Bike stalling in the cold

[Zxtritan]

Hey everyone,
I just got back from riding down to the store which is abour 3-4 miles away. I live in south florida, so the weather is usually not an issue, but today it was in the low 50's when i went out.  While riding, my bike kept stalling and bogging down.  I have no doubt that the weather was causing these issues, but I figured temps in the 50's was not low enough to lean out the carbs.  I just bought the bike about a month ago, and i saw that a K&N air filter is installed and i don't think the carbs were rejetted. you think this is contributing to the stalling??
Also, is there anything I can or should do to help fix this problem (spark plugs, rejet, etc??)?  O yea, and one more thing, after it stalled when attempting to restart the bike, if the fuel valve was in the "ON" position it had trouble starting, but when i turned it to the "PRI" position it started and ran fine.....why  
Thanx,
-Anthony

[juggernaught]

Might be running a bit lean.  Rejet may be necessary.  Low 50's wasn't an issue when i had my GS.  Generally when the temp was below 30 in NYC the bike might give me a bit of trouble but i often rode her on 20 degree weather and that's after being parked outdoors all night.

I'm sure one of the masters here can give a more definitive answer.  Good luck..!!

[hhgsm31]

how long did you let it run before starting out on the trip? If you fired and went like it was 80 outside, then she never had time to warm up in the 8 miles total. When it is cooler or cold, gotta start em in choke and let it warm up for a bit. I have always waited until revs went up and were steady before weaning off the choke, and made sure that I could rev up high with no choke before taking off, and then still be extra cautious at first (crossing traffic and pulling out)

[Zxtritan]

i let it choke for about 2 minutes. It would run ok with the fuel valve on the "ON" position until i got up to about 50mph, then when i pressed the clutch and cruised, i could feel the engine bogging and dying off. Then i would switch the valve to the "PRI", start it and wun with it on this position and it would run fine without stalling. why would it act differently with the valve in the "PRI" position?

[perfdrug]

put more fuel in it?
tons of us have stalled it thinking there was more fuel in it than there really was. even when i ran out of gas there was still some splashing in the tank. IIRC you should get about 130 miles on "ON" and then another 30 on RES

[scratch]

Check to the weather to see if there is a low pressure system moving in, that will lean out a bike enough to have a little problem, or exaggerate an existing one.  My bike has been suseptable to the weather on a consistant basis.  If your bike does this again tomorrow (provided the L-pressure system has moved on) then I would suspect some other problem.

The PRI postition probably provided enough fuel to counter-act the lean atmospheric condition.

[rangerbrown]

put more fuel in it?
tons of us have stalled it thinking there was more fuel in it than there really was. even when i ran out of gas there was still some splashing in the tank. IIRC you should get about 130 miles on "ON" and then another 30 on RES

well then you have a problem i get 210 per tank and thats before i switch to reserve, then there another what ever miles to that i have never found out.

[hayabusafiend]

50degF air won't suddenly make your bike your bike run like crap.  Don't focus on carb jetting or air temp until you've eliminated more likely suspects for poor running.

Let's start simple:  When is the last time the bike had a fresh tank of gas?  A partially empty tank condensates water and water goes to the bottom of the tank.  Moreover, old gas doesn't burn as well as fresh gas.

Gas age has no bearing on the petcock fuel position, so I think you have a fuel delivery problem.  The ON position on modern petcocks only flow fuel when there is engine intake vacuum (i.e. when the engine is turning over).  If the intake vacuum line is leaking air or the petcock ON position isn't flowing enough fuel, your carbs float bowls will be empty.  The next time the bike stalls on you turn it off and set the petcock to OFF.  Grab a shotglas and put it under the carb float bowl nipple (absolute bottom of the carb) and loosen the VERY SOFT phillips screw about 3 turns.  You should get about 1.5oz of fuel from each carb float bowl.
Remember to tighten the screw.

If the ON/PRI petcock position is actually irrelevent, then your carbs (namely pilot jet) are likely fouled with gas varnish due to extended sitting.  Refer to carb cleaning threads.

[Zxtritan]

welll, having just acquired the bike about a 3-4 weeks ago, i have yet to fill the tank with fresh gas and am still running on what the guy had in (don't know how old the gas is). I'll fill up tomorrow and see how she acts.

[hayabusafiend]

Assuming there's no rust in the bike tank, you can siphon the gas out and burn it in your car.

p.s. If you're not mechanically inclined or lack the proper tools, take the bike to a professional.