Help...my bike keeps stalling...WTF???

Hey all, I just bought a new 2002 in April of this year (15th). I now have 8,360 miles on the bike. Only thing I have changed was I put a K&N Air filter in it and a Jardine slip-on exhaust. That's it. No other engine mods. However, lately it's been stalling on me. Let's say I start it up and warm it up till it hits 104*F Then I'll start to ride it for a min...if I rev the bike up (3-4K) and then let it drop to idle it stalls out. I thought it only did it when it's cold..but nope. Does it when it's at like 200 something degrees too. I came up to a light and pulled in the clutch, reved it up (not insanely, but just to like 3-4K) and she died when it came down to idle. Plus, it does seem like my bike is idling around 750 rpm now too. Seems lower than when I first bought it. This only started doing this around the last 3 weeks or so...actually I think it started either just before or just after I went down the other week. I don't know if it's a coincidence or not. But I think it does seem to be getting worse (more often) as I get more miles on it. So, it didn't start doing this when I put in the K&N & Jardine...so I don't think that is it. Any suggestions? Only other thing I've done to it is normal oil changes around 2,500 miles each time or so. What gives? Please help cuz this is driving me nuts! I wouldn't think fuel injection would act this way. I thought maybe the plugs???? I haven't changed them yet...they are still the orignials. Please help with any suggestions or if someone had this problem, how did they fix it. Thanks tons in advance! Mat

I would not guess plugs, if it is already running and it starts back up they are not fouled. bad plugs would make a rough idle and hesitation power loss, or no start if they are fouled. fuel injection can run just as shitty as carbs, trust me or at least it does on cars. you may have an air leak in your intake system. take your tank off and see if anything got jarred from when you went down. this should also cuase rough idle and I think you mentioned something about the idle. you could also have a leaky injector, pull your injector rail turn on you key to build pressure, don't crank, and see if they leak. you could also crank it to check your injector spray pattern, should be a fine mist with no drips. if its not an air leak or fuel prob. then it could be a ignition box fault. it also could be your injection computer, or false intake readings to it. not sure if ignition and fuel are the same computer, they are on cars. you may need to go to the shop. but start with the basics see if anything is leaking or displaced from going down. and yes an engine can run next to fine with a leaky injector its when they stick open that they almost don't run. hope this helps Mat good luck man, I am a mechanic for benz so feel free to aks any questions if you get stuck

Hey man... Thanks for the info. It idles around like 500 and the power is a bit sluggish down low from what it was before. Plus, I know Yamaha recommends changing the plugs at 8K, so that's why I was wondering. Damn I hope I don't have any engine damage from going down..that will suck. I hate it when I don't know what i'm looking for exactly. :( However, thanks for the info. I'll print it out and maybe check for those things and since I'm already in there, I'll just put plugs in it. I have to change the oil this weekend anyway...so might as well do the plugs I guess and make sure everything is tight. It's just a pain in the arse at lights or what not. :( Plus, I'll be pissed if I have to replace an injector or somethign when the damn thing is 3 months old!!!! Shouldn't that be covered under warranty? I know if I take it in, they will just say some crap about it having to be cleaned or something and then charge my arse instead of warranty covering it. Man this sucks. Thanks for the info.

well if you do take it in the estimate should not be much at all. it could be plugs if you are having power problems when running. that does happen, espeicially under load, but runs fine on light throttle. does it chug at idle. the only thing that really should of happened from dropping it is flooded plugs ( fouled ) or some boot on your intake system got dislogged. if it is an injector problem or computer fault than it should be warranty no matter what. unless your engine fell out and it hit the ground. most shops are cool about warranty unless there is phisical damage or alteration that yamaha would see when the parts are returned, bouncing the claim. wich you have done none of. it should be full warranty. just put in new plugs and make sure all rubber boots are clamps are secured. if needed to tell you can loosen clamps and wiggle the boot to make sure it is seated. also start it up and lightly spray brake clean around the intake track, making sure not to spray directly into the air filter intake. check your filter for excessive dust build up while you are there. if you have an air leak you will see a noticable increase/decrease or combo of engine rpm, it may die if the leak is big. usaually it will drop when you spary and rev up when you stop. any flamable solvent will work. I use this method daily just to make sure engine do not leak, it also covers your arse after a major disassembly. I will email you with spray can trick so you see it soon. if none of this fixes it you should have an estimate done and most likely it will be warranty.

Thanks man.. I appreciate your help. Going to install new plugs tonight and see what goes. I'll also double check everything since I'll have the bike apart. I just wish I had something to hold that damn tank up...farkin' thing gets heavy. I remember it last time when I changed my air filter to the K&N. :eek: However, this time I only have reserve fuel in it. :D