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  1. #1

    Replacing a piston. First timer. Pictures

    Hi guys. 2003 ultra 150 with around 100hours. I had some clogged cooling line issues that lead to an overheating. did a compression test after and got 120,120, & 60. Pulled the head to inspect the low cylinder and found it partially melted. Check out the photos. Lovely

    This is my first time getting into the top end and I had some questions. I inspected the jug and luckily it seems in damn good shape? I ran my fingernails all around in it and can't feel any rough areas. That being said I was planning to reuse it. Thoughts on this? Is it ok to do that or will it cause headaches very soon?

    I ordered a new 80mm wiseco piston kit and was going to drop it in. I was wondering since I'm this far in, should I also replace the rings on the other two cylinders? It's got around 100hrs and good compression and I'm probably just going to let it go but wanted a second opinion. How long are rings typically good for?

    Any input is much appreciated. Thx
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  2. #2
    We cant see the walls on the actual cylinder in question.

    One thing I wouldn't do is is mix match forged vs cast pistons. Since you have it apart it should be getting a complete top end including pistons and rings. Do it once and do it right!

    Change all the oil and fuel lines and invest in a tripple pisser kit, could have saved you from this mess.

    Good luck

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  4. #3
    steve45's Avatar
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    I wouldn't mix piston brands, they might be different weights and cause imbalance/vibration.

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  6. #4

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    Fun stuff, I'm a first timer also doing a rebuild, I had trouble finding the wiseco kit. Where did you get it?

    I talked to skiworx and they used wsm In 1's and then OEM on the stage 2's, so i figured for me the OEM would be sufficient.

    Someone on here probably could inform you better but from what I understand initial break-in with the forged pistons is crutial. The initial piston heat cycles need to be gentle as the piston expansion may be greater at first and the cool water prevents rapid cylinder expansion exacerbating the problem.Wiseco knows best so I'd talk to them.

    Good luck!

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  8. #5
    Damn I'm glad I posted up in here. Greenhulk forum saves the day again. Thanks guys! I really appreciate it.

    I was so wrapped up in getting the top end torn down and getting parts on order to salvage some riding time this summer, I didn't even stop to think about forged vs. cast and aftermarket vs. oem. I'm sure the difference in material, weight, and rotating mass would only do bad things...

    I cancelled my order for the wiseco and i'm gonna go OEM instead.

  9. #6
    xxx2's Avatar
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    Cant see cylinder but if you can't hang a nail on any scratches, run a hone through it to get a good cross hatch for the new piston/rings. It will be fine using 1 weisco and leaving the rest stock just make sure to measure your cylinder to wall clearance...from memory I think a .004 feeler guage should hold the piston in the bore without dropping but The piston should come with a data sheet from weisco for clearances/ring gap. Also you need to find the reason you melted a piston.

  10. #7
    He did clogged cooling line. Which shows you how important a tripple pisser kit is.

    I have had very good luck with wsm pistons. Oem is top quality tho

  11. #8

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    Yeah, I'm not saying the Wiseco is bad, just things to consider.

  12. #9
    xxx2's Avatar
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    Oem is going to be best due to the higher silicon content used during casting, but most replacement pistons will suffice as long as they are set up correctly. I completely missed the part where you said clogged pisser.

  13. #10
    steve45's Avatar
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    Quote Originally Posted by xxx2 View Post
    run a hone through it to get a good cross hatch for the new piston/rings.
    Do not do this! These cylinders are nikasil plated. Clean with muriatic acid and rinse thoroughly. If you feel you must hone, just do it very lightly, just a couple of passes.

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