OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Victa Two Stroke Engines Old Victa 2 Stroke Idle Problem

Hi everyone,

I have this problem with my old Victa 2 stroke 160cc lawnmower, it's the one with the back plastic carby on the old full crank engine. I have replaced the rubber seals that sit on the intake side of the engine for the carby. I have also just today replaced the carby fuel float, needle, brass inlet screw, the plastic cap with the rubber primer on it.

I still can't seem to be able to adjust the idle on the mower at all. The screw on the back of the carby has been screwed all the way out and the idle is still pretty high. The revs still work ok with the carby lever on the handle. But I just can't seem to get the revs low enough when in the idle/start position.

The cable still works fine that connects to the carby, I have installed the needle the correct way for the float.

It's just a bit annoying when trying to empty the catcher and the revs are still quite high when it's back in the idle position. The screw on the back of the carby I have sitting all the way screwed out, it basically isn't doing anything at all for the adjustment of the idle.

Any help would be much appreciated.

Cheers guys!

Air leakage into the intake pipe or crankcase is the usual cause of excessive no-load engine speed with crankcase induction 2 strokes. You said you have checked for intake pipe leaks, but you did not say you have looked for bad crankcase seals. On some of those Victa engines one of the crankcase seals sometimes works its way out of the housing, allowing suction leaks into the crankcase.

If it is not a suction air leak, there seem to be two main possibilities: the governor is malfunctioning, or you are expecting a lower idle speed than the governor can give you. I know people fairly often complain about the minimum possible idle speed of the Powertorque engine. It is high by design on that engine, because it needs to be. I do not know whether the same complaints arise with the full crank engines that had the black plastic carburetor, though.

Thanks for that Grumpy, I had the engine fully rebuilt by a lawnmower shop a few years ago. Can't quite remember now but I think it may have been running a bit faster at idle ever since I had the engine rebuilt. I have cleaned and rebuilt the carby a few times over the years and it's still pretty much got all the original factory rubbers and springs in it from factory. When I got the engine back from the shop I bought new rubber seals for the intake parts of the carby to make sure that it seals properly.

How would I check to see if these crankcase seals are leaking?

I thought that maybe the fuel float and main jet may have been the problem with the fast idle, but after replacing all those bits with new parts it hasn't changed the idle speed at all. So it's definately something else that's causing the fast idle.

The air snorkle is in really good condition with no cracks or leaks, so I don't think it's got a leak anywhere from the air filter all the way into the carby, it might be the crankcase seals as you mentioned, or maybe something inside the carby where this governer and the idle adjustment parts are located.

Thanks again for all the help mate!

Just a quick thing before you go disassembling the hole engine, as this might be a more common issue to this carburetor, with a simple solution.

Grab a couple of THESE and pop it under the throttle cam.

Like this:



I can't guarantee it will work, but this is a common fix, to a common problem, and is pretty cheap, it also might save you worrying about pulling the whole engine down.

Also, is there definitely some form of metal clip inserted on top of the diaphragm?

An air leak upstream of the carburetor will not affect the idle speed. The crankcase seals I was talking about are the ones between the crankshaft and the crankcase - one at the bottom above the blade plate, and one at the top under the flywheel and magneto. The seals are just plastic, pushed into bored recesses in the crankcase halves. Because the pressure in the crankcase increases sharply once each engine rotation ("crankcase compression"), there is a pulsating pressure 50 times per second, trying to push the seals out. Sometimes it succeeds in pushing them permanently out of their recesses, and air can then be sucked around the outside of the seals, into the crankcase in between pressure pulses. Also, the plastic seals rub against the crankshaft at high speed. The bottom seal, above the blade plate, is prone to wearing out due to dirt and grit, or bits of grass and string getting wrapped around the crankshaft and cutting into the seal so it leaks.

You can check the bottom crankshaft seal by disconnecting the spark plug lead then looking at the bottom of the crankcase by peering in between the blade plate and the mower base. If the seal has been pushed out you should be able to see that: there will be a round piece of plastic visible below the bottom of the crankcase. If the seal seems to be still in its recess, you can drain the fuel from the tank and turn the mower upside down, then you can squirt a little bit of oil onto the crankshaft just above the seal, and see if it disappears into the crankcase. If it does, the seal is not sealing. To make a similar check on the upper crankshaft seal you would have to remove the flywheel and magneto, which I don't recommend as long as the mower is working properly. If you have an air leak into the crankcase, unless it is rather a small leak, the mower will lose power. If that happens, the leak has to be fixed, but until then, it may be best to leave it unless you are comfortable with pulling the flywheel off (it is on a taper, and will require some special persuasion - we can talk about how to do it if you wish, or you can read about it in Outdoorking archives).

As Mr Davis said, if there is nothing wrong with your mower and you are just objecting to Victa's chosen idle speed, you can modify the governor (it is inside the carburetor, behind the diaphragm) to reduce the idle speed, by adding an extra washer where he has shown on the diagram. I don't recommend that, since you would be modifying Victa's intended minimum speed, but it is sometimes done by Outdoorking members.

Actually Grumpy, this is less about modifying Victa's speed, and more about restoring it.

The engine in question is either a Series 70 MKIV or a Series 80, so at it's latest, this is still an early 80's machine, most likely running a G4, but possibly an early LM.

This form of issue is very common with these carburetors, after this length of time, particularly after disturbance to the carburetor (issue appeared greater after carby was rebuilt)

Over time the lower part of the cam stem wears, lowering the cam, and in turn the lifter, this lowers the idle position for the diaphragm, resulting in a higher idle.

The washer in question is a part made by victa to correct this issue.

Further, the large metal plate used to lock the diaphragm in place can cause a set of issues of its own, and at service time, many repairers simply remove it, however, it is always a good idea to replace it with the smaller type in that case, to prevent the poppet tip wearing through the rubber diaphragm, often here, due to the smaller clip being thinner, the same issue can occur, and the same washer will remedy the situation.

So the washer is an official Victa service fix for a wear condition in the governor. Kind of similar to Briggs' official service fix for a bowed fuel tank top with the PulsaJet carburetor: put a tiny roll pin in a convenient hole, and fit a miniature teflon washer to stop the fuel leak.

Thanks Ty, I've always thought it was just an unofficial "tenant's improvement" rework to modify the idle speed - I've seen people advocate using several washers to achieve that. In this case the carburetor has the original parts in it, so a wear problem seems to be very much on the cards, and the service fix would be a worthwhile step to take.

It can also be used to adjust the original speeds, I believe a max of four washers, however I don't think its a good idea to go changing the original governed speeds, and only one or two should be needed to fix the wearing issue.

Hey there Mr Davis and Grumpy, thanks for all the tips and help it's great.

Seen as the seals aren't that expensive I have replaced both the top and bottom seals today. They actually looked pretty good, although underneath the top seal it seems like there was a little bit of oily dirt sitting on the bearing. Maybe there was a slight leak from the top seal? I cleaned it up and replaced with a new seal. I also replaced the decompressor with a new unit as it was still the original factory Victa item from the early 80's and maybe it wasn't sealing the best.

I have not touched the carby at all as a bit of a test until I get it ready to run again to see if changing the seals and decompressor will change or lower the idle speed a little as maybe it was a leak somewhere.

If it's the same then I should be pretty sure it's somewhere along the inlet where the carby sits or something wrong with the carby itself.

For the sake of a few more dollars I will grab new rubber seals for the inlet where the carby sits.

Thanks for the diagram Mr Davis yep that's exactly the same carby that i've got, it's all original as in the diagram. Nothing has been modified from factory on this one. If there is no leak anywhere in the system then I will try adding this washer there to try and bring down the idle a little bit.

Yes i've had the lawnmmower since new and I do remember many years ago the idle was a fair bit slower than what it is now. I'm just trying to get it back to the original factory idle speed.

Thanks again for all the help guys, I will get back to you again and let you know how it all goes.

Cheers!

G'day again guys,

Thanks again for all the help and advise on this issue, I ended up changing the top and bottom seals and the decompressor valve to make sure there was no leak in these parts. I started it up and it was slightly a little slower in the idle. So there may have been a slight leak in one of these seals or the decompressor valve.

But the idle was still too high and I still could not bring it down slow enough like it used to be years ago. So I bought the brass washers from Bruce here at Outdoorking, chucked in 2 just like you mentioned. Put the carby back on tried to start it and it wouldn't kick over. That would have been because I still had the idle screw turned all the way out to the point where it was nearly falling off the housing.

Once I turned it back in to where it should roughly be I now have a fully adjustable idle again! It's awesome! I can tell you that those 2 washers installed in the carby definately fixed my idle problem!

It now has full adjustment right in and it can be brought to quite a fast idle, start to turn it out and you can actually go to far and stall the engine. Full manual adjustment! Very happy with the result!

Cheers and thankyou very much for all the help Grumpy and Mr Davis, you guys are great!

Cheers!

That is a great result Converse, thank you for letting us know. It might be better to use just one washer, rather than have the idle butterfly stop screw controlling the idle speed, but it is clear that you have sorted out the whole issue and removed the faults.

Wonderfull news Converse, glad it came out well.

Just as a note Grumpy, the screw in question here is actually a large plastic screw at the end of the carby, that the govenor poppet valve tip rests against, when in idle, the main throttle cam has the throttle valve legs opened to a set point (no butterfly in this carby) and adjusting the knob will move the poppet valve in and out, which is a second valve, closer to the intake.

The range converse has described is quite normal, the G4 carby was alot more adjustable than the similar LM carby, at least in terms of idle speed. and while a good result would probably be acheivable with one ring, the outcome here is exactly as should be expected from a well functioning Victa G4 carburettor.

Thanks Ty, on that basis I will retain my preference for having no dealings with Victa carburetors.

To each their own, the plastic carbies are not bad to run, or hard to fix,but personally, i feel they lack the soul of the meatl carbies of earlier days, maybe thats just the collector in me comming out, but i am a sucker for the Victa G3, heck, if i get bored, or have a spare moment of an evening, i dont watch TV anymore, i just pop out to the shed, and restore a G3, they all sit on a shelf, awaiting mower projects.

I'm also enjoying working with a few of the brigs ones that i am starting to get into now, I quite like the gravity fed one on my quantum, and the pulsa-prime is my favorite of the tank mounted ones, I have a few nighe little auto choke ones here, ready for machines

Perhaps I'm just a carby addict, the detail of them has always excited me.

I have the same idle problem on my mower which is a victa 2 stroke with a G4 plastic carby

Thanks guys! Have one on a utility same idle problem, I suspect seals, but will now check out this mod....hours of forum reading paying off.....

Here is a video by junkyarddog87 (Joe Carrol) on the problem

Great video/information Im gonna give it a shot, thanks again....

[quote=mika]Great video/information Im gonna give it a shot, thanks again...


Followed the video instructions, also replaced the O ring on the primer cap.
My green machine is idling like it should be....very happy.

Cheers Guys for all youre Help
Mick

Hi all, been a while since my last visit been a bit crook but all good now.

I have this old victa power torque Model BA080A5 that I was given and have finaly got it going but I have this strange throttle problem.

Once started - push the throttle to run and it revs flat out - bring it back to start and it idles - bring it further back to stop and it revs up agin.

I have checked the throttle cable at the carby end and it opens/closes as it should.

Note: I have bye-passed the kill pins and put a on/off button as I could not get the pins to work but the on/off button woks fine.

I also note that the diaghram you have, shows an idle screw that fits into the cap - on mine (I have 3 power torque's) there is no provision for one of these but the rest is exactly the same, even has the extra washer.

I also watched the video it's very good.

Your thoughts appreciated
Regards
Rich