I recently replaced the cam chain and tension on my 2006 (and readjusted valves while i was in there), after the previous owner left some foreign object in the top end (I'm guessing wire to tie up the values during adjustment). Anyway, long story short, just recently the engine seems to be making noise, and its become louder over the past few rides. I know the sound of the engine well enough to know there was an audible change, which sounds like a pinging, rattle sound, near the top of the motor.

So, I tore into it today, and found that when I took the tensioner out (fully extended) and placed it back inside the housing, I had little or no resistance. There is lots of slack in the chain from what I can tell, and has most likely caused the engine to be off timing by 1 tooth (hence the audible change in noise would be my guess). So the question is, 1st HOW on earth could the chain be stretched so quickly? I had maybe 3 or 4hrs since the replacement (oem chain). 2nd could it be the plastic tensioner internal slide wearing out (and how do i know if its in need of replacement)? 3rd what chain can i buy that will last?

When i called the dealer to complain, he said they wouldn't do anything about it since it wasn't done by a service tech. As far as Im concerned, this is my 2nd run in with cam chain and tensioners, done buying OEM.

http://www.bigboreth...tensioners.html

APE Jay, on 10 May 2012 - 11:26 PM, said:

you really think that is my end all, answer? I have a new tensioner, less than 5 hours on it.

There is nothing wrong with OEM cam chains. If you have actually measured your cam chain with 3 or 4 hours and compared the dimensions to another cam chain and it has stretched, I'd consider that an isolated incident unless there is something else going on.

Are you saying you can compress the tensioner by hand or you can install it fully extended and it does not have much tension? Do you have both of the chain guides in there? If the previous owner left mystery pieces in the motor when he worked on it, there's a good chance he did not put all of the parts back in it.

Edited by RHanson94, 11 May 2012 - 09:58 AM.

Im taking the chain off today and sizing it up with an OEM from a local shop here.

Ya that was confusing wording there... I can't compress the tensioner at all (when its fully extended). But i can, as you mentioned, install it when fully extended and find there is not much resistance when pushing the tensioner back into the engine housing. Both guides are there (although they could be worn??), I have a full pdf manual for the bike and everything is there. Ive rebuilt motors before, I'm fairly confident in knowing my way around engines, Im just extra picky because I was close to having my motor detonate last time.

A friend of my suggested that the crank cam teeth or cam sprocket could be worn.. bike has about 40 hrs on it total.

thanks for the responses

Make sure the chain guides arent broken. Ive got one on the bench right now that had the chain so kinked up that it actually broke the case where the white chain guide foot sits.

ill check it out this afternoon. has anyone seen the crank teeth wear down? Ive heard of guys have 100-200hrs on these motors without full bottom end rebuilds... I can't image the teeth would wear so fast!

Id bet a 12 pack nothing is worn. Something is broken. The black guide can come out the top once you've got the flywheel off. If the white one is broken you've gotta pull the head to get it out.

fingers crossed. ill check it this afternoon and let you guys know.

how many run manual tensioners?

Alright, I'm an idiot. Totally forgot that my cam chain was actually never replaced (noticed when i looked at saw an "M" or "W" which I believe is Wiseco)... I had bought one to measure up against the chain I had, but returned it to the dealer. So im almost positive its the chain.

Go OEM or after market? Brands? Preferences?

Thanks guys

I would go OEM for the cam chain. They can be found fairly cheap online.

yup, just get an oem cam chain. I just installed a tokyo mods manual cam chain tensioner on my 08 tonight after replacing intake valves. Have an APE mcct on my 04. The tokyo mods looks trick, but the APE is MUCH easier to set the tension on.
With only 40 hrs total (true 40 hrs - i rode 40 hrs in the last 2 months), i find it hard to believe the cc is worn, especially running a stock cam chain adjuster. If you tighten a mcct too tight, you could wear stuff out faster but stock stuff??

ONe way to determine the cc is worn, is you can't get the cam sprocket mark and cam tower mark to line up properly.. the cam sprocket mark is either just below if 1 tooth retarded, or if done right, the cam sprocket mark will be above the tower mark because the chain is worn.

Edited by MELK-MAN, 11 May 2012 - 09:02 PM.

MELK-MAN, on 11 May 2012 - 08:59 PM, said:

The TMods mcct is nice looking. I would have bought one if they weren't a lot more then the TT one. The one thing I don't like about the TT is that the all thread sticks way the hell out. On my bike there is about 1" of thread that is not needed. I assume it's because it it universal....

I was just thinking about the timing marks and how they would line up at if the chain were stretched. My intuition was right. I put a new chain in when I did my piston and thats what got me thinking about it.

Edited by mrmoto35, 11 May 2012 - 10:04 PM.

mrmoto35, on 11 May 2012 - 09:15 PM, said:

as your cam chain wears, your gonna need some of those threads sticking out

And just to clarify, the ape mcct i was refering to was the cheaper model that has a 16mm+- adjuster nut on the end, you can easily move it with your fingers and "feel" the free play in the cam chain. The Tokyo mods one or the APE one that looks like the tokyo mods with a small flathead screw adjuster, is not as easy to determie if the cam chain is too tight or too soft.

Edited by MELK-MAN, 12 May 2012 - 06:34 AM.

MELK-MAN, on 11 May 2012 - 08:59 PM, said:

40-50 hrs, bought the bike used so who really knows right?
since I've owned it, thats what I guess it has.

If you read the first post, I explained the cam was stretched when a large piece of wire was caught in the chain an wrapped around the cam shaft teeth (previous owner mind you). This caused it to stretch pretty fast, and also destroy the CCT. I thought I had replaced the chain last year, but didn't after thinking it didn't look stretched.

ill be looking into a MCCT in the future, for now I have a new stock one. I bought an OEM chain yesterday.

Thanks for the ideas guys.

MELK-MAN, on 12 May 2012 - 06:32 AM, said:

Oh yes I will need some. It would be really cool if you could mark it to show when you had reached the service limit on the chain

The reason so many advise using the mcct is that the acct works good until it doesn't. When they fail they usually cause a great deal of damage to the motor, to the extent that you end up rebuilding the entire motor because the chain skips teeth, the valves hit the piston, crank takes the hit full force and so on and so on...

If you can swing it I highly suggest getting a mcct. the TT store sells a really nice one for around $50.00

Bigace109, on 11 May 2012 - 02:16 PM, said:

The OEM chain is made by Borg-Warner. The Wiseco is made by...China probably. Dunno. But I still think there's another problem beyond the chain itself.

Its not impossible for the black guide to be broken off at the anchor bolt allowing the adjuster to extend all the way and still not do much.

Seems like my ACCT is all the way out and it barely tightens the chain. I've been noticing a rattle at certain RPM and throttle load. I have previously replaced the piston so it's not that rattling.

So I am replacing the chain and guides. I'm at the point where it looks like I need to pull the flywheel off. 2005 CRF450R by the way. How exactly do I get it off? I haven't tried yet as I don't want to bugger anything up.

I did find a wire "bread" tie down by the oil pickup, oops by the last guy that was in there.

At least on the flywheel side, the it feels like I can move the crank/flywheel radially (up and down, not in and out) a few thousanths. I'll throw an indicator on it to see how much it actually is. There doesn't seem to be any axial play in the crank. I have no idea how many hours are on it as I bought it used.

Thanks.

Johnsinski, on 15 May 2012 - 06:51 PM, said:

i see a manual in your future.. and a $15 flywheel puller.