ebay HT bicycle engine teardown after 3k or so miles:
Finally took the old Pig bullet apart today.
News was not good.
Found LOTS of scoring on the piston and cylinder wall caused by flaking chrome in the bottom of the jug. Both rings were pinched and stuck from galling.
Also had excessive play in the small end of the conrod. The pin and bearing looked fine, but the small end of the rod had worn to the point of allowing the piston to kiss the head and leave a ring in the carbon.
I KNEW there was something going from the change in the sound at cruising rpm.
It was starting to sound dangerous and scary when I replaced it, and now that I see the reason, I'm glad I did!
Everything else looked brand new, which surprised me as I was expecting some slop and grinding in the main bearings. But the bottom end looked great aside from the aforementioned con rod wear. The clutch looked good too.
I'm assuming the flaking was simply luck of the draw and my engine started life with defective plating as I ran my usual oil ratio the entire service life and have never seen this defect in any of my engines until this one.
Still, 3-3 1/2k miles ain't too bad for a $150 kit engine considering.
I'm saving the bottom end for parts since the mains and clutch are still in good shape. All the small parts are still useable too.
I may measure the current small end diameter and see if I can find a larger bearing to let me try using this bottom end again someday without rebuilding the crank (which I don't have the proper tools to do anyway)
Sometimes you're the windshield, sometimes you're the bug.
If more is better, then too much is just enough.
If you can't afford it, build it yourself.
Last edited by maniac57; 01-15-2014 at 11:22 PM.