Grandvista 250 stalling on idle

[Ranj]

I have a 2009 Grandvista 250.  After not using my scooter throughout the winter (and failing good winter storage practices!), my scooter now dies when idling.  It doesn't matter if the scooter is warmed up... same problem.  I tried adjusting the idle screw, and no response whatsoever to adjustments.  Hoping someone could help me before I take it to the shop.

[ScooterLar]

You're gonna need to pull that carb off and inspect/clean the idle jet. It has tiny orifices in it that easily clog up with the smallest bit of debris. I had the identical problem with my GV when I bought it. It too had sat for some time and sure enough, the jet was clogged. Ethanol in the gas will gel when gas goes stale and clog your jets.

[Ranj]

Thanks.  I've learned my lesson on winter maintenance.  I'm also going to start using alcohol-free gas from here on out.

[pipster326]

Yep, gas sitting in the tank all winter, is a no-no. I put Star-Tron gas enzyme treatment in my DT300. I also start and let it run for several minutes, if it's gonna sit and not be driven.Actually, I use the Star-Tron all year round. An ounce or 2 will treat like 5 or 6 gallons.


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[doublej]

Use Seafoam in the gas for a few tankfuls then once a month thereafter. Also tape 2 aspirins to your forhead for future problems....

[mrbios]

I have a 2009 Grandvista 250.  After not using my scooter throughout the winter (and failing good winter storage practices!), my scooter now dies when idling.  It doesn't matter if the scooter is warmed up... same problem.  I tried adjusting the idle screw, and no response whatsoever to adjustments.  Hoping someone could help me before I take it to the shop.

Everyone is right about the pilot jet but... the real problem is the passage that gas must travel through after it leaves the pilot jet it is extremely and needlessly tiny.  A 25 gauge wire can barely fit through it.  Once this passage is clogged or restricted the idle mixture screw will have no effect because little or no gas will reach it so turning the screw counter clockwise will not add any additional fuel.  If you want the scoot to run perfect spend ~ $250 for a new oem carb + labor and the problem will be solved (unless it sits with old gas). 

These videos show the problem:


Carburetor Cleaning Part I   
Carburetor Cleaning Part II   
Carburetor Cleaning Part III   

[Dawsman]

I agree. A new, sealed in a plastic bag, KYMCO carb is the quickest and cheapest fix. Comes preset from factory (air/fuel etc). Its like giving your GV a heart transplant. I had to do it on my 06 GV 250. I bought it used with 3100 miles. Ran ok then as soon as I got it home, the Fuel pump died on me, then after new fuel pump install the carb would dump fuel. New carb with auto by-starter is $299 from kymco parts monster. Easy install. Now purrs like a kitten.

[mrbios]

I agree. A new, sealed in a plastic bag, KYMCO carb is the quickest and cheapest fix. Comes preset from factory (air/fuel etc). Its like giving your GV a heart transplant. I had to do it on my 06 GV 250. I bought it used with 3100 miles. Ran ok then as soon as I got it home, the Fuel pump died on me, then after new fuel pump install the carb would dump fuel. New carb with auto by-starter is $299 from kymco parts monster. Easy install. Now purrs like a kitten.

When the carb dumps fuel the float needle is stuck in the open position (glued with old gas that has turned to jel).  Another user on this forum Jaybird replaced the carb on his 2009? GV250 and it runs perfect.  Since your pump had to be replaced at such low miles you know the gas was super old in the tank.  My 2005 GV250 has 20,500 miles on it but recently the off idle hesitation returned and I increased the pilot jet from #45 to #48 (remember #38 is what it comes with) and the hesitation is almost gone - the moral of the story - after many many cleanings the pilot passage that the pilot jet delivers gas to is tiny on these carbs which is extremely difficult to clean and I'm close to being an expert cleaner but problems still persist. 

Other carbs - different story.  I cleand virago 1100 carbs - no problmes, recently I did a 185cc 1980 4 stroke dirt bike, and a 2004 Yamaha Raptor 660 ATV - dual carbs feed ONE cylinder - runs perfect.  But Kymco doomed the GV with an excessively small pilot jet passage which is almost impossible to clean even with my special cleaning method.  Finally, I had a cleaning fail - cleaned an old 2007 chinese atv 110cc engine and got it to run but it would not idle right.  Replaced the carb (Jbird sent me a new one and also they are only $20 new) and it runs perfect like a the motor was swapped out.  The carb is truly like a heart transplant.