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Worn Topend???...LOL. All must see.

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Ok, for the new guys and a good laugh for the residents. The boys 125 ran on its last leg today. Gotta watch the video

Video here

IMG_0005.jpg

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oh, BTW, the life on this topend is about 120hrs. Guesstimating based on it trans oil changes. its had about 14 changes and we change oil about 8-10 hrs of ride time.

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That's pretty funny, but why in the world did you run it (chance it) so long?

It still ran fine, just not alot of power. Truthfully, I don't fear anything. If it blows, it blows. But I've said for over 30 years and still stands true. "My motors don't blow".

It'll get torn down today, everything mic'd and gauged. If all it needs is a ring, then that's all it will get. Unfortunately, I think it's due a crank.

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120 hours on a piston! i dont even have to say it! that speaks for it self i dont even keep a bike for that many hours.

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Yeah, they are fine with 150+ hours on them.....putting around on the pilot jet. :ride::banana::ride:

Ok, you're up one. Paybacks are a B!tch. LOL:worthy:

120 hours on a piston! i dont even have to say it! that speaks for it self i dont even keep a bike for that many hours.

Guess you have a 4 stroke. CHeaper to sell it and buy another then rebuild one. HAHAHAHA

Got my smartass comment in too.:thumbsup:

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on a serious note i had 2s pistons disinagrate iinto pirces no bigger than a penny.

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It still ran fine, just not alot of power. Truthfully, I don't fear anything. If it blows, it blows. But I've said for over 30 years and still stands true. "My motors don't blow".

It'll get torn down today, everything mic'd and gauged. If all it needs is a ring, then that's all it will get. Unfortunately, I think it's due a crank.

Keep running it in such fine shape, and your statement won't hold true for much longer. :ride:

Do you REALLY think it only needs a ring?! :thumbsup:

Have you not seen enough pictures on the internet to be aware of stress related failures on parts that were dimensionally within spec?

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^ my 1992 rm 125 that bought new with ten hours was even worse. the biggest piece that came out was no bigger than a penny. i need everything head cylinder crank ,

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you could look at it another way,if the piston lasted 120 hours you know its a keeper!

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I use Vertex Pistons. Here's a few pics so far. I'm going to do a full pictorial on rebuilding this.

This is the topend using Amsoil Dominator. I'm happy with it.

120hrsusingAmsoil.jpg

This is the piston that will be replaced. Apparently a small piece of casting from near the PV came off. It looks worse than it is. It's a slight scuff.

scoredpiston.jpg

insidecylinder.jpg

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Keep running it in such fine shape, and your statement won't hold true for much longer.

After building many different motors in my life I've only ever had one lock up. But it wasn't my fault. The YZ 80 I had just rebuilt was ridden by him and his 240lbs dad together running 4th pinned up the street. I told them I build badass motors but not an 80 than can hold 400lbs wide open. :thumbsup:

Guess I've just been lucky so far. hopefully My run of good luck continues. I can't afford too many blown up motors.

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i started using vertex in my 4s they do look good after 50 hours but replace anyway you never know when they will let go. i replace rings at 25.

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