameter clip that secured the diaphragm. I noticed on the parts diagram that cyba-jack provided that one view showed a small circlip as the means for securing the diaghragm. Given that the 4- carburettas that I stripped all used the same large diaghragm, could this mean that all carbys were in fact the same model?


THX - BUMPS

That's why I wanted to to squirt some areostart down your air filter tube as I really thought you were not experiencing carby issues.There not the sort of problems you have with these carby's unless the accelerator isn't connected.I was trying to get to that but I guess in this occasion you just got bombarded with to much information and was taking note of every one.Don't worry it does happen especially when you have three people helping and three different views,but I guess that's what happens on open forums.

Stick with the black poppet value the white one is the older one and the black one should be fine to use.
The cir-clip ones were from the G4 carbys only,the LM's didn't have them.As was shown ealier
Heres another look.
Top two G4's (Of which I'm fairly sure you don't have).
Bottom two LM (which most likely your would be).




If you could post some pictures of what you do have,then that way instead of chatting about the differences we could help with what you do have.

so the powertorque didnt have the small clip ? and the ones i have pulled down here have all been changed i guess . early to late ones too . seems they use either or but enough , good luck with it mate , hope it works out well

I guess it's like everything vccomm use up all the old parts first before using the new ones.
My documents show from a Technical bulletin that the LM was introduced in November 1978.
So I'm guessing that the older bits could still have been used,after all from a business scene it would be silly just to throw out parts that can still be used.This is making me want to count how many G4's I need and ask if anybody has any.I should as I know I'm short on them.

OK well due to this particular topic I decided that I'd better have a look at what G4's and LM's I have and what are some of the differences.Just before I go any further I think somewhere above I have made the wrong statement.I think I said that the earlier G4's had the white poppet values and the LM's had the black.Sorry I think that is around the wrong way.Not sure why I wrote that but I did.
Now vccomm yes I found also that a lot of my G4's had had other updated parts put them I guess due to work being made by a Victa dealer and I too found other diaphragms changed to the newer ones but I still stand by what I've as I have documents that state this and the changes that were done by Victa.
Here is some pictures to help with the things that were different.
Caps.G4 left LM right.

Main Jet G4 left LM right.

Diaphragms G4 left LM right.

The same here,G4 left LM right.

Poppet valves as far as I know there was only three types.If anyone really wants to see the shape difference between let me know I have other pictures to show the difference.

Bottom side I hope you can all see the letters we were talking about earlier.



All in all I had fun checking the changes and seeing how many of each carby I have.Now to work out how many I really need for my collection.

Just re enforces the fact that the first step is ALWAYS know the condition of your engine FIRST

I agree I always make sure engine is worth my time to start with. However when I first started I did the same just jumped in and then found problems. I guess it's how we learn.

Excellent photo Blumbly but one quick question:
Are the three poppetts all the the same length?
....... I'm trying to acertain if one type was specically made to suit the idle adjuster screw on the caby cap? ie. Given that my adjuster has no affect on engine speed it may be possible that the screw is not contacting the poppett and forcing it down to either limit or increase the idle speed?

Are there any comments as to whether a bottom broken ring could cause spasmotic engine operation under no load conditions??? I'm going to replace the rings of course but I thougtht I'd ask the question.

Thx- BUMPS

Yes the poppet valves are the same length they just have different groves and step ups. Expect the black one is just all round and a smooth surface. They all will work with the idle adjustment screw. Just have to make sure the large spring is in place.
Yes broken ring or rings will cause what your problem is. I've found that with 2 strokes they will run with broken rings ,but just have problems like you've found.
I had one of my Twins run and run well it just didn't seem right. I thought it was a vacuum leak or a decompression valve problem. I found (when I pulled it apart to restore it) that one cylinder had two broken rings and a chunk out of the piston,but it still run ok.
So yes that will be your problem.

As Blumbly says Bumps, broken rings will cause running problems in a two stroke because they will cause a loss in compression. Depending on the sealing of the piston in the bore, the symtoms can vary often making it hard to work out, From what i understand, the biggest difference between the 125 and 160 motors was the hardness of the bore and the thickness of the pistons, this resulted in 125's still running , and often really well, with next to no rings left as the sealing was so good, where as the 160 barrel was a lot softer and piston much lighter resulting in wear that affected the running much earlier. combine that with worn crank seals etc, etc, it's mostly why it's the 160 that causes headaches.....

Also with a 2 stroke they (being the rings) have to suck (or have compression) on both the up and down strokes. As to pull the fuel air mix from the carby and through the crankcase to allow for the bottom end to be lubricated. Then pull the fuel mix into the combustion chamber. Where as 4 strokes only needed compression on the backwards stroke. Due to having a sump with oil to lubricant it's bottom end. So less work is needed by the rings in a 4 stroke.

Giday all,
Just a quick note to say thanks to everyone who assisted in this battle.
Case is now closed! .... Replaced the broken bottom ring (top one too but it was OK) and engine sprang into life. It now starts easily, idles beautifully and revs out ro full speed. I was really surprised with the problems that one bottom broken ring posed. Every issue I had with the engine pointed towards the carby but I was on the wrong tram. One suggestion however still puzzles me a little - I think it was Blumbly who suggested spaying Aerostart of "startyahbastard" into the air inlet to determine whether it was carby or "something else" .... I must query how spraying this compound into the engine would help diagnose the problem .... Could you please expand on this fault finding tool??
Anyway it was an interesting journey compunded by the may changes Victa had made to the G4 and LM carburetta ove the years and the uncertainty that exists when a novice strips several units and then mixes up all the parts and starts the reassembley based on using the best bits and the fact that every item mechnaically fitted together.... there were different length main springs, different caps, different poppetts, different diaphragms and even the cams that had subtle differences to their countour profiles(but they did have different part numbers moulded into the unit)and all the bodies "appeared to be the same but part numbers had eroded away so it was impossible to tell if they were in fact differenct from one another. I've attached a few photos to illustrate the differences. I've also added a photo of an Amal 361/1 that I fitted to a Victa 160 for use on my Grand Childs go-Cart .... It superior in every way to that heap of plastic shi#t that Victa produced. I did a lot of research on trying to locate another one but there as scarse as an honest politican ..... they were used on a number of mowers and stationary engines in the 60's msot notably the "Hurrican" Engine (manufactured in Sydney) but Amal (UK) originally supplied it to BSA for use on their 125 cc Bantam D1 motor bikes in the 1950'2 and early 60's. There is a huge cult following in the UK on restoring and even riding the old Bantams and the Amal 361/1 is highly sortafter and I can understand why ....it really fired up the Victa 160 and the gocart literally flys....... and such a simple robust design and manufacture! ...... Don't know why Victa didn't follow Hurricans lead and use them as well???
Anyway as I opened up with .... Case closed!

Well done Bumps and a great outcome, one of the best learning curves possible!!

Bumps I was just looking around and stumbled across this, I realized you had been struggling with this motor for a long time but I didn't think it was quite that long. Anyway we now know how to solve the LM carbs and can mix and match any parts from a dozen carbs and get them to work as a carby should work with a tick over idle and full control over whatever revs you need depending on how high the grass is you are mowing. Great carby once setup, but most things I have read about getting them to work is just folklore and myths