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Wiz636

Timing Chain Discussion

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I've been thinking about the people that have reported their timing chain jumping time and was trying to come up with some type of correlation between these events.

I'm having a hard time wrapping my head around it just being a random occurence based on a 'perfect storm' condition manifesting itself.

We know it happens..recently I've seen/heard of it happening at 55 hrs and 30 hours. No reports of faulty tensioners. It has never happened to my bikes but I change mine at 50 hours and there is an easily observable difference in chain length between the new/old cam chain, but I have never seen any kinking or even binding.

On the failures, what, if any, other observations were made? That is, scoring on the cam journals? Were the valve clearances in spec? Oil change frequency? Condition of the cam chain 'sliders'? Any other thoughts?

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My bike was at 55 hours as you know. All of them pretty hard hours. I compared the old and new chains and the looked to be the exact same length, but the old one was a little bit sticky/binding, but only a little tiny bit.

One other thing that might be unrelated, I've always used Yamalube 10w40, and the guys at my shop say they use maxima oils so I switched to that the night before my chain skipped. I'll be going back to Yamalube for the peace of mind. I really don't think the oil change caused the problem.

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Jason, I noticed that you had just the slightest scoring on the cam journal on the exhaust cam cap...not much but it was there. What is your oil change interval?

I use Amsoil MCF 10w-40 full synthetic and change it at six to ten hour intervals depending on whether I am racing or playriding. At 110 hours I have no sign of scoring in my journals.

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In every instance I have personally seen of an '06 or later engine jumping time, and in all of them where I've been able to gather this much detail, the chain has had several stiff links. IMO, the chain is at fault. The condition MAY be lube related in some way, but I lean toward doubting that.

http://www.thumpertalk.com/forum/showthread.php?p=8615972#post8615972

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I generally change it every 2 rides. Sometimes every 3 if they are short trail rides, so probably every 5-10 hours. I use Yamalube 10w40.

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In every instance I have personally seen of an '06 or later engine jumping time, and in all of them where I've been able to gather this much detail, the chain has had several stiff links. IMO, the chain is at fault. The condition MAY be lube related in some way, but I lean toward doubting that.

http://www.thumpertalk.com/forum/showthread.php?p=8615972#post8615972

My chain didn't have any links that were completely stiff, but if you fold it around enough times, every once in a while you can get one to bind up, but it comes un-stuck almost as easily.

I agree that the oil was probably not the problem, but I've never had any issues while running Yamalube, so I'm going to continue using it.

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From what I understand there was a bad batch of timing chains that were made and that some of these had the unfortunate ability of stretching too quickly and this caused the chain to jump timing. Especially in high RPMs and over reving. As part of regular maintenance I suggest checking and/or replacing the timing chain and for that matter the tensioner (even though these seem to be bullet proof in most cases). This is low cost insurance as far as I am concerned, usually under 50 bucks for the parts. Not doing this is a going to cost a lot more than 50bucks if your bike is one of the ones that has the bad chain.

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I'm willing to accept the "bad batch" theory as a concept, but only in part, because of the defective chains I have personally handled, none have been significantly longer than the new chain when compared to it directly. All of them were kinked, however, and as I said in the post I linked to, this is what I believe causes most of the problem.

As to the "batch" itself, it appears to span the range from mid '06 to mid '08. The kinking and failure issue also appears to involve only a fairly small, but still unacceptably large, percentage of the total bikes built, and was the worst though '07.

My advice would be to replace the chain regardless of anything, just for the security.

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does this pertain to my '02 yz426f as well? i'm afraid to even start it until my cam chain gets here. it's been really freaking me out lately cause of all the stuff i've been reading about timing chains etc...

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As to the "batch" itself, it appears to span the range from mid '06 to mid '08. The kinking and failure issue also appears to involve only a fairly small, but still unacceptably large, percentage of the total bikes built, and was the worst though '07.

My advice would be to replace the chain regardless of anything, just for the security.

Is it possible Yamaha still has this "bad batch" of timing chains available to purchase?

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Is it possible Yamaha still has this "bad batch" of timing chains available to purchase?
From experience as a automotive dealership technician for over 20 years, yes, it's possible, but at this point, I'd say it was less likely.

And no, it does not apply to either the 426 or to the Gen1 450's, apparently, even though the 450's in question both use the same chain.

It either has to be a vendor or "bad batch" problem, or something about the Gen2 engines delivery of oil to the chains.

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My 07 jumped after only about 10-15hrs...Yes, the chain had stretched (didn't have any kinks that I could tell, looked new), and I was told by a respected mechanic that the tensioner was at fault (he also said that it was VERY rare for that to happen and was personally his first case of it)...I have since inspected the old compared to the new tensioner and the old one that failed has noticeably less spring to it...Right before this had happened, a friend had fried my clutch (treated it like his streetbike and used the clutch for every gear change, and let the bike idle for long periods of time)...So my opinion is that the extreme heat cycles (most of those few hours were put on in dunes) practically melted the cheap spring inside the tensioner, and made it loose it's springiness, which in turn allowed the cam chain to stretch prematurely (I'm assuming it's about the same quality, if not less, as the stock drive chain, which I had already replaced)...

I think it's an issue that the cam chain is as cheap as the drive chain, accept most people change their drive chain right away...

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I have 175 Hrs on my 07 bike , this winter i was planing on doing the cam chain, my dilemma is should i change the tensioner as well?

Do i buy stock or an aftermarket chain?

the bike starts first kick, when hot ,when cold 3 kicks, valves have not moved from new. I check valves every 20hrs. and the timing is spot on, showing no chain stretching.

i know what a stretched chain looks like and have seen the slop in the cams, timing with my 01 WR 250f

i ride all trail , no track. change oil with Maxima , every 7-8 hrs.

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In Canada the stock chain is $35, the tensioner is $82 from Yamaha Canada

http://partsfinder.onlinemicrofiche.com/yamahagenuineparts/Yamaha_OEM/YamahaDB.asp?Type=13&A=399&B=5

aftermarket chain canada $62

http://www.gnarlyparts.ca/product_info.php?cPath=5978_3774&products_id=53963

would this be a good chain to get?

your us prices are $13 chain , $37 tensioner

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From experience as a automotive dealership technician for over 20 years, yes, it's possible, but at this point, I'd say it was less likely.

And no, it does not apply to either the 426 or to the Gen1 450's, apparently, even though the 450's in question both use the same chain.

It either has to be a vendor or "bad batch" problem, or something about the Gen2 engines delivery of oil to the chains.

Would it even be worth buying a cam chain for a 2009 model to try to eliminate the possibility of receiving a "bad" chain, or would it most likely not matter as they share the same part number?

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Are the majority of these chains going bad on mostly 450's? I would think that normal wear and tear would stretch the chain not make some links stiffen or kink up? What makes the chain kink up like a drive chain would? Improper oil? My 05 chain was replaced around 40 hours with no noticeable wear and tear. Is there a design/engineering problem if only the 450's are having these issues?

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I'd hate to think how many hours I had on my chain. I've had my bike since early 06. i just put a chain on only because I changed to a heavier FWW. It was slightly longer than the new chain. It was time. The oil I run is Spectro 10w 40 semi synthetic. I've been running this oil in all my thumpers. Luck, I dont know, but its what I use and have had real good luck with it with frequent oil changes.

I dont baby the bike, I bought it to ride hard and have fun.

But as easy as it was to change the chain, I'll do it more often. Its cheap insurance.

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Are the majority of these chains going bad on mostly 450's? I would think that normal wear and tear would stretch the chain not make some links stiffen or kink up? What makes the chain kink up like a drive chain would? Improper oil? My 05 chain was replaced around 40 hours with no noticeable wear and tear. Is there a design/engineering problem if only the 450's are having these issues?
You ask a lot of questions for somebody from Arizona. :busted:

Morse chains being a stack of plates as they are, any galling between plates or any sort of significant debris build up between the plates can take up all the available clearances between the plates and wedge them between the pins, making them stiff. Why exactly this should occur in certain bikes and not others is not very clear, really, at least not at this point.

The timing chain problems have always been reasonably rare in 426's and '05 and earlier 450's. The fact that the failures became more common at the same time there was a redesign of the engine is what raised the question of oiling, but there isn't anything particularly different about how the chain is oiled in the Gen2 vs. Gen1 engines. So was it a change of vendor? A bad batch? I don't pretend to know. But it is intriguing.

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