04 450 won't do anything but idle!!

Will do, first thing in the morning. Thats why I was thinking back and noting that I added gas before checking the flow.. thus releasing the pressure.. but soon after that I took it down the road and it started doing it after a few good honks on the throttle... still going to try it.

decided to go outside and pull the vent hose off to check.. can blow through it easily, its on the right way, the ball is rattling around nicely. Can also blow into the tank and 'pump it up' and it blows the air back out nicely. wish it was that simple. don't want to buy another cdi box but if that what the general consensus is then I guess that what ill do

toys are expensive:(

tell me about it

anyone want to buy two jet skis, three fourwheelers and a dirtbike? jk I love my toys, not ready to part with any of them.

my R6 is my baby, haha

yeah wife made me sell my ninja, so I got the 450..

back to the topic,

Theres got to be another explanation I'm skeptical to buy another cdi they ALWAYS go out completely.. any ideas greyracer? guess ill start with checking over the electrical real thorough

You could blow through the vent hose from which end?

from the end with the rubber grommet that goes into the steering stem, come on greyracer you jump on the known problems take a guess you don't always have to be right

I too would say it is your CDI box. Electronics can act in many different ways. They dont ALWAYS go out completely. My friend had his go out on his 83 xt we could start it but it would run rough and backfire alot. So they dont always go out completely.

Another thing you could check it the TPS.

decided to go outside and pull the vent hose off to check.. can blow through it easily, its on the right way, the ball is rattling around nicely. Can also blow into the tank and 'pump it up' and it blows the air back out nicely. wish it was that simple. don't want to buy another cdi box but if that what the general consensus is then I guess that what ill do

Do you know someone with another YZ450, similar year? See if you can borrower another CDI to test your theory before buying one. I'd hate to see you buy one and find out that it wasn't the problem, then you're out some money and still have the same problem.

would an 05 YFZ450 box work?

the quad cdi wont work, it has to be from a yz. the wr unit wont work either

which year has the best timing curve? I think I read somewhere that the 05 one was the best.

The '05 actually stunk. It had the same cams as the '03-'04, but was universally criticized as being (relatively) gutless. The '06 was probably one of the best, but I don't know whether it can be interchanged.

Intermittent problems are always the most "fun". I double-checked you on the vent hose because your answer wasn't clear, and your reference to the tank's ability to release pressure suggested a lack of understanding that the problem with an inoperative vent system is that a vacuum forms in the tank, slowing or stopping the fuel outflow at the petcock. Just checking.

My first next step would still be to run it until it acts up, and then open the cap. Why? Because it's common, and it's simple to test, and cheap to fix. Remember that electrical parts are non-returnable.

If it isn't fuel, then while the bike is in its semi-failed state, check the stator. The manual does not give specs for it, but you may want to back probe the two circuits while the engine is running right, take an AC voltage reading of the output, and compare that with what it does when failed.

The second thing to check would be the coil resistance.

It seems fairly likely that if it turns out to be electrical, you will end up with a new CDI. This time, though, go with a Vortex, is you have to have an aftermarket product, or stick with OEM.

thank you all for helping out.

I have the shop manual so the resistance testing is no problem. Measuring the AC voltage shouldnt be a problem either, just a matter of finding some pointy leads for my voltmeter to stick in the connector while its running. Thanks for a bit more direction and will def. post back what I find, although it may take some time.

Thanks mikedabike for helping a guy out. Letting me borrow his spare cdi free of charge!:lol::lame::bonk:

how did it work out

It's unlikely that the CDI has traveled the 2600 mile distance between Mike and Florida just yet.

im sorry i didnt know who or where he was

PM'd tracking # should be there Friday.

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