i bought an 04 yfz450 a couple of weeks ago. i bought it used from an auction. and i havent ridden it yet. it has been converted to kickstart. it usually doesnt start when i attempt to kickstart it. yesterday i kickstart it and it did start up. The carb is leaking gas from the bottom. and when i did start it up when i tried to put it in first gear. it shut off. twice i tried it. it also had flames out the aftermarket fmf pipe. which i guess is from carb acting up..do all this sound like carb probs. or what should i be looking at doing first to get it running the right way. and how can i convert it back to electric start. thanks and i am new to the forum great to be here.

There wasn't a YFZ450R in 2004.

FYI, IT WAS THE FIRST YEAR OF THE YFZ450.
By the end of the 2004 ATV racing season, three of the four National Championships were claimed by riders riding the Yamaha YFZ450: Keith Little, Brandon and Bill Ballance and Brett Oakley

oops i see what your saying wrong section.. sorry about that..

No problem, just keeo an eye out where you want to start topics. We generally like to keep things organized so anybody can refer to the topic in the future or through the search engine.


To begin with, I'd leave it as a kicker because you will probably have bigger headaches once you convert back over to electric in the future, plus you'll add about 12lbs. to the quad depending on what was removed from the motor.

Sounds like you may have a few simple kinks to work out of the bike to be able to ride it. The good thing is that it starts and idles. I'd would look to see where the fuel leak is coming from on the carb first.

Did the quad sit for a while without running?

sounds like it could use a rejet and more, make sure that all 4 screws are in the carb bowl, and make sure that the 17mm nut thats on the bottom of the carb bowl is tight

the kicker will take a while 2 get use 2, find the compresion release then kick

i believe so, probably sat for a year. it mainly leaking out the hole at the bottom where the screw is to drain gas out the bowl. i screwed that screw all the way in but gas still FLOWS out that hole, and i cant get the bowl off cause the screws seem to be stripped. and it doesnt always start after kicking it for about 30 mins, it might start once or twice buts its not consistent.. sometimes it idles. yesterday it didnt idle i had to continously rev it for the motor to stay on. on the carb there are two knobs at the top one on each side, what are they for. i know the air fuel screw at the bottom, but one do the other two do at the top. i turned the one on the left top side of the bike the other day. i guess im not sure what i should be trying to do first to get this quad running

I'd go ahead and remove the carb completely and go over it really good. Get it cleaned out and inspect the jets for clogging and to see what the numbers are.

The knob on the back side or intake side is the idle. I believe the other is where a Hot start is installed.

You may need to replace that drain screw, I hope it's that and not the bowl stripped out.

Kicking these motors over is an art, I learned the hard way. There's a sweet spot to kick it at which is basiclly TDC. When you find TDC you'll notice the lever will lock up. What you do then is completely let the lever back up and give it a swift from there and follow through all the way and it should start.


What mods does it have?

HONESTY, i dont know what mods it has. i bought it for 1300 bucks from the local police station, i know it has a fmf aftermarket pipe on back, a trailtech endurance computer installed. the starter relay and stuff is still there.k&n air filter.my foot is swollen i cant kick it again for awhile cause it hurts. i will try to remove the carb and go from there. i notice that i had smoke coming from the header pipe going into the engine. not sure whats going on..and the oil was overflowing from the oil reservoir when i took the oil cap off to check it.. i guess i need to just doing a full maintenance on it before i start to actually ride it. any info where i should go from here would be appreciated. and thanks to everyone who has replied so far. daddio cadwell and quadracer. i appreciate it. i am dying to ride, but i need to make sure its in good condition so it will last..this is my first quad and i am a beginner at riding. i didnt want to start off with a 450, but i could pass up a deal..

it seems my screws on the bottom of the float bowl are all stripped, they are not coming out. what should i do. buy a new carb.

did you pull the carb? Are the top(head) of the screws(bolts) that go into the bottom of the carb stripped? And you cant get them to come out? or are the actual threads stripped in the carb, if its the top u could work it out with a vise grip or plyers, other wise u got a few headaches approching!!

heres a tip to all mechanics..

the bottom bolts of the bowl seem to enjoy stripping out. what to do is to take a "dremel" or find some way to cut a slit into the bolts and use a screwdriver to take them out.. you can find replacement bolts for this at your local lowes or hardware store...

......I replaced mine with allen head bolts from ACE Hardware.

Since you got it at an auction, I'd go ahead and go over the basic maintnace procedures with it before riding it or even starting it.

Do an oil and filter change for sure.

Remove the carb and get it cleaned up and replace the stripped bowl screws and if you have to, just plug the drian hose with a screw for now.

Check the valve ckearences and do the cam mod while you're in there.

Clean the filter and oil it up. You should remove it anyways and let us know if it has an aftermarket billet intake of some kind.

Repack the FMF also because this can make it run rich and throw your jetting off.