OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Victa Two Stroke Engines VEX60 Power Torque 2 Won't Start

Pay 13z, your persistence is inspiring and we stand to learn at the same time by sharing your experiences. Documenting as you go makes this all the more worth while.

Sorry I have not bothered reading all that, but the needles you can get on ebay at the moment for $3.30 delivered. Once the sump is flooded it takes a lot of clearing it and until you get it all out you will not get it to start. Keep at it keep pulling it with the plug out and eventually it will clear. The fact you have got a murmer /attempt to fire means it will run but you may not get it to run without a new needle and the reason the thing is flooded is because the existing needles are rubbish.
Here's the needles amazing value, I would suggest everybody who is playing with these Victas to jump on these.
https://www.ebay.com.au/itm/Carbure...nes-G4-LM-carbies-CR03404A/123195961298?

Hi Norm,

Thanks for the suggestion, I didn't look that hard for them before and only found them in the UK in bulk. I just ordered a few (Spares help :D), ETA is Thursday/Friday though which sucks, I hate waiting haha.

I'll see what I can do tomorrow still and feedback if I have any further updates

Also thanks MF That's exactly the purpose of forums and why I'm doing it. I figure if I can document everything then someone else can just go through the list until they hit their nail on the head

I don't mean to be the bearer of bad news, but the scoring in the bore on the exhaust side is excessive. That motor will not go.

Tch tch, someone's been running straight fuel!

Hi BT & MF, so that scoring looks excessive does it? I didn't think it was that bad? And you say it's a result of straight fuel and not 2-stroke?

So even though I've got compression, it won't run? Why's that? And is my only option here to hone it and install an oversized piston?

If so, my question then is... if I have good compression now, what's the difference between having it now and having it with a honed bore and new piston?

To be clear, I'm not doubting you, I'm asking so I can learn

Cheers in advance.

Pau 13z, I stupidly ran straight unleaded in my Powertorque Mustang once and it did the grass for a good few minutes before it let out this great squeak and stopped running all of a sudden. I then realised I used fuel from the similar looking can marked four stroke!! I let it cool and emptied the fuel tank before replacing it with 25;1 and giving the primer a few pumps to get the two stroke flowing. off it went and did the rest of my yard. It did a lot of heavy work after that without drama, though it is no first pull starter. It usually takes two or three. haven't run it in two years. Will have to pull it out for a run.

Hi MF, thanks for that info, and that's essentially what I was thinking.

If the previous owner put straight fuel in and caused issues and scored the cylinder and piston that's one thing and not a good thing no doubt... but in this case, it still has compression so while the engine may not be as smooth as it originally was it should still run.

I'll keep going with the troubleshooting and let you know how I go if anyone has any other thoughts please let me know.

My plan at the moment is as mentioned above the needle/seat, muffler, and now I would add to the end of the list replacing the piston/rings and honing the cylinder, though I really don't want to just randomly throw parts at it.

I have probably 20 motors here that I suspect have been run on straight fuel, they have compression but will not start.. At this stage I would say the best/cheapest option here is to find another mower, and use the motor as a donor. I hunt them constantly and pay $10/15 for a non runner and take a chance or I will pay up to $30 for a runner. I get quite a few with good motors but the wheels/body are trashed. This then gives you time to get the original motor sorted. Just one warning on swapping the motors over the Tornados have a longer shaft and removing the blade carrier nut can present big issues if you don't have a powerful rattle gun

G'day folks,
Compression in naturally-aspirated piston-port two-stroke engines like the Victas [there are other types of two-stroke valving, which I'll disregard here] has two forms. The engine has to be good on both of these to run properly.

That is, the familiar combustion chamber compression, which is easy to measure with a gauge; and crankcase compression.

If you turn an engine in good condition over by hand, you will be able to feel resistance as the piston approaches Bottom Dead Centre [BDC] - this is due to the crankcase compression.

It isn't usually possible to measure this directly, but leak-down rate testing can be done, with a pressure pump, gauge, and suitable port adaptors. The piston has to be positioned so that the inlet port is open, and the transfer and exhaust ports closed, for this test.

Combustion chamber compression is most influenced by piston ring condition, and their fit to the bore.
Crankcase compression depends most on good shaft seals, and good fit of the piston body and skirt to the bore, assuming the crankcase joints aren't leaking.

Straight-fuelling of one of these engines very quickly results in excessive piston skirt wear, thus the engine loses most of its crankcase compression. The amount of scoring visible on the skirt can be a useful indication of this wear.

This leakage has two effects:
1. Loss of crankcase vacuum on the up stroke of the piston, so the engine can't take in a full air/fuel charge.
2. Loss of the crankcase compression on the down stroke that is required to transfer the charge to the combustion chamber, via the transfer ports. And incidentally, to purge the dregs of exhaust gas from the previous charge.

If such an engine has lost crankcase compression, the only effective repair is to restore the piston to bore fit to original specification.
This is best done by reboring/honing, and replacement of the piston and rings with oversize parts to suit.

I had a 1970s full crank Mustang with a regular piston in an oversize bore -when we pulled the head off you could wriggle the piston side to side with your fingers - yet it would start and cut grass. You had to rev it hard for it to work though.

Hi all,


Gadge, I completely agree, however never thought of testing it. FYI, after a little searching I found this:

http://www.dansmc.com/vacuum_testing.htm

In short, it says to block the exhaust and inlet ports, then perform a pressure and vacuum test via the spark plug port.

I think I have the tools to do that but without the time to do that now, I did run down and spin the blades (Spark plug out of course), and in what felt like one rotation or just under, felt resistance twice, with a small break in between.

Still to try putting the muffler back on and giving it a whirl, and still waiting on the new needle and take-down of the carby to test, but I'll let you all know how I go!

Hi all, another update/query.

So, as mentioned previously, the engine doesn't really appear to be firing or if it does it's the very occasional splutter. With the exhaust removed and spraying some SYB into the spark plug hole and adding some to the air supply, with the fuel connected I did get a couple of pops, but that's it.

I put the muffler back on and tried with no fuel, just SYB in the spark plug hole and with the mower on the bench, and I heard nothing. Now that could just be the muffler doing its' job, or it could be something else, sure.

But then I thought... I want to see it fire. So back to another test, I left the muffler on and removed the decompressor. When I sprayed fuel in the decompressor port and tried to run, the engine fired. Similarly, if I put enough SYB down the snorkel, it fired.

That got me thinking maybe yet again it was something to do with the decompressor. Tried a new decompressor again... No go.

Has anyone got any thoughts? Why would it fire with the exhaust or decompressor removed, but not with them on? Or if it does fire with them on, it's so quiet it doesn't sound like it's firing. Is it possible that maybe the timing of the firing is off, so maximum compression isn't achieved and therefore the piston isn't being pushed back down forcefully enough to continue the process?

Keep in mind, the tests I did above were performed with the fuel tank removed, so it shouldn't really have anything to do with the carby I would imagine.

Finally, what are your recommendations RE how much SYB or 2-stroke mix I should put in the spark plug hole when testing this to see if I get a few fires? At the moment, I've been putting in minimal amounts so I don't flood the engine or get the plug wet and stop it from firing at all.

Cheers again in advance everyone!!

Tried a plug in the decomp hole?

An update!

So definitely not a solution and further testing is required, but I have a good base to go off.

I tried a plug in the decompressor port... No go.

I tried spraying more SYB in the decompressor port and it fired several times.

I tried re-connecting the fuel and putting some SYB in the decompressor port before installing the decompressor to try to kick it off.. No go.

It then occurred to me... As far as I'm aware, it's only firing when there is no compression, and even when there's little compression from the decompressor... SO...

I then removed the fuel tank and decompressor and put some 2-stroke mix in the decompressor port... Glorious flames fired out from the decompressor port, dancing erotically with my VEX60!!

So with 2-stroke mix and SYB, with full compression or the decompressor installed, I got nothing. And with no compression (Decompressor removed and the decompressor port not blocked), the engine fires.

So I started searching for an answer... and voila. A reading from the holy gospel, according to Joe@ssbtractor.com (Poor English and grammar corrected):

"The problem you are asking about is common to most 2 cycle engines, the most common cause is bad bearings in the saw. If you remove plug & turn over the engine, you will see a spark at the plug tip. This is because there is no load on crank & it will stay pretty much centred up in a bad bearing(s). When you install a plug, compression places the crank under pressure which puts a lateral load on the bearings, resulting in the crank shifting from side to side or up & down. In a point ignition system, this affects the point gap. They may either open too far or not at all. This also affects the critical air gap between the mag coil & flywheel magnets. On solid state ignitions, it acts the same, on the gap, and gives weak or no spark under compression. A weak spark will be blown out. Other things to check include the correct gap on the points, a weak condenser, the air gap between the coil and the flywheel (Very critical, owners manual may tell you min-max setting), or ask the dealer where you bought the coil (usually between .08 & .012)"

Full thread here:

http://www.ssbtractor.com/wwwboard/view_all.cgi?bd=lawn&msg=10939

After reading this, something else I had heard then also made sense. If I put the engine under full compression (Decompressor port blocked), I found that I would occasionally hear a couple of pieces of metal hit each other. It sounded like it was coming from under the mower and I didn't give it a second thought at the time. What I'm thinking now is that under full compression with the bearings damaged, something is moving out of place and hitting something else. This could be due to a bearing or possibly simply a loose component.

So at this point my solution (Whenever I have time), is to disassemble as much as I can and find the loose/damaged component, most likely either the magnets/coil mounted incorrectly, or a loose bearing causing a weak/no spark.

Any thoughts/ideas appreciated if anyone has any?

Ok simple test to prove or disprove this is put a plug in the decomp and a plug in the plug hole and see if you have spark.

Come back to the forum to check progress of this thread...... the wear pattern on the cylinder is classic one after dirt been ingested - the intake side will be similar - the reason for the dead bearings.....

Is this what you meant?:


I had the plug in the spark plug port and a spare spark plug not connected to anything in the decompressor port, no spark, very difficult to pull, and I heard the "clang" sound.


Nope, the other side of the cylinder is perfectly smooth, the only damage/wear is on the exhaust side.

Ok so if you have lost spark under compression then it is possible it is moving on the crank so my next check would be to turn the motor upside down and see if you can get any movement on the crank and I'm assuming the flywheel would have to touch the coil to stop the spark and maybe that is the noise.For it to do this the crank has to probably move 20 thou and I would be surprised if a motor could run to get that much damage to the bearings

My last point on this motor is that if the main bearing are damaged to the point that the crank can move enough to hit the coil , the big end and crank pin must be well on the way out and seeing a big end bearing will cost $40, a donor motor is the best option