stupid yamaha!

[1fst400]

My buddie has a 04 yfz 450 that has been giving us some issues. Moastly me because I wrench it for him. So here is the issue.....

One day it was running and he said it started cutting in and out and then shut off. So I told him to cleen the carb out figuring the float was jamed or somthin. So I go over to pick his quad up for the practice the next day. Put the carb on the quad.

Heres wher it gets tricky...

quad starts up with good batery charge. But then dies just as before

Batery looses chage fast so we bump start it.
Quad dies, pops, backires any thing below like 3k. headlights Are on th whole time btw.


I figure the stator or flywheels is gummed up at this point. I take the stator cover off and the flywheel was slugy, So I cleened it well.

once together we bump start it and it does the same exact thing.

So at this point im somewhat stumped. So I hook jumper cables from his quad to a car batery.
Quad starts on its own but agin wont run anything below 3k.

So I say "skrew this pos im going to eat"
Eat dinner......
Go back to quad, this time with kids dad also helping a hand.
We disconnected the rectifyer (sp) or voltage regulator thing.
Put the jumper cables on it. quad sarts up, blows both headlight bulbs instatly and runs MINT!!
Took jumper cables off quad and it runs good, idles, reves all good.
But quad seems not to be making any power to charge the batery, However there IS power running to the burnt headlight bulbs.

Im stumed at this point. But it runs for however long the batery will last. So we are running it. let me know what you think it is.

[maxamillion]

My bros 06 yfz450 would always be a pain to start and would cut out on top end. Eventually it wouldnt start at all. I tried cleaning and checking everything before he finally took it to the dealer. They said the way he wired his kill switch (which was wired correctly according to the directions) caused his CDI to short out. They swapped the CDI out, rewired the killswitch, and now it runs like new again. I forgot the brand of the killswitch but I can check later. -Max

[joshyz125]

you said the battery would not hold a charge, some machines HAVE TO HAVE a fully charged battery to run correctly. Since you had the headlights on, with a bad battery, the stator was probably just barely keeping enough power to make it run with the lights on, you jumped it, which was to much for the headlights, now it runs better because it is able to produce more power to the battery, but it's not holding it, and still not quite enough to make it run the way it's suppose to.

I could be wrong, but it's worth a try.

[panteramatt]

I know the yfz uses a different charging system. Your supposed to run with th eheadlights always on or it sucks the battery.