07 EX250- idle issues

[GirlScout500]

Hi All:

My recently acquired 2007 EX250 came with idle issues. It has been down (in dirt) twice and was filthy when I bought it. At purchase it would run with the choke on but die as soon as the choke was weaned off or if you tried to rev it.

Carbs were removed last weekend. They obviously had water in them at one point: rust, dirt, oxidation. They were completely disassembled, flushed, and cleaned well. The tank had what sounded like a handful of shale in it. It, too was flushed numerous times and cleaned well. All lines were cleaned and flushed. Petcock was disassembled and cleaned. The bike was power washed and dried with an air hose to remove all the dirt.

We removed the emission plugs to get at the soft idle adjuster screws and adjusted them according to the manual. Idle was set at 1400RPM.

The bike is running great until I ride it around long enough to warm it up- then it doesn't want to idle anymore. The idle speed slowly decreases below 800 revs, then stals.

Question: Once the carbs are warmed up, does the mixture tend to go lean or rich?

:madHELP!

 

[altomista]

When was the last time it had the valves adjusted?

 

[GirlScout500]

My guess is never- it has 1016 miles on it.

 

[RLFore]

How did you set the idle if the bike can't warm up properly?
You should set the idle speed after the bike has warmed up.

When the carbs were cleaned, were the o-rings and jets replaced? Was the float height adjusted? Was the mixture screw checked to make sure its at the stock setting? Sometimes, there is a plug covering up the mixture screw that has to be drilled out so you can remove the mixture screw and clean it. You can get a K&L kit for the o-rings and float gaskets. But you have to order the jets from bikebandit.com or a dealer.

When you have the choke on, the carbs feed it a richer mixture to raise the rpms and when you turn it off to ride it, the mixture goes back to the normal setting so I assume your mixture is running too lean.

Were the carbs sync'd?

Did you give everything a once over like air filter, spark plugs (you can tell alot of problems by how the plugs look) ...

 

[GirlScout500]

The bike can idle all day long in the driveway, until you start riding it around. We had it idling for 10-15 minutes in the driveway before dialing in the idle (last weekend and this weekend both). Then I'll ride it around (~two miles) and go to pull the clutch in at a stop and the thing will slowly drop idle until it stalls.

Nothing was replaced when the carbs were cleaned, they were just thoroughly cleaned. The carbs were synched though. When I wrote the "soft idle adjuster screws" in my first post, I meant the mixture screws. We removed the plugs covering those screws and adjusted them 2.5 turns (if I remember correctly)

All the idle issues are happening without any choke. We have played with the idle, setting it to 2k RPM, but it'll still stall oout after a couple miles of riding once the clutch is pulled in.

It's otherwise running like a champ.

Air filter was cleaned...didn't check the plugs now that you mention it.

Any suggestions for tomorrow's work?

 

[altomista]

Check the plugs. You might as well replace them since you have them off. Gap is at 0.6 mm - 0.7 mm. It's only $4 for a pair.

If they're fine, it's your valves like I suspected before. PO probably didn't have them checked at 600 miles.

 

[209manny]

does the ninja 250 have a fuel mixture screw on the carb? My bike was running rich and I had to lean the mixture up a bit by turning the screw about 3/4 in. It would idle fine then slowly want to die when coming to a stop. Needle height was set too rich and pilot jet was rich as well. I leaned out the needle and adjusted the screw accordingly and it runs fine now

 

[altomista]

does the ninja 250 have a fuel mixture screw on the carb? My bike was running rich and I had to lean the mixture up a bit by turning the screw about 3/4 in. It would idle fine then slowly want to die when coming to a stop. Needle height was set too rich and pilot jet was rich as well. I leaned out the needle and adjusted the screw accordingly and it runs fine now

3/4 turn back in on an EX250 would put it back at the OEM setting, really lean to pass EPA regulations. 2.5 turns is around where it should be. Mine's at ~2.75 turns.

 

[RLFore]

If it were valve clearance problems, she probably would hear tick tick tick tick
I say check the plugs and perhaps take a pic of them and post them.
Other quick option to try besides plugs is to set mix screw at 2 turns

A pic of the plugs would help out