[img]i/expressions/face-icon-small-disgusted.gif[/img] Certainly, there's got to be a higher source of help when you are faced with a tough troubleshooting problem. I appreciated the help I got from you guys, (It's still more than welcome!) but I am stumped and running out of options on this damn problem I'm having! At full throttle, my Raptor acts like it's running out of fuel, as it will backfire a couple times and die. I coast to a stop and after a few seconds it will start back up. I'm not sure now that it is carburetor related, because I have checked and double checked everything, with no problems found. (all specs are normal) All this seemed to start when I installed a Sparks ignition advance key, but continues even after I took it back out. The engine also seems to be prone to backfire when stabbing the throttle open from idle. I even get a puff of fire out the exhaust. I feel like something is boogered up with regard to ignition, but WHERE do you start to isolate the cause? I don't feel like changing out everything, both from a hassel and a cost standpoint. I basically have a quad I can't enjoy until I find out what this glitch is! THEREFORE, who is the answer guy at Yamaha in instances like this? I need a phone number or a direction to who to consult with. I do not trust a dealer on this one, as I feel like most of the mechanics are not qualified, and I don't want my bike beat on in the hands of some yahoo. I have serviced every mechanical aspect of motorcycles and quads for many years, and trust my own workmanship, but I need some clues on this one first! Anybody with any info, please post asap!

 

Try this if you havent already.. Take the gas cap off, flip it over and take the screws out, take out all the crap inside and put the cover back on, and cut the vent tube to like 4-6 inches or enough so the end isnt touching and the tube isnt crimped. Sounds like it is starving for fuel, my blaster did the same thing, did the stuff above and hasnt done it since, it would only do it WOT 6th gear.

 

Yeah, I've covered that base too. This won't be an issue, because I've replaced the stock gas cap with a billet UMI cap that has a straight-through vent hole. It flows air great. See why I'm so frustrated? Keep the suggestions coming though! When I finally find this problem, it's probably gonna be something stupid.

 

Scott, what were your mods?

 

Dude, It sounds like it may be your parking brake. See if you have any play in your parking brake lever....The parking brakes acts like a REV limiter whenever it is engaged in the very least. Happened on my bike...I took the whole parking brake asembly and cable off.[img]i/expressions/face-icon-small-wink.gif[/img]

 

Mods as follows: Yoshimura Titanium full exhaust with spark arrestor core, jetting: 170/175 w/ 27.5 pilots and needle raised one notch from stock (richer), Pro-flow filter setup with drilled air box lid, had a Sparks advance key in, but took it back out after I suspected it initiating the problem. (Not so sure now) Lots of other mods, but that's about it to the engine. I am very convinced that my problem is IGNITION related, as it wants to backfire and will not accept full throttle more than about 3-4 seconds before the fits start. Only under hi load, but I can feel what I believe to be slight missing under light cruise. Thanks for the tip with the parking brake switch thing...I didn't feel like that would be a possibility, but I will try anything at this point! It's gotta be something stupid! Keep the suggestions coming!

 

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From What I can gather from what you have said I would say it is definatly an electrical problem more than likely the timing I would say!
It is adjustable behind the flywheel cover. Keep us informed and let us know what it is.
I know how annoying it can be I had major problems with my old Big bear and it turned to be the a little thing called the Exciter coil oh well Good Luck From Dave