yz450f sputter at low throttle

My 2009 has the same stutter at 1/4 steady throttle. Gray was right about the tps unplugging. I found it interesting that on JD jetting web site that Yamaha 450's are designed to do this and it can't be fixed... something about the ignition. When racing you don't notice this, which is what these bikes are designed for.

Since neither of my '06's do it, I doubt they're designed to. I know several people who have made this problem go away.

I discovered the sputter at low throttle was due to the air filter being completely nasty. Didnt occur to me to check it at first. The guy i got it from put wayyyy to much oil on this thing. different beast with a clean filter. lol

Be advised that the only thing that makes a foam filter filter is oil. Also you should know that the air box of the '06-'09 models is an extraordinarily dirty place. Plan to clean and oil your filter after every day's ride.

Be advised that the only thing that makes a foam filter filter is oil. Also you should know that the air box of the '06-'09 models is an extraordinarily dirty place. Plan to clean and oil your filter after every day's ride.

I will second that, I can ride a short practice round (indoors even) and think ahh my filter can't be that dirty from that little nondusty ride. I will check it and the entire airbox will be coated in a film of dust.

ill keep that in mind guys thanks. My other bike i had a k and n filter on and i cleaned it religiously. But since he said they didnt ride it much i didnt think to check the air filter at first. I was completely amazed at the filth.

i bought a new air filter.. Put a uni on there. Still have sputter and popping so i am thinking i may need to rejet. I am in kentucky around 700 to 800 feet above sea level. any suggestions as to a jet kit. i am thinking maybe a jd kit or a dynojet kit.

Have you disconnected the TPS yet? That will take the low throttle sputter away immediately. To get rid of the back fire you will need to richen the jetting and adjust the fuel screw to the sweet spot between bogging and backfiring on decel.

no i havent messed with the tps yet. hmm next warm day i will try adjust few screw and disconnect the tps. thanks.

Instead of starting a new pointless thread I shall resurrect this one. I got my bike back today from my mechanic and I must say WOW!!! GOT it properly jetted, sag adjusted to my height weight, new chain and sprockets, and the seat shaved down. I officially can wheelie in fourth gear, no low end sputter and can flat foot one side. Im stoked !!! just wanted to share.

How tall r u? My girlfriend was 5'3" and couldnt hold up anything bigger than her TTR125L haha

i am also 5'3. But i have been riding since i was 7. That def helps.

Gotchya. My ex wasn't an avid rider and had only been riding for like 5 years. Ashley Fiolek is also 5'3".

yes she is my hero. literally. i wrote her on her page and she actually responded to my email. I was completely stoked.

Yeah she's pretty awesome. She gave me her email address and I sent her a copy of her book and she actually signed it and sent it back!! I emailed her a few times about riding tips and what not and she responded every time!! Pretty badass eh? Definitely my hero.

Here's a pic of my daughter with Ashley Fiolek from Southwick.

AshleyFioleck2.jpg

that is completely awesome. I think she is great. I would love to someday meet her myself.

Instead of starting a new pointless thread I shall resurrect this one. I got my bike back today from my mechanic and I must say WOW!!! GOT it properly jetted, sag adjusted to my height weight, new chain and sprockets, and the seat shaved down. I officially can wheelie in fourth gear, no low end sputter and can flat foot one side. Im stoked !!! just wanted to share.

So the sputtering was due to jetting? B)

Cool that you got that, and a couple of other things, fixed! :smirk:

Jimmie

So the sputtering was due to jetting? :smirk:
I've said that right along, but who listens to me?
So the sputtering was due to jetting? B)

Cool that you got that, and a couple of other things, fixed! :smirk:

Jimmie

yeah oddly enough it was. The slip on from white brothers suggested stock jetting. so he just moved my clip up one and wahhhlahhha.

well that and a lil turn of the fuel screw.

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