OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Victa Two Stroke Engines Popping when starting engine after rebuild

Thanks Gadge that gives me something to study so I can understand these engines better.

I got to admit there is strange designs I have seen but that what makes working interesting for me. It probably the same for our designs here too. Knowing how these works just makes us better techs.

I presume you are referring to lack of lubricant in the ether.
I don't think a handful of revolutions of the engine would harm it as long as it has run recently with some residual oil present.

Partly that; mostly that if the shot of ether is overdone, it can detonate with sufficient force to do physical damage to engine components. This damage can be in the form of cracking, which may not be immediately apparent, but will cause big trouble later on.

The only engines I've encountered where diethyl ether was routinely used for starting, were old hand crank start [or direct air start] diesels, which were all built like tanks. These had 'plug' stopcocks, with cups on top, mounted on the cylinder heads, for pouring in a measured shot of liquid ether.

I sprayed a small amount down the air intake hose, which didn't do anything, so I sprayed a small amount in the carb where the air intake connects, also did nothing.

I tested my plug in a running mower and it works fine, so I've narrowed it down to lack of compression or ignition/timing.

I will purchase a compression tester on the weekend and measure the compression.

I'll keep you updated with the results.

Compression tester is not needed, you told us very early on it would lift the front wheels off the ground without the blade carrier fitted. These motors will still run with very low compression. I have run these motors for many years with the decomp valve plugged without problems because the compression was so low but they cut the grass without issues. Remove the decomp valve and fit a spark plug and pull it over, you will find the compression is adequate for it to run. If you have spark the timing is correct because you can't alter it. You say you have spark, compression will be fine, only leaves one thing missing, fuel. The only other possible cause could be a leaking lower seal on the crank. Have you removed the inlet manifold and lost the seal

Removing the decompressor is rather hard on the starter mechanism, though - they're pretty lightly built, compared to the recoil starters on the pre-Zip Start Victas.

Easy enough to overcome with a full-crank engine though - just leave the starter [or top cover, in the case of a side starter model] off, and use the leccy drill start technique!

Gadge, the ones I used with the decomp removed were full cranks fitted with rope pull start and I was using those probably 30 years ago, my point was to say that with very low compression they will still run ok

Ha!! My first VC Mustang had a piston you could wobble inside the barrel and it still ran and cut people's grass. You had to rev it at ludicrous levels and use the momentum from the flywheel to do the work. It sounded like an air raid siren at full cry.
I ended up selling it to a mower shop for spare parts and got $20 for it during the 1990s.

I checked the o-rings, both there.

Here is a video demonstrating the spark, just to confirm it is enough. It seems a bit weak when pulling the starter cord slowly. I'll let you guys judge...

I'm thinking of swapping out the flywheel, what do you guys think?

[video][/video]

I don't look at utube but if it has a weak spark when pulling the cord slowly then I would assume the spark is good when pulling it quickly so why change the flywheel?
Mowerfreak, I had one of those motors where the compression was so low I had to put my finger on the pull start pulley to prevent it turning while I wrapped the rope on it because it wouldn't come up against compression but it still ran well and cut the grass for years

And to add to this I also have some Powertorques that won't start for some reason, but as I have these motors everywhere it is easier for me to just swap out the motor that won't start and replace it with one that does. I guess one day I will have to confront the reason why they won't start and that will only happen if I stop buying these mowers from ebay and gumtree. The big problem is I get plenty of these mowers but the bases and wheels are usually shot, but the motors are fine. I would say I probably have at the moment 5 motors to every base and wheels. With the Rover stuff it is the opposite, 5 bases with good wheels for every motor because they use Briggs motors on them. If you could fit Victa motors on the Rover bases it would be a good combination, but I guess this would not be in a manufacturers interest, they have to make something wear out/fail www.outdoorking-forum.com.au/forum/ubbthreads.php/topics/81193/Powertorques_that_won't_start.html#Post81193

I probably have at the moment 5 motors to every base and wheels. [/quote]

Hello Norm, you wouldn't happen to have a fuel tank for a Cortina 70 Series? Picture of my original one is on this link below.

https://www.outdoorking-forum.com.au/forum/ubbthreads.php/topics/83055/Re:_Victa_Cortina_Series_70.html#Post83055

Best Regards, Renzo

Hi Renzo, not sure, there is mowers here I have never even looked at, is there anything special about the Cortina fuel tank. I guess the fuel tank is removable from those metal cowls, years since I looked at them, not sure if they can interchange

G'day Norm,
Just to be sure we're on the same page here, the self-retracting rope starters are what Victa always termed 'recoil starters'. The wind-up ones were 'impulse starters'.

Hi Gadge, I'm talking about the pulley on top and you wrap the rope around, not those fancy new fangled impulse starters

No worries then, Norm.
That setup is more correctly termed a 'lanyard start'.

The early Victas didn't use rope lanyards, but square section leather ones! When my family bought an established OPE/farm machinery business in 1973, the Victa spares old stock included NOS leather lanyards, in their Victa skin packs...

For those of you that may still be interested in this topic, I decided to rule out the head gasket and starter o-ring, so I replaced both today with no improvement.

I'm officially calling it, this one is dead. I've got a couple of spares, so I'll just bolt one on. What do you guys do to freshen up an old running engine? Just clean the ports? Is it worth rinsing out the bottom end with fuel to wash out any debris that may have made it in?

Hello greens_tuf
That's unfortunate - that there was no resolution.

I sprayed a small amount down the air intake hose, which didn't do anything, so I sprayed a small amount in the carb where the air intake connects, also did nothing.

I guess you went through every check - including whether the
crankcase seals were affecting the scavenge of fuel; and you would
have tried a different spark plug... and ...

This is a great project - love the images!
Please let us know what is the outcome.

---------------------
Jack

Thanks Norm, Yes the tank for the Cortina needs to be the correct one to fit under the metal cowl.
Regards, Renzo

Hi Renzo, can you post a pic of it so I can see what it looks like