Bike stopped, will not start again??

Hi, I got my new pride and joy (mini dirt bike 49cc) about a week ago and rode it for the first time last night, went fine, brought it home and everything was sweet. Today i took my bike out again, started it up rode around for about 10 mins, stopped it for about 5 mins and then started it again. I then rode it around for about another 10 mins but it felt less powerful and wouldn't rev as good as before, then it started to misfire and cut out. I checked the fuel but theres heaps in the tank and lines. I tried to start the bike up again but it wouldn't with choke on or off. I let it cool down for about 20 minutes and tried to start again but it still wouldn't go. I then took it home and changed spark plugs but still no go. Is this an electrical problem? advice would be greatly appreciated.

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49cc Mini dirt bike
Advanced timing key
HP Pod filter
Fiberglass Reeds (ADA Racing)
NGK BPM7A
2 Spring Racing Clutch
Racing fuel filter + line
HP Racing exhaust
High tensile bolt kit
NTN C3 Rated wheel bearings

maybe electrical or maybe carb blockage. to eliminate the electrical fault try this, remove the sparkplug from engine put the plug wire back on the sparkplug then touch the side of the plug to any part of the engine and give the engine a pull start, look closely for some spark coming from the low end of this plug, [if you don,t hold the rubber end cap you may get a shock] if no signs of spark its either the sparkplug, or the retainer clip which is on the end of the plug lead not making contact with the lead or your coil has come loose from adjustment to flywheel or your coil is stuffed [ which does happen often] with chinese parts. i will always say clean out your fuel tank, replace the crap fuel filter and fuel line. say you have spark then your problem is the carby, you have crap in the carby and it must be cleaned out, the carb must be removed and striped down so all jet holes are free or debree. no spark no go. no fuel no go. find out what has no go first.

thanks RD, I will try to see about spark now, I don't think it would be the carby as I took your advice and flushed tank and replaced lines + filter before I started the bike. I put a timing key in, do think its possible somethings happening as a result of this, e.g flywheel is not on properly or magnets are covered in something? anyway, I will check all this now (before I didn't know where to start looking, but now It should be sweet)

__________________
49cc Mini dirt bike
Advanced timing key
HP Pod filter
Fiberglass Reeds (ADA Racing)
NGK BPM7A
2 Spring Racing Clutch
Racing fuel filter + line
HP Racing exhaust
High tensile bolt kit
NTN C3 Rated wheel bearings

you mentioned the timing key, make sure your flywheel centre bolt is still tight, maybe it has come loose and the flywheel has come out slightly causing wobble / alignment and no pick up to coil.

SUCCESS!!! I had a look at the spark plug and then followed the lead and found something strange. The killswitch lead had jammed between the fins of the head and melted. The two wires must have been touching, I pulled the lead off and cut off the damaged bit and soldered it back together and tried to start my bike, it started 2nd pull sooo happpy
Thanks for your help RD, I was getting worried as I have a big weekend of riding planned and if my bike wasn't going I would have been spewing!!

__________________
49cc Mini dirt bike
Advanced timing key
HP Pod filter
Fiberglass Reeds (ADA Racing)
NGK BPM7A
2 Spring Racing Clutch
Racing fuel filter + line
HP Racing exhaust
High tensile bolt kit
NTN C3 Rated wheel bearings