2012 YZ450 Running Rough

Hi guys. My 12 has 40 hrs on it, its been parked for a month now. I run 94 Chevron non ethanol and put a bit of Stabil in it after the last ride. I fired it up twice in between. Got a Pro Circuit pipe for Christmas and put it on last week. It seemed to run a little rough on the stand then but I just figured it needed to have some fuel run through it. Topped off with fresh fuel this morning and took it for a ride, it started up fine but at part throttle it ran like crap, wouldnt clean up until high rpm WOT. Had only a little luck with the tuner and only when I LEANED out the bottom end but it was still pretty crappy. There is no leaks at the pipe and the airfilters spotless. Seems to be brutally rich. Get the bike hot, no difference. Seems like theres a few things to make this bike quit or run lean but not too many that cause it to run so rich? The tuner shows no codes or problems, airfilters spotless, new plug makes no difference. Im wondering if the injectors somehow fouled? Maybe by the Stabil? Any of you have some thoughts on this one? Thanks. Dave

I am guessing that your bike is not properly mapped to the pro circuit pipe unless you claim it ran great when you first put it on. The gas cannot be the problem, however check your air filter, those filters in the front of the bike clog up pretty quick and can rob performance from your engine. Thats all I would know about the new bikes, problems like fouled injectors just dont happen on bike with 40 hours on them, (extenuating circumstances exist of course)

Check the operation of the temperature sensors, both the coolant and intake air.

Check the operation of the temperature sensors, both the coolant and intake air.

Thanks for the reply Gray.

The coolant, intake air temp, water temp and intake air pressure sensors all seemed to be reading normally as well as the Tps. At least according to the tuner, so I never pursued them. Hold the throttle steady at say 5-6 grand or lower and it misses steady. Snap the throttle and it revs up ok from there. I ended up taking it to the dealer (god help me) so we'll see if they can find it. I want the bike for the weekend and my evenings are full the rest of this week. Little bit annoying, one of my buddys has an 09 Kawi (first year FI) with over 200 hrs and his bike has always run flawlessly with no problems. He's loving this.

If it is in fact running excessively rich, and the sensor data and injector outputs are normal, you might have an injector that is failing to close completely.

That was my feeling too but if it was a piece of garbage in the fuel would the filter not have picked it up? Im careful with my fuel, the only other new factor was the Stabil, I wasnt sure if it could actually foul the injector. First time I used it in one of my bikes, maybe just coincidence.


So I ran some injector cleaner through the bike and now its running fine. Talking to a couple of snowmobile guys too that had to replace all of the injectors on one machine after it sat with Stabil in it. Once again, could be just coincidence but Im not bothering with that stuff again. At least not in that bike.

Naw it just took a Honda rider to take it for a rip and scare the crap out of it! LMAO! Glad its good again.. Spring is coming BRRAAAAP :ride:

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