Cam chain way way to loose-opinions required!

So this is for an 2007 RMZ450.  Ya ya, not a honda!  Wish it was.  Posted this in RMZ pages...no takers.  Perhaps Honda guys are smarter than Suzuki guys? :devil:  :lol:   Clearly there is at least more of them/us!  Note I also have a 2005 crf450 actuall 488, but who's counting!

 

Got this bike with motor in 5-boxes!  Bike was disassembled by shop,  PO was quoted 4500 to fix.... must have nearly died!!, So the shop put the motor in a "doggy bag" for take home LOL.   Believe it or not nothing was missing. I had to rebuild lt from the crank up and during final stages of assembly I noticed the cam chain is loose as hell.  About 1cm of slack with adjuster fully extended!  Counted 124 pins (could it be the wrong chain--doubt it).  Backtracked to check chain guide installation, and that the chain was on crank sprocket (yes)! Chain Guides do not appear excessively worn.   Any Ideas? no way IMO, can a chain be that stretched?  so...are the guides bent out of shape (Don;t think So)?   Did I do something wrong, or did the shop give me the wrong chain???

 

Please look at these pics. and yeah I know, why did you not replace the chain!!!  Becuase its easy to get too later and I want to ride and sell soon, but I do want it to be a good bike for someone.  Buying a chain and guides as a method of checking the old chain for wear/fit is not an option I really want to excersise at this point.  Thanks for looking guys!

 

 

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Edited by bikedad1

You need a service manual, so you can check part numbers.

I wouldn't assemble anything till you do that.

Unfortunately the OEM parts listing doesn't show the pin count on the cam chain, so I'm not sure if that is the correct chain or not.  Both of the guides look good and I doubt it would give you that much stretch if it was.  That bike came stock with an auto cam chain tensioner so the issue might be that the tensioner is going bad and not holding the correct tension on the chain.  This is a very common problem with lots of bikes as the ratchet and spring assembly wear out and are unable to tension the chain enough.

I just found through Wiseco's website that the stock cam chain is 124 links and an "M" style chain, so it seems as though you have the correct cam chain in there.

Ya I counted links on pictures of stock chains and got 124 too, witch matches my count!.  The tensioner is working perfectly and fully extended and installed, in the photo with my hand showing the slack. On the tensioner, the  ratchet engages each notch solidly and the rod appears to be bottoming out when fully extended, (like it should) on a pin that appears to run through the shaft, when the spring pushes on it.   I do have a service manual and there is no reference to number of links checked against a measured length.  This is really weird.  This motor is staying exactly where it is until I can get this figured out.  I can't even safely rotate the engine as is by hand.  Thankyou so much guys, for responding!

 

So is it possible the chain stretched this much?  I find it really hard to believe and the only thing I can think of is its the wrong chain.  Remember motor was in boxes when I got it LOL.  Chain guides all line up and are installed correctly (pretty sure), its a simple operation.

 

BTW a new chain is on order!

Edited by bikedad1

I got a used 08 that had a very stretched cam chain. Bike looked great! But i almost knew the chain was loose from the sound the engine was making. Clink clink clink. Sure enough chain was freaking loose. New chain and problem solved. Dont know why chain stretched so much but it did.

So you think that much stretch is possible?  Strange thing is I can't even turn the engine over on the bench with that much stretch without it skipping a tooth!

 

I guess this is all kinda moot, since I am getting a new chain.  But I did  learn that Honda guys are way better at responding to posts that suzuki guys!  I'm both.  so not sure where that puts me!  Still it baffles me as to how badly the chain fits, and a piece of me is blaming my build skills, but for the life of me I can't see how I would or could have screwed up!

Mine was so loose that i could almost make it skip a tooth with my hand. I really got on the gas when i was testing it out. How it never jumped time is a mystery. It had an auto tensioner, and at first i thought it was broken....but it was just fully extended.

WOW!!  so looks like my condition (stretching) is possible!  Thankyou, I really needed to hear that, gives me some hope that on friday I will be bolting an engine to my frame!  I will keep you posted! 

Yes your chain has stretched that much, it can happen, and did.  If you keep it ditch the auto tensioner and get a manual one!

 

Or I just make my own from the stock one by tapping it and putting a big, longer bolt and locknut on it with an o-ring on the outside to stop leaking.

No,keeping the old chain...  new chain on the way!  Just the feedback I needed!

$4500...It's that kind of blatant robbery that gave modern 4-strokes their awful stigma of being super expensive to rebuild. I could rebuild the engine in my car 5 times over top to bottom for that kind of cash, or pay a shop to do it twice!

No Kidding!  In reality the head was a bit chewed (jounals) but were still usable for a season or two with new cams.  Engine may have injested sand (thats the story)  Crank pin a bit worn, but crank seemed ok, really for re-service (not racing).  Crank bearings still quite tight, Cylinder and piston were like gold,  perfectly in spec.  Butt.... my stupid purist sense made me redo Crank, bearings, piston, head and cams.  Worth it in the end depending on your pespective.  I'm selling the bike soon should make 500.00  just to have room (aka permission) to get a snow machine, winters on its way in the north!.  Still amazed at the stretch in the cam chain!

 

So that makes my time worth 10 bucks and hour, god I could open up a shop and undecut everyone.  Could have done that repair with new cams, wristpin,rings and a chain only for what 350  bucks!  oyeah got to add 4 more hours to get the bike running....nother 40 bucks there!

Edited by bikedad1

Yes your chain has stretched that much, it can happen, and did.  If you keep it ditch the auto tensioner and get a manual one!

 

All this great advice.  In your example above, wouldn't a manual CCT actually have more potential to cause damage with a slack cam chain since it has zero ability to automatically take up any slack?  Or, perhaps, you propose a conspiracy in which the ACCT actually stretched the cam chain in the first place!

All this great advice.  In your example above, wouldn't a manual CCT actually have more potential to cause damage with a slack cam chain since it has zero ability to automatically take up any slack?  Or, perhaps, you propose a conspiracy in which the ACCT actually stretched the cam chain in the first place!

 

Unlikely if you check it once in a while, the failure happens when the stock auto tensioner just completely lets go and allows the chain to jump a few teeth causing interference inside the engine.  

 

A manual one will never back out so its much safer IMO.  I have grenaded a motor due to one (stock) letting go, broke everything including cylinder, piston, head, cam, etc....manual ones for me from here on out.

Interesting.  I would imagine an inspection of the tensioner assembly then (Automatic one) should be added the the list if regular maintenance.  I would think that the one that gernaded your motor should have shown signs of failure or stress.  Even if so, still some good food for thought.  Now I'm gonna be paranoind...Thanks a lot Speed-FreeK!!!

Chain is stretched. All great advice above too. 

MCCT $50, failed one = blown engine your time -400 per hr LOl...

No kidding!  When I got to that stage last friday and discovered this, I saw my first ride that very weekend slip away.  Still waiting for new chain and praying that's all it is.  Again...that stretched.  How could the engine ever have worked? .

Have you looked for points of wear inside the motor ?

A severely loose chain would do some damage

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