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

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

Hi Norm,

I've fixed a few mowers, mostly minor carby/pull-start/throttle/plug issues, so although it's frustrating I like the troubleshooting aspect and this is giving me a nice list to work off in the future Also I'm planning on giving this mower to my brother, so I don't mind if the cost escalates a little, I get something out of it either way

My first thought is the previous owner probably hit something with the blade holder hard enough to possibly make the mower stop dead in its' tracks, which could have damaged the bearings. I haven't inspected the blade holder yet for such damage, just an initial thought.

I'll check the movement of the crankpin/blade assembly and let you know what I find.

I would be more inclined to say the crankpin would be OK because if it were bent, even with no compression I should have more issues getting the engine to fire and the plug to spark shouldn't I?

What I can try to do to test/observe this is spin the engine slowly (Even without disassembling it) and try to view the movement of the flywheel. If the flywheel gap isn't changing while spinning the engine from the blade plate (To try to avoid pressure on the bearings) and the plug out (No pressure from the top), the crankpin should be OK.

I confess I'm kinda excited to take one of these completely apart, I've never had to before. But considering I am, I'd like to get rid of the rust on the block and paint it haha. That's one thing I've never liked about the block, I hate looking at a rusty block/muffler (OCD, can't help it haha).

More updates to come!!

These motors are so tough but run on straight petrol soon damages them and if the main bearing have been damaged enough to allow the flywheel to touch the coil(i doubt this could happen) but if this is the case then the crank pin would also be damaged (not bent but the hardening damaged) and I have not seen new crank pins for sale, they may be but if you have to rebore,if you can still find somebody who can do it, small bore rebore places are thin on the ground now,new piston ,rings and bearings ,this motor will end up an expensive rebuild. As I said earlier pick up another mower for $15/20 and good chance you could get a good motor

I'm kicking myself for not taking the buy it now mower for $20 with rotten base, but with fully functional motor and good wheels, which was in a convenient location on a route I regular drive. Grrr!

G'day Norm et al,
New OEM crankpins are available, ~$52, but you'd also need to make or buy [cringe] the special tool required to remove/fit it.

PowerTorque exchange rebored cylinders are available to the trade from GA Spares, and seem to run around $115 retail, including piston kit. These do need final cleaning before use; but that was the way Victa used to supply factory rebored barrels too!

There is however a $100 deposit/surcharge, if you don't supply a usable exchange core; i.e. it can't be already at max bore oversize, or have other damage that makes it permanently unserviceable.