PX 125 Bogging down problem

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parky
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Wed Oct 28, 2020 3:58 pm

Hi, Having problems with my PX 125 bogging down. As soon as I turn the the throttle the revs just disappear, if I am lucky I can just catch it before the engine stalls and by twisting the throttle again it picks up and runs ok. I have cleaned the carb within an inch of it's life and the scoot runs fine on tick over. I have also disconnected the fuel pipe and fitted up a temporary petrol tank to isolate the existing fuel tank as I thought there might have been a problem with the fuel supply but still the problem continues. Any further ideas would be welcome as I am now completely stumped ?

l111amo
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Main scooter: Gp186
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Wed Oct 28, 2020 7:43 pm

From memory isn’t there a jet hidden away underneath, think it gives this fault

Andy Beard
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Wed Oct 28, 2020 8:36 pm

My first thought was maybe a dicky float/needle + take the idle jet & main jet stack out, give them & the passageways a good clean with carb cleaner!

Good Luck Parky!

gaz_powell
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Sat Oct 31, 2020 3:06 pm

Worn out carb.... Had exactley the same on a T5.
Tried everything as I could nt believe it could be the carb after sonic cleaning etc.

Borrowed a carb as I was stumped and bingo.

parky
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Sun Nov 01, 2020 2:30 pm

Thanks, looks like it might have to be a new carb after all, I was hoping I wouldn't have to purchase one and then find the fault was something else, but as the carb has been cleaned with carb cleaner and also had a blow through with an air line I might have to bite the bullet and dig deep. I have been thinking about tucking the scoot away for the winter, if I do, what is the best way to store the scoot for a few months?

paul d
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Main scooter: T5 172 Tv 240
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Mon Nov 02, 2020 1:34 am

You could recheck and reset your mix screw. Simple check and it'll only cost you time. The mix screw is located at the back of the carb box and is accessable from the outside. Either a long screwdriver or a 7 or 8mm socket with an extension will get you past the shock spring and get you working. Start the bike and warm it up. Then while the bike is ticking over, turn the screw a quarter at a time stopping and listening to the engine. You want the setting where the engine revs climb with each quarter, the drop with the last turn. Go back a quarter to where the revs are highest, then set your tickover to where you like it. Tickover screw sticks out of the top of the carb box. As with anything on a carb, don't tighten in the mix screw with force. I bet it'll make a difference. Good luck with it!

gaz_powell
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Mon Nov 02, 2020 10:23 pm

Perhaps I should have caveated my response. The carb change came after cleaning the carb, checking mixture, new float needle more cleaning
Then went into electrical side with no joy, coming back to carb.

parky
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Thu Nov 05, 2020 3:33 pm

Thanks for the responses I will keep persevering and if no joy will put the scoot away for the winter and try again in the spring. Luckily it is
not needed for daily transport.

parky
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Thu Nov 12, 2020 2:24 pm

Thanks Paul d for the advice, I have tried re-setting mixture screw and the tickover and there is now a vast improvement. I am yet to do a plug chop but hopefully all will be ok with that.

However as the scoot has been laid up for quite a few months I am now finding a problem with the gear change.. Previously the gear change has been as slick as a brylcream salesman and a joy to use, but now it is very stiff and difficult. As you can tell I am no mechanical expert so any advice would be gratefully received.

paul d
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Joined: Thu Jun 30, 2011 10:00 am
Main scooter: T5 172 Tv 240
Location: Galway Ireland
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Sun Nov 15, 2020 3:58 am

I'd say your gearchange issue is just a lubrication thing or a clutch cable that needs tightening. The clutch is adjusted under the engine and is obvious when you see it. If the bike is creeping forwards when the clutch is pulled then the cable needs to be adjusted and thats your gearchange issue. Any strands broken at the lever or underneath means it has to be replaced. For the gear change mechanism the easiest place to start is the selector box on the side of the engine below the fan. There's a cover held on with one screw. Undo the screw, take off the cover and grease the wheel that has grooves, a spring, pin and 2 gear cables attached to it. Also you can inspect the condition of the cables. Any fraying or loose strands means the cable has to be changed. If your gearchange is still difficult then remove the handlebar top. Undo the 4 screws on the underside of the handle bar, then push your speedo cable into the fork which will allow the top to rise enough so you can unwind the speedo cable nut under the speedo, unplug the block carrying the wiring, then set the top aside. If its a newer model remove the mirrors. Inspect the condition of the cables. Any fraying or loose strands means replacement. Grease the gear tube and anywhere there's friction. Drip some 2 stroke oil into the cables if you can. If none of the above works then I'd change the oil. Best of luck with it!

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