changed the main jet and scooter no longer accelarates

[kopis]

hi everyone

I read through most of the topics and found some similar problems to mine however could not find anything that could help me.

I have upgraded from 82 to 84 size jet , which gave the scooter a bit more power.It run well for a couple days but suddenly it started choking as if it is starved of fuel....
It starts and idles ok, the trouble starts as soon as I hit the throttle, it stars choking again and there is little or no acceleration :/

Any ideas please?

I am a wannabe mechanic

[streido]

82 jet is normally perfect unless you fit an open filter, 84 may be too big for it. You wouldnt get any more power just from changing jets to a larger size anyway.

I would stick in a 82 jet and see if that solves it, or drill a few holes in the cover of the airbox to let some more air in to balance the larger jet out.

[kopis]

Thanks for the reply

I forgot to mention I replaced the jet back for the original 82 size and it didnt help.
I also replaced the spark plug as it was covered in black carbon, with no luck

[streido]

Did you reconnect everything properly?

Black plug would indicate its running too rich, prob from the 84 jet.

Check the air box intake hose isnt kinked and the intake hose clamp is tight on the carb.
Also check the manifold that comes out the other side of the carb and goes into the engine os on correctly and not burst or leaking.

Could be something as simple as dirt in the carb from when you were in there?

Does it idle ok? What year is it and what mileage?

[Kenho21]

Definitely check your connections as Streido said, even with and 85, what I had a one point with a stock setup, the scoot should sill run and drive. I think there's even some manuals online that can be found that show where all the hoses and stuff go.

[The Rookie]

Jet fallen out and running mega rich?

[kopis]

It is 2009 A50 , 8000 km on it, recently changed oil and spark plug and air filter.I am step by  tryin to derestrict the girl, changed the variator boss about 1000 km ago, the main jet was a step 2. I ordered a derestricted cdi and I want to replaced the old one as soon as it arrives.

I dont think it was running rich as everyone recommends this for basic derestriction without any changes of the air filter....anyways it is in Streidos  own Newbies basic guide to derestricting
Double checked all the connections and everything seems to be ok.

@The Rookie: Jet was properly in its place, I replaced it back for the original 82 but still the same issue...

My last shot is to remove the carb and clean it properly which involves a lot of stuff I never done before.I tried to avoid this but im running out of ideas...

[streido]

It def sounds like a fuel or air problem, like too much or too little of one of those.

It shouldnt run rich on the 82 but the 84 may have been a little on the rich side. Still it shoud still run ok on an84 as kenho said.

Without seeing it its difficult, if it was me i would check my fuel filter is clean and all fuel lines are not kinked or being squashed or pinched anywhere. Also just check the new plug and make sure its gapped correctly.

Does it rev up ok on the main stand and is it only when you try ride it it dies off? Or does it do it even on the stand?

[mono]

Both my Agility 50s have developed a condition recently where they would idle way too rich regardless of the main jet or idle mixture screw setting.

While they're running just fine at WOT as always, they both stall for a second when opening the throttle after decelleration (and this can only be cured partly by disabling the air cutoff valve and acceleration pump) and the plug is always black with dry soot after running idle for less than a minute or so. ( _if_ they idle for that long, that is)

Cleaning the carb only made this worse in both cases for some strange reason, and I've spent a month reading everything I could find about this type of carb and testing every single detail of them. I finally gave up and just bought a cheap chinese carb for one of the scoots, which is running fine since...

One point I want to make here is that the idle circuit can mess up an otherwise perfectly set up carb and foul your plug while there's nothing wrong with your main jet setup.

Another point is that you wouldn't be the first who never gets these carbs running again no matter what you try. I suspect that the OEM Kymco carb has a small design fault somewhere which is perhaps aggravated by a recent change in fuel additives by the oil companies. Fact is that a few Kymco dealers I've spoken to admit that they just replace the Kymco OEM carb for a cheap chinese imitation at the first sign of trouble, sometimes even when new...

[streido]

My 2008 agility still has the original carb, never had a problem with it even after 21,000km and mustve rejetted at least 10-20 times on various set-ups over the years.

If i did begin to have issues then i would just buy a complete new china carb, that would prob work out cheaper than buying parts for the Keihin carb.

[mono]

My 2008 agility still has the original carb, never had a problem with it even after 21,000km and mustve rejetted at least 10-20 times on various set-ups over the years.

That's the funny thing, one of my agilities is a 2006 which has also run about 20000 kms and has also seen many rejetting and cleaning sessions, and the other one is a 2010 with only 10000 kms which has probably never had its carb touched since leaving the factory - and both seem to have developed the exact same problem at almost the same time just recently...

[streido]

Weird   

Could be the additives then in your country or it may just be co-incidence. Guess if it is the fuel then it will end up doing the same to the new carb you got tho.

[whiteknight]

my old carb developed a problem where the  diaphram wouldnt control the amount of fuel properly so basicaly stopped giving fuel altogether. just swapped the old carb for a 19mm race carb runs quick but the spare 50cc cylinder i have fitted hates it.

[Kenho21]

Kopis- Could you post a picture of your carb setup so we could take a look? I see things better with pictures than with words, no pun intended...

[mono]

Could be the additives then in your country or it may just be co-incidence. Guess if it is the fuel then it will end up doing the same to the new carb you got tho.

The new one is from a different brand (no brand that is :-) and is constructed slightly different at most points, so I hope it doesn't have the same weak points as the OEM ones that I happened to get.

@ kopis : Grab a copy of the service manual for an in-depth explanation of carburettor disassembly and cleaning. Just do the whole exercise as described, take care to do the work with clean hands and tools in a dust-free environment and it should be fine - if it isn't, I would buy a brand new cheapo replacement carb...