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Dec 19, 2021 23:11:13 GMT
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Have we got any scooter experts on here? I haven't had much success with scooter forums or Facebook pages. My 16 year old son has got a 2003 Vespa et2 scooter. It's a little 50cc 2 stroke twist and go, which is a lot of fun when it works. It will start up and idle fine but when you give it any throttle it bogs down and dies. The spark plug looked whitish so I suspected an air leak. So far I have fitted a new spark plug, carburettor, inlet manifold, Reed block, air filter and new variator rollers. It also has a new exhaust with the restrictor removed. When we first got it I fitted a new battery, stator and coil to get it running. I've done a compression test and that was fine. I've got a box full of jets but it doesn't seem to make any difference. I'm completely baffled by this. Any suggestions before I give up on it?
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67 VW Split bus 69 Beetle Cab 96 Jeep Cherokee XJ Sport
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Fuel tap thingy that pushes into the bottom of the fuel tank, if that goes it will only tick over and if you try to rev it just dies
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Dec 20, 2021 10:28:47 GMT
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Sorry I forgot to mention that I have replaced that too, twice! First with a cheap one, then with a genuine Piaggio part.
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67 VW Split bus 69 Beetle Cab 96 Jeep Cherokee XJ Sport
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awoo
Posted a lot
Posts: 1,503
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Dec 20, 2021 11:28:31 GMT
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its not over fuelling with a weak spark or some kind of mix of the two? an air leak will cause it to have rampant revs (my vespa px125 just reved to the red line when it had an air leak due to carb gasket getting soaked with fuel and failing)
surely its either not getting either enough air, fuel or a weak spark so would point at the carb or a blockage somewhere. or maybe a bubble of air in a fuel line?
my vespa is for sale btw if anyone is interested.
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Dec 20, 2021 13:10:12 GMT
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Well, it isn't over-revving as you describe or backfiring so I think that might rule out the air leak. I've tried spraying carb cleaner around all the joints when running too.
I'll try a new HT lead then maybe try to get hold of a different coil to make sure the spark is as good as it can be.
How much are you selling your 125 for and where are you based? My son is 17 in January so I am just thinking about going for another bike if I can't fix this one.
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67 VW Split bus 69 Beetle Cab 96 Jeep Cherokee XJ Sport
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awoo
Posted a lot
Posts: 1,503
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Dec 20, 2021 22:48:01 GMT
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I’m in Brighton, it is a 1983 and I restored it to a high standard in 2018. It will be around £2500. It’s got a 180cc barrel and piston but still 125cc on the v5. Even so it’s no performance bike!
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Dec 21, 2021 14:51:51 GMT
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Ah, OK, a bit out of our price range and the wrong end of the country. Thanks anyway.
Latest update is more experimenting with jets. The spark plug colour suggested a lean mixture so I threw in the biggest jet in the box, an 88. This actually brought about some improvement. At full throttle I can coax it up to about 20mph. It really sounds like it wants to go but is being held back somehow. The plug still isn't very dark so I'm going to try even bigger jets and see where that gets me.
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67 VW Split bus 69 Beetle Cab 96 Jeep Cherokee XJ Sport
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Dec 21, 2021 14:54:27 GMT
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Get him a proper bike restricted to 35kw when he's 17.
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93fxdl
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Posts: 2,000
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Dec 21, 2021 15:40:24 GMT
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Dangerous, getting your kids into bikes But the good thing is, they won't have any money for drink or drugs Ttfn Glenn But to be honest, a couple of those are mine
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Last Edit: Dec 21, 2021 15:41:42 GMT by 93fxdl
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Dec 21, 2021 23:01:05 GMT
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flyingphil
Posted a lot
Posts: 2,339
Member is Online
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Dec 22, 2021 21:53:35 GMT
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Just a thought.... is there a vacuum in the petrol tank? ie blocked breather ...? try with no petrol cap to test that possibility.
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Dec 23, 2021 10:23:26 GMT
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Just a thought.... is there a vacuum in the petrol tank? ie blocked breather ...? try with no petrol cap to test that possibility. Yes, I've tried that. It has a vacuum operated fuel tap which is flowing well, with good vacuum from the carb. I've ordered some new jets so when they arrive I'll try going richer and see if that theory is correct.
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67 VW Split bus 69 Beetle Cab 96 Jeep Cherokee XJ Sport
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Dec 23, 2021 18:59:55 GMT
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During tonight's tinkering I ran it up and down the road a bit. When I brought it back into the garage it felt like the back brake was stuck on. It doesn't do this when it's cold so I'm wondering if something is going on with the hub clutch or brake.
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67 VW Split bus 69 Beetle Cab 96 Jeep Cherokee XJ Sport
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Dec 23, 2021 19:40:35 GMT
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White plug on a 2 stroke is BAAD! Running very lean. Running lean will end up with it seizing. Is it pre-mix or pump supplied for the 2 stroke oil? You say you fitted a new de-restricted exhaust, have you re-jetted to compensate or did it say it will run from the box?
Bogging down is usually lack of fuel/ too much air.
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Last Edit: Dec 23, 2021 19:42:12 GMT by duggers
Needs a bigger hammer mate.......
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Dec 23, 2021 22:51:37 GMT
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It has a pump for the 2 stroke oil. When I bought the exhaust they told me it probably wouldn't need rejetting but I got a set of jets anyway and have been trying bigger ones. Looking at it tonight, the back brake was definitely seized, which won't be helping. Even with the brake freed off and disconnected the engine still won't rev cleanly. I'm really at a loss...
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67 VW Split bus 69 Beetle Cab 96 Jeep Cherokee XJ Sport
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93fxdl
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Dec 24, 2021 19:33:01 GMT
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A quick and easy way to test if it is running weak, run it on the stand open throttle wide, when it starts to bog down, squirt some carb cleaner down its throat, If it revs up that will identify your problem as lack of fuel Ttfn Glenn
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Dec 27, 2021 21:19:19 GMT
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I've dropped it off at a local classic bike specialist for a second opinion as I just can't make any sense of it. If it turns out to be too expensive to repair we'll cut our losses and trade up to another one.
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67 VW Split bus 69 Beetle Cab 96 Jeep Cherokee XJ Sport
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93fxdl
Posted a lot
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Posts: 2,000
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Dec 28, 2021 19:58:49 GMT
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I've dropped it off at a local classic bike specialist for a second opinion as I just can't make any sense of it. If it turns out to be too expensive to repair we'll cut our losses and trade up to another one. What was actually wrong with it?
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Dec 28, 2021 21:28:55 GMT
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I don't know yet, the garage lads aren't working this week. Hopefully I'll find out next week.
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67 VW Split bus 69 Beetle Cab 96 Jeep Cherokee XJ Sport
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