Two stroke won't start

DeadSmoke · L Plate Warrior Joined: 13 Feb 2012 Karma :

I just picked up an Aprilia RS50 on Wednesday. It's a 2003. I took it out on a short ten mile ride when I got back Wednesday night and it did fine. Thursday I went to take it on another ten mile ride to meet my girlfriend for lunch and about eight miles in it stalled out while I was going down the road. Started up again and when I went to take off it failed to accelerate at all, and then died again.

I'll admit I don't know much about mechanics, and I've only really done so much with the bike seeing if I can figure out what's wrong with it/fix it without taking things apart.

The bike will start if you bump start it (push it in gear, let the clutch out) but it won't stay started for long and won't accelerate, and does this regardless of the position of the choke. If you turn the accelerator while trying to start it, the carburetor produces a sort of popping sound. Very low and pops every time the engine tries to cycle. Took the spark plug out and it's black sootie looking, and as far as I know it's supposed to be a creamy brown colour. The guy I bought it from said he jetted the carb himself, but I don't know how much of a difference that makes.

Any ideas?

DeadSmoke · L Plate Warrior Joined: 13 Feb 2012 Karma :

I just tried something that I read, and that was bumping it in second gear and then slowly accelerating.
When I did that, it just made that same low popping sound.

_Iain_ · Banned Joined: 01 Feb 2012 Karma :

Did you run it low on fuel? Could be something blocked in the carb.

Did you run it low on oil? Could be very much fucked internally if so!

Rough guess, it'll be expensive and probbably warrant an engine rebuild. Seems to be the conclusion when someones RS breaks down then wont start back up/run propperly Laughing

I'd have walked away the second he said he'd jetted it himself. Messing about with the air fuel mix without propperly knowing what you're doing is a one way ticket to a fucked engine. A bike thats known to be a bit highly strung combined with backyard engineering of questionable standard just isnt a good combo!
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_Iain_ · Banned Joined: 01 Feb 2012 Karma :

Double post. I hate my computer.
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Please be aware that the above post may be full of complete nonsense.
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DeadSmoke · L Plate Warrior Joined: 13 Feb 2012 Karma :

Well, he hadn't said he jetted it himself until after I was home and the issue first came up.

It wasn't run on low fuel or low oil, the ratio's where it's supposed to be. The guy raced it and is a mechanic, or so he says.

_Iain_ · Banned Joined: 01 Feb 2012 Karma :

He raced it with numberplates & lights? Confused

More to the point, you bought a bike for the road thats supposedly been raced? That would prove that it's DEFINATELY been thrashed! Laughing

Be interested in hearing whereabouts you can race a roadgoing RS50 though - sounds like a proper good laugh if it's even been done.

A mate of mine claims to be a mechanic. He's even got the NVQ level 3 to prove it. However he couldnt suss out how to change a gearbox, how to reassemble a drum brake, how to replace a wheel bearing, or that the reason his car wasnt starting was due to it missing the coil lead...says a lot for "qualified" mechanics. Imagine if that was the level one course?

If they say theyre a mechanic who did they work for, when, how many years...check the backstory a little. If they say it was raced, what class, what team, what tracks, what results? Then make your excuses "ive just got to go get the money" and nip home and check up on it.

Methinks someones sold you a fucked RS50, probbably for a fair bit of dollah and made you look foolish Neutral

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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

DeadSmoke · L Plate Warrior Joined: 13 Feb 2012 Karma :

I'm assuming it wasn't professionally raced. More like he took it to the track and raced it, I would guess. I'm in the states, which is where he's owned it and raced it.

He's been really helpful about it, which would be strange for someone who sold it knowing it was fucked. I just got off the phone with him and he's been telling me things to try that could've caused the issue.

Says he jetted it up to 100. Not sure what that means other than rich on the air to fuel, don't know if it's considered good or bad for the bike.

_Iain_ · Banned Joined: 01 Feb 2012 Karma :

My bad, over here im not aware of any race class whereby you can run a 50cc bike, let alone a small CC trackday!

Regarding the jetting i couldnt comment for the US. I'd say to research some aprillia forums in the states and see whats what, as you've got different weather, altitudes, fuel, and a whole host of other bits and pieces.

Check if its got fuel & spark, if the answer to both is yes compression test. If compressions shite it'll need a rebuild.
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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

DeadSmoke · L Plate Warrior Joined: 13 Feb 2012 Karma :

Thanks Iain, That'll be my next route to take. Learned today that the gas is on the old side of the fence, so I'm going to drain and clean the carb really well and drain the tank just to see if that helps.

st3v3 · Super Spammer Joined: 16 Oct 2006 Karma :

It's time for a rebuild, I've just done exactly same to my 125. Crying or Very sad

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