Diagnosis?

[Clutchy]

First off, the bike/ped : NRG liquid cooled 50cc if that helps


When going around 51mph at 10500 rpm ish (full throttle) it will suddenly 'bog' down to 9000 rpm and rapidly loose speed to 47mph even though its still on full throttle Its usually good for 55 mph but dont want to go near that speed (if even possible now) due to fear of damage. It hasn't lost any acceleration that ive noticed but it sounds a bit ropey now and then at 6000 rpm. (like when a 2 stroke starts up for the first time on a cold morning).

Servicing it tomorrow as im hoping its just the spark plug, doubt it though, any other suggestions? Belt and rollers are also being changed tomorrow as due.

Thanks a lot to anyone who replies, will be a load off my chest if I can at least guess whats wrong with it.
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Malaguti F12 Phantom-Dead, Suzuki AY50- Dead, NRG power DD LQ, CBR125.
*33 BHP restriction up on 10/12/14* Current bikes/car: SV 650 S/ MKIV GOLF
Guide to pass your test with no lessons!

[Clutchy]

hmmmmmmmmmmm?
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Malaguti F12 Phantom-Dead, Suzuki AY50- Dead, NRG power DD LQ, CBR125.
*33 BHP restriction up on 10/12/14* Current bikes/car: SV 650 S/ MKIV GOLF
Guide to pass your test with no lessons!

[Suntan Sid]

Possibles:-

Plugs have had it.
Carb needs cleaning.
Air filter needs renewing/cleaned.
It's not new any more.

Perm any 3 from 4!
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