2010 yz450f fouling plugs?

Up until 2 week's ago I have run the spark plug that came in my bike from the factory, in the past hour and a half or so of run time I have fouled it and 2 others, my bike blow's some black smoke when free revving it. Once the plug is gone and the bike wont start anymore I can smell fuel pretty strong, instantly I can put in a new plug and it fires right up and runs fine, and it alway's run's what seem's to be fine right up until I shut it off and then it won't start the next time. I've checked my valves and they are in spec as well.... The only thing I can think is could it be a stuck injector that is fuel fouling my plugs? the smoking a bit started sometime a few month's ago around the same time I had no choice but to run cheap ampm gas for a ride day. Has anybody had this problem before?

I had some issues today at the hangtown track. I have the 2010 yz450 also. I pulled the cold start lever and the bike started fine. Then, Iit seemed to start loading up even after I pushed in the lever. The bike died and would only run for a couple seconds each time it resarted. It was blowing black smoke and sputtering. I haven't investigated the issue yet but it sounds similar to yours. Please let me know what you find out and I will do the same.

A buddy of mine has the same bike torn down for rebuild, I may borrow his injector and see what happens. It's just a hard time of the year to put hours on my bike as the only real ride time I get is racing arenacross

Have you tried running some injector cleaner, BG44K or chevron techron, through the fuel system? Seems that recently someone used stabil fuel stabilizer and it had gummed up the injector to the point of it not closing and once he ran some injector cleaner through it ran fine. I'd give it a try.

Have you tried running some injector cleaner, BG44K or chevron techron, through the fuel system? Seems that recently someone used stabil fuel stabilizer and it had gummed up the injector to the point of it not closing and once he ran some injector cleaner through it ran fine. I'd give it a try.

I considered this but not sure if it was a good or bad idea. Now hearing someone else has done it with positive results that is my next step, thanks.

I have done "repairs" on two of my own cars with injection cleaner that were estimated to cost a total of $1500.

All reputable brands of injector cleaner are the same basic chemistry as the stuff that's already in pump gas ("Techroline", etc., mostly all the same stuff), just in a concentrated form so that by adding it to the fuel, you simply boost the content of something already there. Read the label to get a rough idea as to how much to put in your gas and don't worry too much about getting the ratio exactly right.

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