Engine Trouble clank clank sound all the sudden and then some

Discussion in '2-Stroke Engines' started by dotcom, Jan 22, 2015.

  1. dotcom

    dotcom Member

    20150122_203224.jpg 20150122_203128.jpg 20150122_203201.jpg all of sudden bike motor stops at working at about 30mph and its goes clank clank until bike slows to a stop. It was sounding like the piston was hitting head so i thought maybe blown head gasket but I just removed the head and there is a score on cylinder wall plus some scoring randomly in different spots on top of piston, and on the bottom side of the head. please help.
    is it the rings that caused this? and what is needed to get going again?

    update with new photos. rings are not broken but wrist pin bearing has one broken bearing part of which half is missing, i think inside the engine which is what caused all of this scoring. would it be ok to still use all parts and just replace the broken part? or since there is a score in the cylinder wall, will that have to be replaced too? how about the head with all the gouges? please help

    Attached Files:

    Last edited: Jan 22, 2015

  2. butre

    butre Well-Known Member

    looks like that roller broke in half and got sucked through the transfers. you might get away with just a new top end (cylinder, rings, piston, wrist pin, and bearing) for about $40 but to be safe I'd just replace the whole engine.

    unfortunately, you wrecked that fred head pretty badly too. if it were me I'd put that thing on a lathe and cut a new squish band. you could ride on it, but it'll do nasty things to your performance and probably create hot spots pretty quickly
  3. dotcom

    dotcom Member

    is it safely possible to still use the cylinder with it scored?
    also where could i find a lathe for this locally?
  4. HeadSmess

    HeadSmess Well-Known Member

    cylinder...write it off. piston and bearing, obviously the same.

    chances of crud being in main bearings...high.

    id keep the head and thats about it...

    find a model engineers society...old guys with hobbies accept currency of beer. businesses try and wring your wallet dry...
  5. dougsr.874

    dougsr.874 Active Member

    Chances are some of the rollers from the bearing went down inside the engine...unless you completely disassemble the engine you're chancing the same thing happening again...my advice is to get another engine....not worth the trouble
  6. dotcom

    dotcom Member

    glad I have another but this bottom end is new so I will likely look for the broken roller. Ive already switched engines and ran the same one after changing the cylinder and piston and it seem ok but i did feel a difference. I still have to replace some components before the second bike will function. Since these are not Honda, I keep a back up
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