150cc GY6 engine starter defeated by engine compression

[randscaping]

Hey all, this will be my first post in a scooter forum so I'm anxious to see how awesome the fellas on this site really are !

So I have one of the VIP scooters (TaoTao I think?) that I have been trying to get it running reliably since I took it off the hands of its previous owner who drove it daily. It is a 150cc GY6 engine

The problem I'm running into is, it won't smoothly crank. I presumed it was the starter, so I got a new one off my fave stock parts site, (vmcchineseparts.com, if anyone wonders) and it made zero difference. I get the best cranking attempt by the engine when bridging the posts on the starter solenoid. The engine does turn but only as far as compressing the fuel-air mix in the cylinder. Before this happened, the engine would get past this point but only to make an awful grinding noise from the area where the starter gear meets the "flywheel". When looking at the cooling fan while it was making this racket, it looked like the starter would turn the engine to a point (resistance from achieving compression) then "bouncing away" (rotating backwards with the starter still engaged) and being pushed right back to that point by the still engaged starter. (that's why I faulted the starter).

So it is perfectly logical to think, "well, common sense tells you that if it's doing that, you're not getting enough power from the battery!" However, this is occurring even when I have a fully charged battery on the scooter, AND hooked up to jumper cables to a running 1998 Dodge minivan.

What I recently did to this scooter besides replace starter:
-new keyed ignition cylinder
-new CDI box
-new NGK spark plug
-new ignition coil and lead wires
-new engine cutoff/ignition button/throttle assembly
-new 9Ah scooter battery
-new intake/exhaust manifold(studs broke off old exhaust port), Scooter has run and drove since this was done, so we know the timing, valves and intake seal are good.

-new carburetor w/auto-enricher.

All Parts Replaced are stock and rated for the 150CC gy6.

So, with that being said, maybe one of you awesome readers/responders knows that this was posted before and resolved already. If this is the case, I have no problem following a simple link to that thread, even if that is the only content of the reply.

Thanks in advance for everything guys, http://www.scootdawg.net/images/smilies/thx2.gif can't wait to get this thing on the road! http://www.scootdawg.net/images/smil..._scooter_2.gif

P.S. If it makes any difference, the last time the scooter was running and driving, it sputtered and stalled while I was riding downhill on it and it has not fired up since, even if only to die half a second later.