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Post by freeqsee on Nov 24, 2019 8:04:42 GMT -5
Hi. I have a Piaggio Liberty 50CC 2T 1997. Recently I changed the carb(12mm) with a brand new one of 17.5mm. After that I went to a service and the mechanic blocked my oil pump cause I had some problems with the screw which goes into transmission. He blocked the oil pump to be always opened. I also changed the gas valve and the air filter with a new one. Now often when I go full throttle the engine dies and I don't understand why. Also, if I use throttle just 15-20% it works, but he wants to die. Can you have any ideas which can be the problem?
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Post by geoffh on Nov 24, 2019 9:15:03 GMT -5
I do not understand the oil pump set up as you describe it,can you explain again.your fuel problems stem from that larger carb and filter,go back to the 12mm and get it running properly,then try the larger carb with the same set up,take notes and only change 1 thing at a time ,open pod filters are hard to tune.keep us posted.
Geoff
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Post by Zino on Nov 24, 2019 9:15:18 GMT -5
You need to rejet the carb .
You made alot of changes bigger carb ,air filter and oil going full blast .
What carb type is it dellorto ,What main jet is in there ?
Do you have a range of main jets ?
Is it drowning in fuel or is it starving for fuel ?
What does you plug look like leaning dark or still light ?
Full throttle problems are 9 times out of 10 the main jet
Quick way to dial in main jet
Start by going richer first for safety and then go down a size till performance levels between 2 jets and default to the richer one (The larger jet).
Step one
If you have a range of jet go up 2 sizes based on your symptoms that should make performance alot worse .
Step Two
If performance is better keep going up sizes and until it start to get worse.
If performance is worse then go lower till it performs better .
After you dial in the main right to where it needs to be you might have to move the clip of the needle one notch up or down .
To dial in Mid throttle positions the needle is the main
Use the same method .
Dial the needle in to which one has the best response or if there are 2 positions that feel close take the richer one.
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Post by freeqsee on Nov 24, 2019 9:34:02 GMT -5
geoffh The air filter isn't a sport one or something. I just replaced the old one with a new one, same model, same size. The fuel valve is same as the air filter, just a new one, not a bigger one or something. And about the oil pump always blocked on ON, I asked the mech and he said that this will not affect the engine. I changed the 12mm carb cause because of it the scooter started too hard, over 20 tries. The new one is a no-name carb(it was the only one in stock), I just payed 20 euros for it and it is temporary cause I wanna tune the scooter in the future, 70cc piston, exhaust and 19-21mm carb. If I use this 17.5mm carb for a time without other mods, will it affect the engine?
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Post by freeqsee on Nov 24, 2019 9:38:18 GMT -5
geoffh About the oil pump: when I changed the carb, I broke the screw which goes into the transmission. Throught this screw goes the acceleration cable which open the oil pump. The mech asked me if I wanna change the entire acceleration cable or to block oil pump to stay always open. I asked him if an open pump will affect the engine, he said no, so I choose to block the oil pump on ON cause it was the fastest solution.
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Post by digitalrelay on Nov 24, 2019 10:24:17 GMT -5
You may want to temporarily remove the exhaust pipe to rule out a clogged muffler. I went through similar symptoms yesterday after struggling to get my scooter to even start. Once it did, the clogged muffler wouldn’t let me rev past 1/4 throttle. With the pipe off, the thing ripped.
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Post by geoffh on Nov 24, 2019 10:27:08 GMT -5
Sounds like your old 12mm carb needs some TLC,try cleaning it, all the passages inside need to be checked watch the how to vids in the tec section for help,these are fussy engines and need maintaince,if mine needs ore than one kick I start to worry.
Geoff
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Post by freeqsee on Nov 24, 2019 11:35:53 GMT -5
So I will clean the old carb. What about the oil pump? Is there a problem if it stays always opened?
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Post by aeroxbud on Nov 24, 2019 12:23:39 GMT -5
If it's like some of the other style cable pumps. You might get too much oil. They are designed to give a little at low speed. But more at higher throttle openings.
You could end up with a fouled plug.
You need to look at the plug and see what colour it is. A lot of carbs will come with a bigger jet than what you need on a standard 50cc.
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Post by freeqsee on Nov 24, 2019 13:43:35 GMT -5
Is it a problem if I use it like this for 10km? I will go with it at the service to remove that broken screw and let the oil pump to operate normally. Also, I will clean up the old carb and put it back on the scooter. Thank you so much for your help.
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Post by Zino on Nov 24, 2019 14:03:30 GMT -5
Pull your plug post a picture .
10 km could be enough to cook if you are getting to much oil and you are going lean .
On 2 strokes the right amount of fuel helps cool the engine too much fuel and you bog down too little fuel and you gasp and are starved and start getting hot real fast.
Oil on a 2 stroke is just for lubing it doesnt really help cooling it hurts since it gets in the way of having enough fuel.
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Post by freeqsee on Nov 25, 2019 2:58:04 GMT -5
 This is the plug. |
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Post by aeroxbud on Nov 25, 2019 6:05:13 GMT -5
Way too rich, or getting too much oil. What jet does the new carb come with?
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Post by freeqsee on Nov 25, 2019 6:12:17 GMT -5
I don't know what jet is. The carb is a no name one and it doesn't write anywhere what jets it has. I will look more closely and I hope I will find something.
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Post by freeqsee on Nov 25, 2019 6:33:11 GMT -5
I know for sure that it gets too much oil because of the always opened oil pump.
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