OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Victa Two Stroke Engines Victa Tornado 19 Inch Cut 2 Stroke

On the weekend I aquired what I thought was a pretty good score for $5 from the junkyard. After a carby clean I got the mower going however I had virtually no rev range when adjusting the throttle. I thought what the h*ll lets strip it down and take a look.
Below are photos of what I found. The piston wasnt scored on the exhaust side, the rings where in really good condition however just beside the gudgeon pin circlips on either side of the cylinder there are strange marks on the piston.
Even stranger is the fact the bore is virtually unmarked. After further investigation I established the block has either been honed or bored as a new standard piston I tried in the bore was too small.
I have not encountered this before and would like some confirmation on how to proceed. At this stage I will deffinately replace the bearings however I am not sure about the piston at this stage.
I appreciate some advice as this is strange to me. I would also like to understand what causes this.
Thanks
Peter

Can a moderator please look at the pictures? I uploaded them the same way however they came up with errors. This hasnt happened before.
Thanks
Peter

The pictures look fine to me, Jaffa. I won't comment on the engine of course - I have a negative view of Victa 2 strokes and never discuss them.

Ok thanks Grumpy. I am more interested as to the cause of these marks so I can create a fairly reliable machine. My experience tells me worn bearings may have been to blame but I'd like some further clarification. The conrod had no pits on the big and little ends so that didnt concern me. I would have thought that when you honed an engine like this you would install a new set of bearings?

What I would like to know is if others would re-use the piston and rings (rings were in excellent condition)?

The block has deffinately been honed. My standard finger nail test in the bore revealed no deep scores at all.

Hi Jaffa J, Joe Carroll is our resident Victa guru and hopefully chime in here with some advice....
If not, send him a PM.

Carefully check the top of the piston for an oversize mark, I find it uncommon for a powertorque motor to get bored, its so cheap and easy to get a second hand block.

What I am aiming at is, There are early and late powertorque pistons for the new geberation engines, they put the ring gaps in slightly different places, I am pretty sure from memory if you used an older style piston in a newer style bore it will foul with the transfer port. On the other hand a newer style piston WILL fit into an older motor.

Either that or our famous china cast metal has had a bad batch again

I thorougly cleaned the top of the piston and it does not have an oversize mark which is what I found really strange.
I was testing the block with a new bynorm piston without the rings on when I thought it was just a little too loose for my liking. With the rings on it should be ok however I think?
My understanding of the blocks and pistons in the same. New style piston in old block = ok, old piston in new block = smashed up rings due to re-sizing of transfer ports.
The block has definitely been honed and not bored as you can see ever so slight swirling marks. It has no deep scores so its still good to go!
Id love your opinion for longevity in this instance and NOT the cheapest fix. I do want to keep it economical however as the mower ran quite well before I tore it down for re-furbishment.

Thanks

ideally I would be taking a measurement of the diameter of the bore, not at the top as the top doesent wear nearlly as much as a bit further down and comparing it to the tolerances in the manual (I do not have the manual on me at the moment.) if within spec a standard piston would be fine, how loose does the old piston feel in the bore as compared to the new one? I have used ones with similar damage in rebuilds for myself before without a failure yet but it can be hard to tell just how much damage it has without looking at it in person.

Thanks joe. The standard new piston was way too loose to use when compared to the original.
I had a close look and think about it and decided to re-use the piston as the marks were only light. The rings were also spot on with no wear. I did however install a new set of bearings.
After inspection of the original bearings I am confident they are the originals.


It's all back together however it's got good spark and nice clean carby so I'm confident it should be all good!

Thanks for the advice.

Joe, the mower came up a treat. I gave it a solid workout and no problems at all. It amazes me how people throw out such expensive mowers.

Thread can be closed.

Good to see everything worked out, sometimes people have too much money and throw these things out.