Hello all, just thought I'd post this as it was a bastard of a problem.
Daughter got a piece of crap 50 CC scooter.
Bike was being a real bastard, really hard to start off the starter motor, would just wind and wind and not fire. would start of first or secod kick start (but daughter is a wuss and couldn't kick start it, let alone get it on the main stand)I had changed the battery at about six months old so I thought it might have low cranking voltage (not enough juice for the coil), jumpered it with car battery,, no joy.
Pulled the spark plug out, checked spark, looked OK'ish (but then again no compression (load) from engine without a spark plug, so I decided to take the coil off my Viffer (which im welding the exhaust on, another long story((TOP PIPE UNDER ENGINE CRACKED->TAKE ENGINE OUT< BOO HOO), tried coil, still same problem.
Moved on to carburetor (why not) Stripped it, cleaned it (TOTALLY), refitted it, same problem.
GRRRR.
Found the problem tonight, there was NO valve clearances, [LIKE NONE], gave them 400 whatevers of an inch and the bike starts first time off the starter motor (now that's just fucking ODD HUH).
Anyway, the daughters happy, think I might get her to sell it and buy a Honda (before she swipes my viffer)
A COUPLE OF NOTES FOR THE HOME MECHANIC::::::
IMPORTANT: do something with the front wheel disc bolts/nuts, my daughters one had ni-locks on it, one came off and the bolt jammed between the disc and the caliper (luckily she was just taking off from an intersection). I mig welded the little buggers on. but you might want to fit spring washers or something ( I have a MIG handy if your in MT Roskill. :-)
The choke is some sort of bi-metallic thing, it gets power from two wires in, 12 Volt AC (YES AC) must get it from before the rectifier, then it gets warm and pulls the needle valve out (I think).
Definitely change the spark plug, It had a Chinese A7RTC, I used a NGK CR7HS, but you could use a Champion RZ10YC.(Performs better with new spark plug)
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