04 YZ 125 blowing up?

[SirFallsALot243]

I was talking to this person today who just got a 2004 YZ 125. Soon after buying it, it basically blew up. The plastic inserts (crank stuffers) in the crank melted after the bike overheated. The crank went through the cases. Its a $950.00 fix. My question is, would it be possible to replace these inserts with metal ones? Do they make metal ones? The make metal crank stuffers for 00-03 yz 250's. Have these always been plastic or could he use crank stuffers from an older year bike that has metal ones? If he gets the bike fixed and overheats it again, it will happen all over again with the plastic ones. Any ideas?

Man, im never gonna get a yamaha....

[ddfh_4_life]

Dude, thats my friend...Thats keech. LOL, small world.

[Thump_This]

problem is. why did the bike overheat in the first place?

[MATTXR250R]

Originally posted by 2003YZ125
problem is. why did the bike overheat in the first place?

EXACTLY!!!

[ddfh2x]

Yea this is my bike, not even 20 hours and I need to put another grand into it. The dealer called today to give me the bad news. They think that i over reved and that caused the crank to blow. I dont see how i could have managed it to rev it that high just riding around in a feild. Some thing tells me that they are a bunch of idiots, and also is 8 hours of work worth $480? I didnt give them the go ahead to work on it so there is still time to pull it out and go somewhere else.

[ddfh_4_life]

The dealer says he over revved it. But we found A LOT of coolant in the oil, so we think there was a faulty seal. The bike doesnt have more then 10-15 hours on it, and he was getting into 3rd gear on about 1/8th mile of feild including a slick turn which you have to slow down for. If you over rev it, it should just over heat and stop, not kill the engine. If yamaha was smart they wouldnt put plastic pieces inside an engine that is supposed to be ridden hard.

[ddfh_4_life]

Keech, if ya think about it, I doubt theres more then 10-15 on it. A little at cat swamp, maybe 6 hours total, maybe 2 or 3 in the feild behind your house, 20 minutes at the race if that, and some where the bike died...I think they are a bunch of idiots, they didnt even know what the inserts where, and they didnt even know what a durablue axle is. I say you yank it, and we work on it.

Btw, I got scared when I saw the ddfh and then a yamaha sign over it...but then realized it was you...Lol.

[MATTXR250R]

Originally posted by ddfh_4_life
If you over rev it, it should just over heat and stop, not kill the engine.

You are DEAD WRONG my friend. Go out and over-rev your CR125 and you will see that it doesn't just overheat and stop. When you over-rev the engine you are putting more stress on teh piston,rod,crank that it was mean't to handle and things get ugly quick. He could have simply been on the gas and hit down on the shifter with his left foot on accident and with the clutch out the RPMs went soaring.

[Dell30rb]

The funny thing is that you cant over rev it. All bikes have a rev limiter and they are designed to operate safely all the way up to the rev limiter. Try speaking directly to yamaha. Get a rep to look at it, not just the dealer.

[Dell30rb]

well, matt could be right, it is possible to over rev it by accdientally clicking down a gear.

[MATTXR250R]

Ren...Rev limiter will NOT work when downshifting.

[MATTXR250R]

I know I have done it a few times on my XR right after riding the CR....you sit,stand in a different position on the CR and when I get on the XR I have to move my left foot over more than I do on the CR to clear the shifter and I have knocked the XR down a gear and the RPMs went screaming but I got the clutch in right in time.

[Thump_This]

mattxr250 is right. go drive you car and drop it from 5th gear at 100mpf into 2nd gear and watch the parts fly ! same thing on a bike. it will cut the spark but the crank and piston will still have to spin at HIGH speeds.

[MATTXR250R]

BTW Ren...hows the 250F doing so far? I hope its ripping the ground up good for ya

[SirFallsALot243]

But could that cause 1000$ worth of damage? I revved my '74 to the moon when i was just learning. I rode around full throttle in 1st at the beginning and that never happened. Ive down shifted by accident also. Ive never had my bike blow up. That shouldnt happen.

[ddfh_4_life]

I have over revved my cr80 and it stopped, Let it sit for about 5 minutes and it fired first kick...I know over revving it can kill the engine, but this just isnt the case. The dealer said all the internals in the topend were good. I dont think the rings are, but whatever..I know for a fact he didnt downshift...And its pretty much impossible. Were not talking riding hard, were talking going straight doing a wide turn and turning around to do the same. No jumps or bumps.

[Thump_This]

what is on the bike? what heat range plug? is it jetted? what premix ratio were you guys running? another other variables i left out ? oh, elevation ?

[ddfh2x]

I kno i didnt down ****, it happened about 100ft out of a corner just after I put into third. Also I didnt mention that earlier in the day it was idleing alittle higher then normal, not extremely off but definetly higher then normal. Could that have had anything to do with it?

[MATTXR250R]

Ineedabetterbike.....I wouldn't cost you 1,000$ for a new crank,rod kit,and a new set of cases...its when you take the bike to a shop to get it fixed is when that will easily turn into 1,000$...do the work yourself if you can.

[SirFallsALot243]

But i didnt damage anything, it still ran fine. Granted it doesnt run anymore, but thats just because the float is stuck. But theres nothing wrong with the crank, and i revved it incredibly high. Its a 1974 and its on its original crank. (hard to believe, but true)