Aprilia 125 knocking sound in the engine - Please help!

[Oh-liver]

Hello all

I was wondering is anyone could help we with my problem. I have just bought a 2004 aprilia rs 125, after having a 50 for a year. The 125 has only done 300 miles

The trouble is that whenever I rev the engine (even at operating temperature) I can hear this strange knocking sound coming from it. When you put your hand on the frame you can just feel the vibrations of the knockings. The knockings are more audible when closing the throttle after revving.

The bike also has trouble starting but when it does start it idles perfectly. I have already replaced the spark plug and checked all the oils which hasn't helped.

I have a friend who says that this may be due to the fuel not firing at the right time in tandum with the piston but he has no real technical expertise.

I have yet to give the bike a real ride as I have not passed my full motorcycle licence, i can only ride it on private land. I have started it a few times without using it which I know isn't that good for a two stroke.

I would very much appreciate any opinions that you could offer.

Ah and on a completely different topic I have to release the clutch a very long way (to the tip of my fingers) before the engine engages the wheels. Is this normal or does it need adjusting?

Many thanks,

Oliver

[Evo]

If your 17, your legal to ride it on L plates. Providing you are insured for the vehicle. Though being on the L plates, you are of course prohibited from motorway access.

Regarding clutch biting point. It depends on how tensioned the cable is to where the bite is. Play with the tensioner till you find best for you. Tensioner is a gold/bronze screw located on the handlebar/clutch lever mount. Basically the same idea as a push bike.
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Bikes owned
1989 VFR 400 RR NC30

[Oh-liver]

The bike is derestricted so I cannot ride it yet but thanks for the tip on the clutch. I'm glad I don't have to modify the clutch in the engine.

Thanks, Oliver

[Evo]

[numpty]

It could be that you're fuel is igniting before the piston reaches Top Dead Centre (as your mate said) or it could be a fucked bottom end. Do you know what sort of fuel you are currently using. Also what sort of 2 stroke oil?
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Current bike: CBR600F-Y

[element]

can you record the sound? could be piston slap? Those RS125's need alot of top end maintence if abused. Also I dont belive that bike has done only 300 miles either (its possible but if it had it should definatly not be making any noise at all if it was). My bike is an 04 and its done 10k which is about average mileage per year. I think RS's need a top end rebuild after 7k miles is it?

Your best bet considering your knowledge is probably taking it to a garage and bending over.. for example... £90 for an RS piston... £30 for my DT
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04' DT125RE (run-a-bout) // 89' DT125R (rebuilt + supermoto conversion)
SPARES FOR SALE. 2RK TZR // 82 DR125 // DT125R/E .... PM ME...

[Oh-liver]

I have no idea what fuel or two stroke is in the bike as I have not needed to fill them up yet.

The bike looks spotless so it it seems unlikely that it has done more than the mile counter says, but hey, anythings possible.

I have a haynes workshop manuel so of course I am an expert!

I guess my best bet is to give the bike a fast ride (when I can) and hope that its solves itself. Otherwise I will have to go to a mechanic and take it.

Anyway thanks for all your help people, appreciate.

Oliver

[Kickstart]

Hi

Sounds like a low mileage for the age.

While it is possible that it is ancient fuel that now has an octane rating barely into double digits it is probably unlikely.

Normally a knocking sound is the sign of a wrecked big end bearing.

All the best

Keith
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