I've been slaving over my brother's 77 super sport to get it ready for the bbq, and it ALMOST runs!

The thing won't run with the exhaust on (restriction in). We recently replaced the rings & compression is good, but it won't run with everything buttoned up. Barely runs with the SPARKPLUG PARTIALLY UNSCREWED or the exhaust unbolted. We've tried everything we know, and it's like the condensor is bad and the spark doesn't jump under full compression, only it was tested and works. We have done this with air cleaner on and off, prefers ON, but not much dif.

It pretty much fires but only when pedaling and doesn't sustain at all.

Previously this thing did the same thing but ran crappily due to a sheared and welded ring-since fixed. Any help is good.

We need this to run or we will be beaten after months of pain.

– zach


i guess you already checked to see that some part of the exhaust system is not plugged up with carbon?


You guys don't get it...

The moped gods have forsaken this machine. Moped Jesus was walking by and said "Arise my son, for this moped will never run."

I'm looking for those really really weird quirky problems. We've checked the carb, spark, compression, fuel flow, exhaust on and off, iair cleaner on and off, this is voodoo. We even have the electrical system pretty well isolated and it won't run. It all is for nothing though, since the back wheel came apart yesterday. Bad Juju.

Thanks anyway Joew and Nick. I appreciate it.

– zach

Re: You guys don't get it...

From what i've read, the weirdest problems come from electrical stuff, like a partially shorted magneto winding.. i dunno how to diagnose that.

im still curious about something. You mentioned "due to a sheared and welded ring".

Did a ring get caught and then.. weld itself to the cylinder?

It does seem like compression is an issue and you must think so too to have experimented with loosening the sparkplug. Cylinder or piston damage would be obvious.. i'm out of ideas..

like a nautilus

THe ring wrapped itself around the roll pin on the piston, then welded itself into a tiny little spiral. It was tinged blue and purple. Pretty cool really, except that it scored the cylinder quite a bit. It ran though. Now it won't, even though it has more compression.

It just won't run, even though everything is working individually. Maybe a magneto is shorting out. I had suspected something like that, even though the magnetos all look nice and shiny.

Re: like a nautilus

Jason Luther /

its probably a good thing it didnt run, since the WHEEL FELL OFF!!!!. sounds like a a fuel problem to me. same thing happens to my puch when i run out of gas, and i swear it has gas in it. -jason

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