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I'm done with this!

By Danielson,
in YZ400F/426F/450F/450FX

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Danielson

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Just finished a complete top end rebuild. New cam chain, cylinder, gaskets, piston! This was all due to an anomalous noise that started at random on my 07 YZ450 that I bought used. Bike had 22 hours on it when I bought it and at 36 hours the abnormal noise started (clunking..clicky..almost rattly noise). Well I finish the rebuild today (even after my first parts package from Rocky Mountain ATV/MX fell off the UPS truck and a landscaper decided to keep for himself a week ago..another story) and started the bike up for a phase 1 break in run and wouldn’t you know the same noise that was positively identified as piston noise by a "mechanic" previously prior to the rebuild was still very audible. So it looks like a complete bottom end tear down and rebuild is needed. I’m not comfortable with that level of maintenance and now don’t have the disposable funds to even attempt it after dumping money into a fresh top end (which it did need also). Just a huge let down after putting in all the time and effort into removing the motor, cleaning, rebuilding, installing, and now no pay off. I feel like trying to save money by doing the work myself has not paid off.

Just wanted to rant. ?

P.S. to Jose Martinez in Rialto, CA, I hope you have fun with my $400 worth of YZ parts that “fell off the UPS truck”.

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426 NOOB

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Just finished a complete top end rebuild. New cam chain, cylinder, gaskets, piston! This was all due to an anomalous noise that started at random on my 07 YZ450 that I bought used. Bike had 22 hours on it when I bought it and at 36 hours the abnormal noise started (clunking..clicky..almost rattly noise). Well I finish the rebuild today (even after my first parts package from Rocky Mountain ATV/MX fell off the UPS truck and a landscaper decided to keep for himself a week ago..another story) and started the bike up for a phase 1 break in run and wouldn’t you know the same noise that was positively identified as piston noise by a "mechanic" previously prior to the rebuild was still very audible. So it looks like a complete bottom end tear down and rebuild is needed. I’m not comfortable with that level of maintenance and now don’t have the disposable funds to even attempt it after dumping money into a fresh top end (which it did need also). Just a huge let down after putting in all the time and effort into removing the motor, cleaning, rebuilding, installing, and now no pay off. I feel like trying to save money by doing the work myself has not paid off.

Just wanted to rant. :ride:

P.S. to Jose Martinez in Rialto, CA, I hope you have fun with my $400 worth of YZ parts that “fell off the UPS truck”.

are you sure that the noise is abnormal? Was the noise never there and then all the sudden started? Yzfs are the loudest freakin 4 strokes motor noise wise. My 426 makes all kinds of scary noises, but they have always been there. As far as i am concerned ups should be held responsible for the screw up. It is their responsibility to get a signature for large $ orders. Sorry to hear it man.?

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Danielson

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Yeah the noise is for sure abnormal. I have a skid plate and hear all the usual loud engine noises, the abnormal noise started on an uphill run about 1 hour into a medium to hard ride. It now makes the noise once the engine is warmed up, well almost immediately now after the engine rebuild. UPS and Rocky Mountain were both super cool. Rocky Mountain shipped out a replacement order as soon as I called them with free overnight delivery. They are a class act. As for my parts from the thumper talk shop....well I am still waiting as they have dropped the ball and not even come close to meeting the advertized 4-7 day shipping. It's now day nine and I only have a tracking number for a partial shipment.

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Danielson

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Yeah, I was supper surprised at how great thier customer service was. They assigned me a case manager to ensure I got all the parts I needed. I found out the next day I needed a separate part and they gave me a 10% discount and more free overnight shipping.

Mr. Grey if you read this, do you live localy (Murrieta, CA) and could maybe help me through a bottom end inspection and rebuild?????

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Proficient

426 NOOB

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Yeah, I was supper surprised at how great thier customer service was. They assigned me a case manager to ensure I got all the parts I needed. I found out the next day I needed a separate part and they gave me a 10% discount and more free overnight shipping.

Mr. Grey if you read this, do you live localy (Murrieta, CA) and could maybe help me through a bottom end inspection and rebuild?????

I believe ive read that gray lives in san diego.

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Grand Master

ubu

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I'd be peeved, too. But 36 hrs sounds pretty low for an engine failure on a YZ, based on posts in here. Unless it was never maintained.

Was it running poorly? What did the cylinder, piston, and head look like when you took it apart? Was anyhting out of spec?

I have no idea how anyone could diagnose piston noise on one of these (they are just plain noisy) but I'm not very experienced.

Could be something in the trans, too.

About the shipping woes... I've noticed not many places are stocking parts. Probably because not many are buying, riding, or sevicing much right now. A friend is a tech at a local dealer, and he is slow. Shoot, turnaround on my forks was half a day because there was no other business. Just last week I decided to do a cam chain and Motosport had a 3-5 day backorder. Wouldn't you know it, my local dealer just got 15 of them in stock, and the price was better because I didn't need to pay shipping. Try buying local. It might be in stock. Prices CAN be competitive. And, the dealer will have to eat the shipping if something gets jacked up. My latest order was only a 2 day wait.

Just my $.02

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Grand Master

ThumperKid250F

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i remember when i bought my 06 and i put my skidplate on it and i thought my motor was blowing up:lol: pull your skidplate off and see if the noise changes at all and if it does put the skide plate back on and get some rubber strips and put them on your framerails were your skidplate hits and the noise will go away..

good luck ?

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dvn

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i remember when i bought my 06 and i put my skidplate on it and i thought my motor was blowing up:lol: pull your skidplate off and see if the noise changes at all and if it does put the skide plate back on and get some rubber strips and put them on your framerails were your skidplate hits and the noise will go away..

good luck ?

The noise won't go away. It will be reduced, but it won't go away. I have rubber mounted my skid plate as well as lined it with bedliner spray and using skid plate foam and it's still noisy. Better, but noisy. I guess it's just the nature of the beast.

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ThumperKid250F

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The noise won't go away. It will be reduced, but it won't go away. I have rubber mounted my skid plate as well as lined it with bedliner spray and using skid plate foam and it's still noisy. Better, but noisy. I guess it's just the nature of the beast.

yea it is, mine makes noise too.. my buddys 05 with the steel frame is even louder than my 06 too..

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Danielson

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Thanks for the super technical skid plate removal procedure but I don't think that will help as I have had the skid on the whole time. Unless somehow it just decided to amplify a previously unheard noise mid ride.

I think you may be right iamcanadain on the rod or crank bearing. Does anyone know if heat discoloration on the crank where the rod connects is normal???? I noticed it during the rebuild.

P1040556.jpg

P1040560.jpg

It also looked like the previous owner did a complete desert trip without an air filter due to the dirt stuck to the top of the piston.

Edited by Danielson
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Enthusiast

JandJ07

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I wouldn't rule out the skid plate just yet...if a rock got wedged between it and the engine "mid ride" it could easily have instantly appeared. I'm not saying thats for sure what it is, but it is a simple enough check. Have you tried removing it yet?

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Danielson

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I wouldn't rule out the skid plate just yet...if a rock got wedged between it and the engine "mid ride" it could easily have instantly appeared. I'm not saying thats for sure what it is, but it is a simple enough check. Have you tried removing it yet?

Yeah, after the ride when the noise started I removed the skid and washed the bike. This is a "you engine is going to f*^#ing blow up soon" noise. It's the sound of a failure coming hard and fast.

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