<![CDATA[How long does a piston last, really?]]>My 2002 DE03 DTR has gone 45000 km, supposedly on the first piston and rings according to the former owner.

Sure, it was restricted for 21 years, and wear is quite exponential to load - but still... I would expect the bike to be on its third piston or some such by now. I have had DT's seize on me at full tilt before, so I was under the impression that a piston and rings do not really live more than like 15000 km or so?

But when I put the endoscope in the exhaust port of this one, it looked fine. Had horizontal lines on the cylinder, even.

]]>https://dt125r.co.uk/topic/3250/how-long-does-a-piston-last-reallyRSS for NodeMon, 17 Aug 2026 23:35:08 GMTSat, 16 Mar 2024 20:12:37 GMT60<![CDATA[Reply to How long does a piston last, really? on Sun, 17 Mar 2024 18:09:00 GMT]]>Classic, well they say nothing last forever.

I'd change it at the recommend service interval, if nothing else, restores lost power.

Did you see my Cagiva Raptor. Nothing wrong with that engine on the face of it. Started on the button and ran really well. Last year I decided to do the service interval.

Turned out the piston had a hairline crack in on top of the piston crown and down the gudgeon locator...ticking time bomb.

I had a barrel replated, new piston/rings and the bike was utterly night and day in terms of performance. The thing absolutely flew.

Then a few weeks later it was really struggling to run. I went on an overseas trip and came back when the temperature had drops some, then the engine just died.

I haven't stripped it enough to figure it out yet, but at 30 PSI, prognosis is not good. I whipped the cylinder head off and the piston/bore are in good shape. My guess is the crankshaft seals have given up. The restored new power was just too much for them and they've let go.

Another one for another time

]]>https://dt125r.co.uk/post/31806https://dt125r.co.uk/post/31806Sun, 17 Mar 2024 18:09:00 GMT<![CDATA[Reply to How long does a piston last, really? on Sun, 17 Mar 2024 14:18:28 GMT]]>My DTR had 56000km's on original piston,it had still life in it.
With a fresh set of rings and a fresh honing it could go another 15000km's probably.
Still have it for measurment's and is usable.
Off topic I had a Piaggio Skipper 150 2T,with 95000km's on original piston with nicasil cylinder.

]]>https://dt125r.co.uk/post/31804https://dt125r.co.uk/post/31804Sun, 17 Mar 2024 14:18:28 GMT