2008 YZ450F cam chain problem

I have the opportunity to purchase a new white 08 YZ450, but after reading about the cam chain and tensioner problems I would like to learn more about this issue. My questions: Has the cause of the failure been identified as defective part(s)?

If so, has the replacement part(s) been redesigned to correct the problems?

After reading about this issue with the 08 YZ450 I would normally not even consider purchasing this bike but, the price is exceptional.

I searched a bit before posting this but found very little other than a few instances of the failure, and no real solutions offered to remedy the problem.

I have the opportunity to purchase a new white 08 YZ450, but after reading about the cam chain and tensioner problems I would like to learn more about this issue. My questions: Has the cause of the failure been identified as defective part(s)?

If so, has the replacement part(s) been redesigned to correct the problems?

After reading about this issue with the 08 YZ450 I would normally not even consider purchasing this bike but, the price is exceptional.

I searched a bit before posting this but found very little other than a few instances of the failure, and no real solutions offered to remedy the problem.

I have owned an 08 yz450 for over a year and this is the first time I hear anyone mention such problem. Where did you hear about that? My guess is you didn't find much "info" when searching about it is that there's really not a problem. I visit this forum on a daily basis since the 08 came out and have never seen anyone bring that up. It's possible that someone out of the thousands of people that have bought one had such failure, hardly a "problem" if you ask me. They are man made machines, so they're not perfect and at least one out of thousands might have some failure at some point. Now, don't get me started on the Honda valve issues, now THAT'S a real problem, and a well documented one at that. I would certainly not abstain from purchasing an 08 yz450 for a good price, they are awesome machines, extremely reliable. yamaha's are the most reliable when it comes to valves, cams, cam chain, etc.... Search this forum and you'll find a lot of posts about bikes going for years without even needing a single valve adjustment or having any sort of major malfunction, now, THAT'S reliability.

http://www.thumpertalk.com/forum/showthread.php?t=731051&highlight=2008+yz450

I came across this thread. What do you think? Serious or nothing to worry about?

I can attest to the reliability of my 2001 YZ426, I purchased it used 5 years ago and have done nothing more than good consistent maintenance, no serious problems other than the typical leaking fork seal or dirty carburetor. It has been and continues to be a "great bike". I really want this 08 YZ450, just want to educate myself a bit before I hand over the cash.

Thanks for your reply :lol:

The cam chain on my 2007 YZ450F jumped a tooth after approximately 55 hours. I was lucky that no damage occurred to the engine as it started just fine after putting a new chain and done the timing. Three of my fellow YZ450F riders had similar issues where the bike had become hard to start then had to open and repair.

When I looked at my old chain, it was not that much stretched but when you hang it you can see it crumbling, not smooth like a new chain. My guess is the cam chain tensioner is not powerful enough to un-crumble the old chain which eventually fails and jumps a tooth or two. To this point I do not know what is the best solution other than maybe replacing the chain and tensioner every 40 hours or so and keep your fingers crossed.

The bottom line, I believe that there is an issue with the Two-Cams Five-Valves design Yamaha has in its YZ450F and YZ250F.

Any more ideas?:lol:

http://www.thumpertalk.com/forum/showthread.php?t=731051&highlight=2008+yz450

I came across this thread. What do you think? Serious or nothing to worry about?

I can attest to the reliability of my 2001 YZ426, I purchased it used 5 years ago and have done nothing more than good consistent maintenance, no serious problems other than the typical leaking fork seal or dirty carburetor. It has been and continues to be a "great bike". I really want this 08 YZ450, just want to educate myself a bit before I hand over the cash.

Thanks for your reply :lol:

I wouldn't worry about it, seems like maybe just a bad small batch of bikes. If even that, since most of the bikes already had quite a few hours of use on them. I'd say 50+ hours is probably about time to change the cam chain, and maybe the tensioner for peace of mind. It's also about how the bike was used and by whom. It's obvious that even the best bike wouldn't last the same in the hands of a mellow trail rider as it would in the hands of a fast racer who's always bouncing off the rev limiter. $16 for a cam chain at 40 hours on the motor is pretty cheap insurance I'd say. 5 or 6 cases out of 1000's of bikes yamaha has sold wouldn't make me lose any sleep.

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