Peugeot Speedfight problems

[mark_m]

My son has using this ped all year, standard (from what we know) Speedfight WRC 50cc AC and it has always been fine.

However he came home on it at the weekend and said it started to lose power and wouldn't run beyond 20mph (it can normally hit 40-45mph).

I tried it and it runs okay at first, gets up to speed, but after a few minutes started with the same fault with the power loss and then wouldn't run beyond about 25mph.

Haven't a clue what it could be, please help!!

[_Iain_]

What sort of age/mileage is it?

Checked the basics? In the past I'd check that fuel filter's not got an obvious blockage, that it pisses loads of fuel out when you suck on the vaccum feed to the tap, spark plug is a fairly healthy colour?

When it looses power, does the engine still sound perfectly fine or does the sound change or anything like that?

Does it run perfectly well i.e hitting 45mph and then slow down?

Is it only from cold that it works propperly?
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Please be aware that the above post may be full of complete nonsense.
Riding: '07 KTM Duke II, Baotian BT49QT-20 Driving: '88 Volvo 340

[mark_m]

Thanks for the reply.

It is on an 08 plate with less than 10,000km on the clock.

With regard to the fuel, it doesn't have a tap (at least I don't think so). The tank is full.

The engine does seem to sound okay albeit a bit 'breathless'.

When I tried it from a cold it ran okay and got up to speed then the fault started happening after about five minutes when the engine was warm.

[_Iain_]

Peds are really iffy about fuelling.

https://www.pedparts.co.uk/blog/automatic-choke-unit-50cc-mopeds

Check that out - if the chokes not disengaging then it could go stupidly rich and cause running issues when the engine warms up.

Fuel tap looks like this;

https://i.ebayimg.com/00/s/MzgyWDU3MQ==/$T2eC16FHJIgFHSOblERGBR6wq,69og~~60_57.JPG

Vaccum operated & sits on the bottom of the tank. When engine spins over it creates vaccum on the diaphragm which opens the tap to allow fuel to flow. If you disconnect both hoses, then suck on the hose at the bottom then fuel ought to pour out of the other one, it should also stop when you stop sucking on that hose.

https://imagizer.imageshack.us/v2/300x200q90/217/fueltapis7.png
____________________
Please be aware that the above post may be full of complete nonsense.
Riding: '07 KTM Duke II, Baotian BT49QT-20 Driving: '88 Volvo 340

[Andy_Pagin]

[mark_m]

[mark_m]

[_Iain_]

If it was to be a variator/belt/clutch fault I reckon it'd show itself straight away - the transmission doesn't really develop enough heat to make that much of a massive differnce straight off.

Exhaust blockage is a possible cause too, however it would reduce power all the time - the bike wouldn't run fine for five minuites and then go back to doing 20mph.

[andys675]

check the fuel cap breather, if it's blocked the bike will run fine for a while until a vacuum builds up in the tank and the fuel stops flowing.

good test of this is when the problem surfaces remove the fuel cap and you'll hear a whoosh of air as the pressure inside the tank equalizes with outside
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[mark_m]

We have took most of the bike apart and cleaned filters, auto choke etc and the problem is now worse; the bike won't hit 20mph, gets gradually slower then won't tick over and dies.

HELP!

PS should the lights on this bike work without it running? It behaves like old 6v electrics.

[evoboy]

[BMWilliams]

Run it until it starts to lose power then check the spark plug colour...
sounds like the choke stuck on or not working properly, causing it to run rich when it warms up, but on the other hand the mixture could be running slightly lean causing it to overheat and soft seize, either way if all hoses and blockages have been checked and ruled out then the mixture and choke need to be checked

Good luck
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