GY6 Not running after sitting for 4-5 weeks

[subydrift]

Hey guys, I rebuilt the GY6 in my son's Crossfire and it was a great runner for probably 2 months. Started right up, idled strong, never any sputtering or dying issues. Well it's sat in the garage for probably 4-5 weeks and now it will not stay idling. It will turn over for a couple seconds but then die. When I first start it any blip of the gas will kill it. After I've tried to start it for a few minutes I can keep it running by hitting the gas pedal slightly but it still dies as soon as I let off. What can I check or adjust to get it running like it was again? I'm not super familiar with carbs but I know it has an idle speed screw adjustment and I think an idle air screw adjustment? It was a brand new carb from BDX Performance so I can't imagine its gummy inside alreaady? It's always had premium in it.

Appreciate any input or tips.

 

[subydrift]

I think I'm gonna pull the valve cover and check the valve lash. Sounds like that is a common symptom for if the valves come out of spec.

 

[Snaker]

Ah, yeah the carb is gummy inside already.
But don't go turning the adjusters all out of wack
If it was running good before where they are set, it will run good again at the same settings.
Be sure to carefully note where any adjusters are BEFORE you start dismantling.

 

[panchothedog]

Once you get it running again mix in some " stay bil " fuel stabilizer. The fact that you always ran premium fuel means nothing other than you spent more on gas then was necessary. Not high enough of a compression ratio to need premium.
If the carburetor has a fuel shutoff, always turn off the gas and let the engine run until it runs out of gas and dies if the kart is going to be sitting any more than a week. I have 4 karts and a mini bike. I ALWAYS mix fuel stabilizer in the can. During the summer months when its too hot to go to the desert, they sit for at least 5 months. Come November, when it cools down, they fire right up like it was yesterday. More than one brand of stabilizer, I'm sure they all work just fine.

 

[subydrift]

I took the carb apart last night and found out I need a better air filter. Lol. There was some small gunk in the main jet needle area so I cleaned it all out and swapped the main jet from the old carb into the new carb and she runs way better than before. I think I was running super rich before. I also readjusted the valves but they weren't too far off from spec so that's good. I have some fuel stabilizer I use for storing our boat so i'll be sure to use that going forward to prevent bad gas again. Thanks for the input everyone!

 

[Denny]

The blue Sta-BIL for boats is the best!

 

[BrownStainRacing]

I took the carb apart last night and found out I need a better air filter. Lol. There was some small gunk in the main jet needle area so I cleaned it all out and swapped the main jet from the old carb into the new carb and she runs way better than before. I think I was running super rich before. I also readjusted the valves but they weren't too far off from spec so that's good. I have some fuel stabilizer I use for storing our boat so i'll be sure to use that going forward to prevent bad gas again. Thanks for the input everyone!

If your main jet was clogged, check your fuel filter too. Sounds like something got passed it.

A good see thur filter with a paper element seems to work pretty good.