OutdoorKing Repair Forum Forums Collectors Corner Rotary Victa Corsair scored cylinder

I've taken the muffler off and you can see the scoring on the piston, it's only around the rings section, the rest of it is smooth. the rings seem to be glued onto the piston, I cannot dislodge them so no movement there. Are these photos sufficient or do I need to take off the head, having said that even getting the muffler off is hard enough on these?

The scoring does not feel very deep from what I can feel, what do I need to do now?

Have you carefully put a screwdrive blade in through the port, and pushed the outer surface of the ring toward the piston? The issue is whether the ring is stuck in the groove, or is capable of moving a tiny amount radially. The rings can become stuck in carbon so they won't move - when that happens they will not seal, and combustion gases blast past them, eroding the bore, the rings and the piston ("blow by"). If the rings are actually stuck, you need to remove the piston, remove the rings from it, clean the ring grooves, and almost certainly, fit new rings. I can't tell from the pictures whether your rings are stuck.

A bit of mild scoring on the upper part of the piston between the ring grooves is not of much importance, as long as the body of the piston and the bore are not scored.

Grumpy, I couldn't move them at all but I was going pretty softly at them with the screwdriver. There was no movement that I could detect with the rings.

I'd be inclined to put the screwdriver blade against the ring, and bump the end of the handle firmly with the heel of my hand. If it doesn't move then, it's stuck.

Tried that Grumpy, no movement noticed. If the rings are stuck, what next?

Grumpy just read your other post where you described what I had to do with a stuck ring, how much of the engine do I have to dismantle to do this?

You have to get access to the entire piston to remove the stuck rings then clean the ring grooves before fitting new rings. On most Victa 2 strokes you can unbolt the cylinder from the crankcase then slide the cylinder off the piston. However I avoid all dealings with 2 stroke engines, so I'll leave answering your question in detail to someone who likes them.

Hello tiger,
My series of images on page 1 of this thread may help you.
Your sequence to clean the rings are:
Image 4: Remove starter, 3 x 12mm bolts
Image 5: Stop the piston & crank moving (use rope or piece of wood, place it in front of the piston, put head back on or lock the blade boss in a vice)
Image 6: undo crankpin, there are spaecial tools to do this, some use a punch or screwdriver, using care to loosen it.
Image 8: remove head, 4 x 12mm bolts.
With draw piston to inspect and clean it.

Let me know if any of this makes sense.

Decided to take a look at the Victa Corsair again. Took the starter mechanism off and found that the o-ring that sits under the Starter housing assembly was broken and perished. I've taken off the cylinder head to examine the cylinder and it actually looks ok ie just a little bit of scoring. I can't see much of the piston but what I can see is a little bit of brown possibly burning on it. I had a go at trying to take off the crank pin just using a hammer and screwdriver but it did not budge. Suspect rings still but need to get a closer look at the piston.

Gone a bit further and was able to get the crank pin off eventually.

Photos attached of the piston, cylinder is in good condition. I was wrong about the rings, they actually do move quite a bit, the piston is scored on the exhaust side but otherwise in good condition. I'm now confused, if rings are ok, cylinder is ok, what next?

G'day tiger,
there is scoring on the piston and top ring, I cant see if there is any in the bore.

I would replace the rings and reuse that piston. Make sure scored metal has not entered the ring groove.
(Give the scoring a light clean up)

Forum members have taught me in the past to, carefully remove the rings (they can snap)
Removing the old ones is practice for replacing the new ones.

Then clean carbon out of the ring grooves using a piece of old ring ground flat so that you can use the edge as a scrapper.
Try not to remove any metal.
The intent is to have a snug fitting ring that can move freely in its groove.

Things to notice: where the pins in the grooves are located to avoid the transfer ports, how the ring fits around the pin when compressed, thickness of rings.

If you have scoring in the bore you will get combustion gases passing past the rings.
Here are 6 blocks I stripped and honed today. They are in order one to six.
I was looking for good cylinders to use for rebuilds.
What I use, I'm not exactly sure of yet.

G'day Mark, there is some light scoring on the cylinder but not much. The top ring on the piston was stuck at the point where it must have overheated. I gently moved both rings and now they are both moving freely although the top one feels like it has grit underneath it. Tried 2 mower places today for new rings, both said they didn't have any and would have to get them in. Is there any point in trying the current rings once the groove has been cleaned up?
Appreciate the info on rings, I didn't think there was that much to them but you've saved me some grief. Notice that you said that you honed your cylinders, is it worthwhile me doing the same on my cylinder?

I think that since you have gone to the effort of pulling the piston out, you should do all you can to make the best engine out of what you have. You will be rewarded with and engine that starts easily and runs well.
You say the bore has light scoring, is it like any of my images above?
The first three blocks above will definately go to scrap metal.
I will use the bottom two.
The rings need to seal against the bore as it travels up and down.
Rings are available on ebay for a small amount.
I only hone the bore if I think it needs it.

I reckon mine resembles no. 4 the most. Not as good as 5 and 6 but a little better than the top 2. I hear what you're saying about the rings and I did try to get them yesterday. It's just that the mower is in parts everywhere and I'm eager to get this mower working again. I'll have a look at ebay and see what's around.

You can get the cylinders rebored and a kit (exchange) would start at a cost $99.86 (depending on cylinder type)and that includes the piston assembly and rings.

Thanks Bruce,
I certainly would like to have some rebored blocks with pistons to match.
I have always felt uncomfortable ditching a scored block.
I will put these aside for now then.

tiger I forgot to mention the rings are available at outdoor king, search victa rings and they will pop up.
We are working on similar machines at the moment, I have this one ready to assemble after lunch.

Hello again, just thought of something else to check: tiger look at the crown of your piston for any stampings.
like .20 or .40

This would mean your cylinder has been bored out oversize at some point & would have a piston to match.
If that is the case, then you must get the appropriate oversized rings.

Thanks Mark for your help, I have bits and pieces everywhere but not much room hence the need to get the thing back together quickly. Will check the piston for any markings. Does anyone have any guidelines for when an engine needs a re-bore, there's some discrepancy I've noticed about when you do one, someone here was saying that even with a scored cylinder that a Victa could still run?

Hello tiger, to answer you questions as best I can from what I know, yes your Victa would run with the scoring I have seen in your images, the issue is how long would it run for ( "longevity" or "life expectancy" )
I think every person has their own level of what is acceptable.