making rattling noise over 24mph

I have a Grubee star fire 48cc with 200 miles on it There's alot of vibration noises between 22mph
and 30 mph but at 28mph between 32mph it smoothed out A distinct rattling at 24mph between 28mph Maybe im pushing the engine to hard but it seems like it wants to go faster and i dont think ive maxed the rpm s I like to ride about 20 to 22mph im always looking out for the boyz though passed by a few{cops} here in phoenix and they just waved at me. the one distinct rattling noise is definetly coming from engine area cause i let off the gas and it stops should i be concerned with this i havent lubed or greased the gearing except put a dab of grease on the clutch end when installed . ty Chill Will AZ

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Chill Will Fear no Evil

Sounds like typical piston slap.
Sometimes....the motor mounts will loosen and it sounds like detonation. Check those.

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If it ain't broke, and you mess with it long enough, it will be.

check your nuts they might be loose. rubber between your mounts and frame might help with vibration.

One thing I've learned is that any rattle on the bike will sound like it's coming from the motor. Just saying.........

Mine does the exact same thing. It's the big clutch gear. Take off the right side clutch cover and put some (not alot) grease on the gear teeth. I use moly/graphite grease. I have readjusted the clutch several times and nothing stopped it. The greasing helps but I have about 1000 miles on my bike now and it's still there. If anyone has a real solution to this I'd really like to hear it. Is there any end play adjustment in the clutch shaft?

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Put something FUN between your legs..