Hey, i'd like to find out if someone could give me some info.  My bike, when i'm traveling at highways speeds(60 mph+) and then come to a stop at a light or whatever, the bike will just shut of when i pull the clutch in.  It does this also a city speeds too(30 mph+) but not as often.  If anyone could shed some light on this situation i'd really appreciate it!!! Thanks!

need some more info.  whats your idle set at?  gas level in the tank?  how do vac lines look that goto the petcock?  anything else that you may think isnt that important might be we need more info

I'm going to go with petcock problems here, which is a mostly random guess based off of sheer probability... Try running in prime and see if it gets any better... Also, are you sure it is when you pull the clutch in exactly or just that the bike won't idle after riding at highway speed? I'm guessing you're having fuel starvation problems that are not allowing you to idle which could be a number of things. In order of probability they are: faulty petcock, clogged tank vent and dirty carb.

You should experiment more with the problem and be more detailed in your description. I'll still be guessing, but the more you tell me, the less random my guesses are... Try running on prime and see if anything gets better. Also describe a little more what happens exactly when it stalls on you. Does it start right back up or does it leave you unable to start the bike for a few minutes? If you rev the bike up as it looks like it is starting to die, does that help? Is there any way you can keep it running? How exactly does it die? Does the idle just keep getting lower until it stalls or does it cut out on you very fast. Also, do you notice anything unusual when you're riding but before it stalls? Does it act like it is running out of gas on you when you know the tank is full (double check by actually adding gas, looking in the cap is really deceiving)?

I know this thread is old, but it seems pertinent to how my bike is behaving now that I have it back together and would like to take off on where this dialog left off to diagnose the issue with the bike.

Originally, the bike would stall immediately every time the clutch was pulled in coming to a stop. Idling and starting seemed difficult; in general it was difficult to keep the bike running without revving the engine. After checking the valves, found both the exhaust valves were too tight. Went down 3 shims on LHS exhaust valve and 2 shim sizes on RHS exhaust valve. Helped immensely.

Bike seems to idle very well at 1200-1300 now. Starts easy. Runs nice, and does not stall immediately anymore with the clutch pulled in. However, it will still occasionally come to a gradual stall--not immediate like before. It's almost like the bike wants to keep running, and it slowly cuts out. When I turn the petcock to prime, it does not seem to have this issue. Nothing unusual when accelerating and shifting. I checked beforehand when doing the valves to make sure that all the jets were clean.

Questions:

Is this a bad/clogged petcock? Do I need to buy a new petcock, or can I just blow it out with compressed air? Is the tank vent tube the one in the middle on the underside?

i actually had this problem too today.

it was riding fine then after 20 miles or so i pulled the clutch in and released the throttle as i came to a stop light. then it just died. i was able to start it up again, while giving it gas. i just kept revving it until the light turned green.

then at the next stop light the same thing happened but it wouldn't start up again. i waited a couple secs and tried again with no luck.  so then just for the hell of it i put the choke on and it fired up no problem. wtf? i let it idle for a little bit, turned the choke off, then i was able to get home without another incident.

really strange

About the pet chicken problem get rid of that stupid vacuum petcock if you haven't already and just run a normal petcock i have had those things cause more head aches than I car e to remember. Just get a normal petcock and plug the secondary out from the tank. Problem solved or at least problems get simpler to solve plus you loose a couple lines while your at it. Now if only I could fine a cheap flat slide carb set up for the darn thing.

Quote from: Poorboy on September 09, 2010, 08:48:48 PM
About the pet chicken problem get rid of that stupid vacuum petcock if you haven't already and just run a normal petcock i have had those things cause more head aches than I car e to remember. Just get a normal petcock and plug the secondary out from the tank. Problem solved or at least problems get simpler to solve plus you loose a couple lines while your at it. Now if only I could fine a cheap flat slide carb set up for the darn thing.

Is there a particular petcock that you would recommend to replace the stock one which is pretty much direct bolt on?

There is an eBay store (i lost the link) that had a HUGE selection of petcocks. The owner actually measures each model of petcock - width between mounting bolts, height with and without brass tube, etc.

Alright, so does this sound correct: I get one of these simple single input petcocks, run the reserve output from the tank to it, put a cap over the other fuel outlet adjacent to it, then run a tube from the output of the petcock to the brown T on the carb. Do I also just cap off the opening that the vacuum hose runs to on the left carb? That's it? This means that I won't have a reserve and will just have to keep an eye on the number of miles ridden or eyeball how much gas is in the cap at a given time?

Nevermind, I found the CRF250X petcock mod thread. I'll give it a go. Thanks for the replies.