Motor problems!! Please HELP!!

[bad01300ex]

Ok well tonight i was out at the track to race and i noticed (well i noticed it about 2 practices ago) that my motor was rattling, during practice i thought it was my chain and it needed lube or something, but then i still heard the rattling when i wasnt rolling, just revving it up.

So i thought maybe something is just rattling around a cable or something, so we had our few laps of practice and then it just started to get more on my nerves, so i went around and talked to these other guys and got a few people over to listen to it, and it was my motor.

At first we thought it was the valves rattling, but then this other guy came over with a socket extension and put it up to the motor and listened too it and realized it was coming from the bottom end, so now everyone is saying its the bearings or something and i could throw a rod!!

So i wasted 30 bucks tonight and didnt race either moto, kinda sucked, but what do you guys thing about my motor?? anyone else heard this in theres?
Any suggestions??

Hmmm. I heard some of the 04 YFZ's had bad crank bearings. They may need replaced or something. Take the bottom end apart and check or take it to a dealer

hope that helps

[yamablaster24]

sounds like your crank bearing is goin bad some of the 04s had bad one from factory like said before. Hopefully its under warranty. If not tear it down to bottom end ifyou know what ur doin and replace it.

[bad01300ex]

Yep if the crank bearing is the problem then the only option i have is to tear it down myself, anyone recomend a good repair manual?? Im gonna have my friend whos a mechanic help me out.

[yamaguy]

The good thing is now you can put an 06 Crank in it and bump it up to full 449cc:) :)

[Ride1Rob]

If you have a skid plate check your screws to make sure they're secure. Mine recently just started rattling and was sounding like my motor was coming apart. Retightened it and it's gone... Did that also one other time b/f. This time I used an extreme lock tite on it so hopefully it won't happen again.

[SRH]

Originally posted by Ride1Rob
If you have a skid plate check your screws to make sure they're secure. Mine recently just started rattling and was sounding like my motor was coming apart. Retightened it and it's gone... Did that also one other time b/f. This time I used an extreme lock tite on it so hopefully it won't happen again.

yeah same here if i punch the gas on mine it will rattle like crazy im like aww ****, sounds like my motor, but i was aware skids do that but still sounded just like inside my clutch cover, so then i put my hand on the bottom of the skid and hit the gas and there wasnt really any rattle...my skid is tight, but when you bend them by landing on rocks etc they might contact the frame just a hair when it vibs and you get the rattle noise, or u could have a small rock wedged in there somewhere

i think if it was my crank rattling it would of went last night when i raced 2 motos plus practice , i was running the motor hard too

let us know what you find out

[bad01300ex]

well took it to yamaha dealer, guy there said it didnt sound like the motor, he said maybe piston slap but not really sure, he said these things just vibrate like hell and make alot of noise if it isnt smokin or runnin bad he said not to worry too much, but keep an ear on it.

So i went to practice wednesday and it ran great, other than my dead battery:mad: (got resistor kit and ytz10 battery on the way:D )
Me and my freind deciced it has to be a loose bolt, so im gonna look all over the quad and find out what it is.

My skid plate is stock too btw.

Hopefully is not as bad as i thought

Thanks for your help

[Ride1Rob]

Also check your motor mounts bolts. My bolts that bolt to the frame as well as the long one that goes through the front of the motor to the mounts were loose. Over time those things can't take all that vibrating. Glad that it wasn't your motor though;) .

[MAaudioX10]

Yeah, don't worry about it until it gernades.

[snox31]

i know of a yfz that was starting to rattle so he cut the oil filter apart to see if there is any metal and there was.He tore the motor down and it was the bottom rod bearing starting to go bad.He found it in time so all he needed was a rod kit and not new cases and all the other parts the blow apart when the rod seizes to the crank and breaks.I would look into it a bit more ya might save alot of money.

[400exrider36]

my engine rattles too, but it was only during the few times i rode double. not sure what it is...

[snox31]

i saw in the owners manual that you are not supposed to ride double on this quad :D just messing with ya .was it a fat chick on the back ?

[400exrider36]

haha no just fat friend:rolleyes: