I have a 2005 yamaha yfz 450. Iam having a little problem with it. The quad cuts out on me in all the gears except first gear.I thought it was a bad spark plug and i changed it and it did nothing. But spark plug was really dirty and a little rusted. So my next guess was it was not getting a enough fuel and i fixed that and it is no better. I was just wondering if anyone had any other ideas thank u.

 

Without any details, like what your jetting is, what mods you have, does it cut out on acceleration or deceleration, it's a little difficult to say why it might be cutting out.

It could be a lack of airflow instead of a lack of fuel as well. If your spark plug was rusty and dirty, your air filter probably needs to be cleaned.

And please don't take this the wrong way, I'm not trying to be an ***...did you make sure you put the choke back in after you warmed it up? A buddy of mine was having problems with his yfz and couldn't figure out what the problem was...a month later, after practicaly tearing his quad apart, he realized that he left the choke on. lol

 

the only mods I have are a yamaha pipe gytr, After market air filter, uni, aluminum air box no lid, cdi box. It only cuts out when I accelerate. I put a moose jet kit init and the main jet is a 145. thank u if that helps at all i would appreciate it thanks again and the choke is in right position .

 

Moose jet kits are the same as dyno jet kits which alot of people have had trouble with in YFZs but i think Your jetting is way to lean, I would try a 170 main and then go up from there and see. And did you change the pilot and clip settings at all????????

 

yes i changed all of that i will try to go up acouple more if that does not work could it be electrical problem

 

Not real sure but do the YFZs have the parking break sensor?? If so if that is just ever so slightly enganging then it wil cause the motor to cut out at higher rpms badly. Been LOTS of people with this problem on raptors and other bikes. So may want to check that out before you start doing alot fo checking on it. Especially if it just all of the sudden started happening.. Like parked it one day fine.. next weekend went to start it up and ride off and it started doing this.

Hope it helps!


Kevin

 

I'm running a 172 or 182. I forgot already, but, it is one of those two. I have full exhaust and twin filter.

 

Sounds like it's probably your jetting. My mods are similar to yours and I'm jetted at 170 main, 45 pilot and 3rd clip on the needle at sea level.

 

i try to change all the jets and stuff today and it did not work u have any other ideas thank u

 

did u find a solution beacuse im havng the exact same problem