Posted by: scootswla | 10November'09

Exploritory Surgery


During a recent expedition my People 150 failed to make it home under its own power. Lets take a closer look at what happened.
Failed is maybe the wrong word to use, as if the kymco some how failed me, in fact it was the other way round. I suspect that I had let the oil level get to low, that combined with an all day, all out, full throttle excursion and end up with a murdered scooter. The first step in the autopsy was to remove the seat then the body panels.striped

Next I removed the exhaust and disconnected the carberator and any hoses and wires that connect the engine to the frame. Unbolting the rear shocks and pulling the swing arm bolt I dropped the engine from the frame so that It would be easier to get around.

Four bolts remove the head cover then four more remove the head. I forgot to take a photo of this step but the head is where your cam shaft and valves are. This is a drawing from a manual but its way less complicated than this looks, otherwise I wouldn’t have taken it apart.Head Picture

Once the head was off I started to see the first glittery bits of mechanical death.


The flakes you see on my finger tips are aluminum, and there should not be any extra aluminum knocking about the combustion chamber. Removal of the cylinder let me know for sure where these flakes came from.PistonBad News

It doesn’t take a scooter mechanic to know that’s bad news with a capital bad.damage

The irregular shape circled above is damaged caused by the crankshaft when the piston was at bottom dead center (BDC), when the piston is closest to the crankshaft. Because the top of the piston skirt was broken the piston didn’t stay straight in the cylinder, struck the crank, and locked up tight.

So now the question is “will this story have a happy ending?

I’ve asked around a little and have been told that this is a GY6 engine. Thats good news because the GY6 is a Honda design that has been cloned and is found in almost all Asian scooters. There are tons of parts available from third parties for GY6 engines. Before I start ordering parts though, I need to open the crankcase and make sure there are no metal bits or other ugly surprises waiting inside. To open the crankcase you have to remove the flywheel, and that takes a special tool, which I ordered today. Stay tuned and I’ll continue to share what I find and the progress made.

Remember before you’r next ride, do a pre-ride inspection. Oil level, air pressure, tire tread, brakes etcetera. You’ll be glad you did!



  1. Wow, Paul, that looks major!
    Any plans to put a BBK in it, just in time??


  2. Paul, I re-read your article and I just have one more question:

    Did it come with a pre-warning? If so, could you retrace back to that point?


  3. L you really know me, of course when I put a new top end on it will be a little higher displacement. They make everything from a 155 to a 190? I think, most likely I’ll go somewhere around 170cc. As far as a warning goes I should have checked my oil before leaving the house and maybe again at lunch because I was riding so hard. The bike simply lost power , and quickly, when it failed . It didn’t lock up till I tried to restart it.

  4. So Paul, in your opinion, if you had realized just in time what was lacking and added oil after you just lost power, would that be enough to save the cylinder, or otherwise…?


  5. No, I think it was already toast, just not locked up yet. I think I lost power because I lost compression because the piston started to break apart. All those times people said “that’s a lot of oil on your cases” I probably should have seen if any was left IN the cases.

  6. You’re right on the money!
    Right? It’s gotta come from somewhere (all that oil)?
    Costly for you; but a valuable lesson for all.
    Thanks, Paul!
    Resurrect the Kymco!


  7. […] the saga of my Kymco People 150 rebuild, here’s a little update. (if you haven’t look Here and […]

  8. […] back in December of last year I started rebuilding my Kymco People 150. (Catch up here, here and here) I installed a NCY big bore kit but a few snags came up and with plenty of Vespas to […]

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