Throttle problem

FreeQSee

New Member
Drives
Piaggio
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?
 
Last edited:

Greg_PCRS

RMS Regular
Drives
BMW
U may have problems with the mixture. Check the spark plug if its too oily then the mixture is ng Shorten the plug and check the spark strength. Also, you may want to check if the carburetor is not too big and dosing too much fuel. Try to adjust the carb to suit your mixture. I had the same problem with my dads 50cc Kymco. Carb adjustment helped by it was 4T.....
Good luck

PS: can you explain what u mean by blocking the pump?
 

FreeQSee

New Member
Drives
Piaggio
The cabble which acts the oil pump has a screw. I broke that screw when I changed the carb and it is a bit complicated to remove it from the transmission's case. So, the mech asked me if I want to block the oil pump to be always opened. I accepted it and now my oil pump is always opened it not depends anymore by the throttle.
 

Greg_PCRS

RMS Regular
Drives
BMW
That might b an issue too....check the plug if its wet and black thats it. Unfortunatelly - as I wrote before - bigger carb may flood the cylinder it will b visible on the plug too as it should b wet (not excessively black) in this case, which points at fuel/air mixture ratio to rich...
 

Greg_PCRS

RMS Regular
Drives
BMW
should b brown and dry and clean, urs black and i can see black residue....oil i think too much fuel would leave it wet.
 

Greg_PCRS

RMS Regular
Drives
BMW
quite the opposite. If ur engine would have been getting enough air/fuel/oil mixture your plug should be brown i think in your case it is getting too much oil into the mixture. Fuel would leave only black stains/wet depends how much it pours into the chamber. I can see some black residue around the rim of the plug that's why I think oil. Besides, think - if It was ok before what has changed? What and who did what? I am not blaming your mechanic, but his modification despite his best intentions might have caused this.
 

FreeQSee

New Member
Drives
Piaggio
That was the cheapest and fastest solution. I will solve this too and the oil pump will run corectly.
 

Apis

RMS Regular
Location
NW
Drives
various
Is going from 12mm carb to 17.5mm not a pretty big jump? And the size of the jets will make a difference too. It could be that the main jet is too small, which is why she bogs down at higher revs.
Also, if the pump is always on it will probably delivering too much oil at low revs and also on the overrun when you slow down. This would start to gum things up.
Also, too much oil weakens the air/petrol ratio and the engine runs lean. Worst case....lean=too hot=hole in your piston.
 

Greg_PCRS

RMS Regular
Drives
BMW
Apis is right. spark combustion engine only may have 3 issues u HAVE to check before going any further. These things r: fuel air spark and (oil) in ur case.
Try to by pass the feed and mix oil i a jerry can according to manufacturers specs per full tank of ur bike. Put a new plug in and see if this will solve the problem.
 

FreeQSee

New Member
Drives
Piaggio
Yeah, I will clean up the old 12mm carb and put it back. Also, I will not use the scooter too much while the oil pump is always opened.
 
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