Best piston
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@glynn123
https://imgur.com/gallery/OvdhjwgHere's the state of my old cylinder. Not sure it was because of the piston but this doesn't look very nice at all. There was this horrible knocking/rattling from the cylinder for those who remember. That's why I decided for the Athena really.
6000km piston https://imgur.com/gallery/Koz7v5j
Here's the piston, about 6000km on it.
Looks pretty okay I guess. I've removed some carbon on the top to look for signs of detonation and such. The carbon build-up isn't actually that bad. -
On this piston, I can't see any signs of piston slap.
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Think I found it, I mean if you buy this shit, you shouldn't be legally allowed to own a motorized vehicle...
I can only imagine what @Calum must think
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@irongamer727 That new Forged Vertex one I've just got is going to slap like a BIATCH!
Massive piston to wall clearances.
It's hard to tell from the finish how decent a piston is, to really appreciate it you have to understand the properties of the alloy they used. This gets above my comprehension level and I leave that to the professionals.
But in my book, "Tuning For Speed", Irwin explains what type of alloy is best used for each application. And more interestingly, the best places to get such metals. Namely Birmingham England (about 40 minutes drive from me), whilst referencing the company. Bare in mind this chap is from Australia, so the fact he's referencing something from across the globe is pretty impressive.
Alas, our manufacturing has since long gone. But a good book never the less.
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@calum why would you want big clearances? I measured the bore and the piston and the diameter was nearly the same. To tight is not good of course but I can't imagine why a performance engine would want big clearances.
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@irongamer727 It's the thermal co-efficients of forged components which is why there are big piston to wall clearances. Forged components will expand much greater than weaker cast components. Which means the gap will close and it will be fine, but this makes it absolutely paramount that you wait for the engine to get up to operating temperature.
Same thing as my Starlet.
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@calum oh now that you say it I remember.
I mean I would not be surprised if my previous piston has expanded a bit too much in the cylinder.As you can see on the link there is like a mirror finish in the exhaust and inlet side. I don't have a clue where the ticking/rattling sound came from though.
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My wossner was absolutely silent when I first rebuild the Dt, had a barrel bored to match the piston at the recommended tolerances from wossner. Hundred miles on it started getting rattley, it's now pretty piston slappy at the top end but checked 1000 miles on when headgasket went and piston and ring tolerances were perfect haha, makes great power and starts good so I'm not worried, never heard a good running two stroke any better really, it's when they're silent you need to worry haha.
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@irongamer727 Sounds more like glazed bore which is due to incorrect run in procedure.
I've switched from Wossner now, after PJME have advised they've started manufacturing their stuff in China.
Now China has some of the worlds foremost engineering plants in the world. It's their QC that lets them down.
I've now switched.
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@calum is that cylinder scrap? The piston was 58.4 mm. So I guess it is soon no point boring that cylinder? Not that I will use it again.
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@irongamer727 You can go overbore. Really need to modify the valve when you do. And you can have a new liner put in.
