Carburetor help - new YZ450f

I tried to search, but the words stall or stalling bring up every post from install to stalling and most of the posts about stalling have to do with flywheels... :thumbsup:

Anyhow. I got my new YZ450 today and it's got some jetting issues. I've read mention of these problems before, but I couldn't find any of those posts.

The bike is difficult to start and stalls on idle. I was able to get it started, and keep it running with the throttle, and when I decelerate it gives the popping that I've read is from being too lean. The only way I have been able to get it started is to hold the hot start in, which I only knew to try because I'd read it here.

I tried to start adjusting the screws on the carb, but it started getting dark on me so I'll have to tinker more tomorrow.

The bike is brand new and should have stock jetting. I have to talk to the dealer tomorrow anyway and I'll ask him if they changed the stock settings.

Also, does anyone have any tricks to get to the pilot adjustment screw?

The only thing I can figure is that you have to take the carb off to adjust it. I think that may be part of the problem I'm having as the TTR125L I also got for my wife needed the pilot screw adjusted to keep it idling too. I was hoping it would be that simple but I know the YZ450 is a much more complicated machine than the TTR is.

Anyone have any ideas for me to start with?

BTW, that thing kicks some serious butt doesn't it? :devil:

You should get an aftermarket "fuel Screw" . It will let you adjust it on the fly. That along with your idle adjustment will get you started in the right direction.

You can order one from the TT Store:

ZipTy Fuel Screw

So you think the best place to start is by adjusting the fuel screw?

just from what you have described this is where I would start. Then you can tweak the jetting if needed.

This is going to sound really stupid...

Is the fuel screw the same as the pilot screw?

The one in the bottom of the carb?

This is the first dirtbike I've had in almost 20 years. Be patient with me.

Btw, I ordered the Zip ty fuel screw. I wanted one of those anyhow.


yeah its the one on the bottom of the carb, its recessed into the float bowl. u can get it it with a tiny screw driver. if its lean turn it out (counterclockwise) to make it a little richer, and twist ur idle knob clockwise so it doesnt stall on you

correct me if im wrong anyone, its been a little while since i messed with mine.

I think the best thing you can do is get the james dean jet kit. its perfect

This is going to sound really stupid...

Is the fuel screw the same as the pilot screw?

The one in the bottom of the carb?



also see this thread:

jim aka the wrooster

'01 wr250f

Thanks for the responses guys. I think I know what direction to go in now.

wrooster, I sure hope you never get tired of doing that. Thanks.

Believe it or not, I actually tracked you down to click the link in your sig to the faq hoping to find the info you posted. I guess next time I'll just go to the sitemap. :thumbsup:

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