A good buy??? 03 450 w/ top end damage

7 replies to this topic
  • crazyadam

Posted April 27, 2004 - 05:49 AM


I am looking at an 03 yz 450, with 1 bent valve, and a bad head. needs a new head, cam chain and tensioner, intake valve, or valves.

I guess the chain "slipped" or something and whack,
I don't mind fixing it, but was wondering what I should pay for it? Or if anybody knows what else I should replace or inspect?

bike has gytr exhaust, pro tapers, an extra set of tires, and a few other goodies.

ANY opinions will be appreciated!


thanks again everyone.

  • Satch0922

Posted April 27, 2004 - 08:09 AM


Saw that one on E-bay. What you have to ask yourself is this....if the bike was defective or not properly maintained. Your rolling the dice. Let's put it this way...if it was repairable the guy wouldn't be will to take a big hit on the resale value.

  • sirthumpalot

Posted April 27, 2004 - 11:47 AM


The most common reason for a slipped timing chain on a 4-stroke is a worn drive sprocket (crank sprocket). When the oil is not changed on time this is one of the first places to wear. So after you figure out what you want to believe as to WHY the chain slipped, ask yourself these questions:

<ul type="square">
[*]If the cam chain drive sprocket is worn, was the bike grossly neglected, or does it just have mega miles on it (neither is good!)
[*]Can you replace the crank sprocket without replacing the entire crank half (is it pressed on or part of the crank half)?
[*]In either case above, what else on the bike might be getting ready to die?
[*]What else on the bike was neglected? Was the fork oil ever changed? The linkage ever greased? etc...
Personally, unless the price is very good and you're going to use it for the other parts, I would avoid it.

  • aford541

Posted April 27, 2004 - 08:33 PM


Price the parts, you may change your mind.

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • Hamish

Posted April 28, 2004 - 12:52 AM


you can add piston and probably barrel to your shoping list.
A bent rod is even a possible. You'd wanna get it pretty damn cheap!


  • bigwhitediesel

Posted April 28, 2004 - 05:35 PM


My '03 was fixed for the same exact thing. Thank god for extended warranty. $2023.02 Parts. $884 Labor.

  • bigwhitediesel

Posted April 28, 2004 - 05:48 PM


I had my entire top end replaced. After 1.5 hours of break-in, the intake cam gear slipped again. The camshafts ride on the head, no bearings. The head had been at the low end of tolerance, while the cam was at the high end. After riding for a little bit, the head expanded (heat), and basically clamped the cam, therefore causing the gear to slip (pressed on), throwing the valves out of timing, and the piston slammed into them.

Piston rod bent, Piston broke, valves bent, head cracked, the list goes on. But the motor was new. So that bike may not be damaged due to neglect.

  • crazyadam

Posted May 18, 2004 - 02:28 AM


I got it!! I sent the head to www.motoxtech.com and for less than 125.00 he will have the head in "new" condition!! ALL other parts that I needed, including a new tensioner, and top end kit,..... 225.00....

So.. 03 450 up and running, for about 3200.00, with a grand in extra parts, tires, filters, guards.....

I'm stoked!

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