2006 yz450f cam chain problem

My cam chain tensioner is all the way out, and my chain jumped time yesterday while pretty much idleing. I just put a new cam chain on from Yamaha. Was it to tight and I stretched it? Is the guide worn? Or was the cam chain I got off eBay not genuine even though it was packaged from Yamaha/genuine chain. It was tight when I put it together. Now it's loose. Also I tightened it super tight then backed maybe half turn off and left it. Not sure what to do. Seems a little loose to me to ride it especially because the tensioner is already all the way out.

1) It is not possible to install a brand new OEM timing chain without removing the cams because it's not long enough to allow it to be rolled over the cams while they are in place, and there isn't enough room to get the chain past the sides of the sprockets.


2) The tensioner is NOT supposed to be adjusted by the user; it is self adjusting.  Every one of them will advance to the fully extended position as soon as it is removed. 


3) To assemble the tensioner, the 10mm hex head screw is removed from the back end, and the tensioner drive screw is rotated clockwise until it stops.  This will retract the tensioner plunger completely.   The tensioner may hold itself in this position, or you may have to hold it yourself.  New ones come pre-compressed, with a small metal key holding them.  AFTER the tensioner is bolted to the cylinder, THEN the tensioner is released to find its own degree of tension.


Service manual:  http://www.yamaha-motor.eu/eu/services/owner-manuals/index.aspx

Exactly. You also have to take the flywheel off. So back to the question. Any thoughts

I have a manual. And I did just like it said. Once you twist the tensioner flat head screw it detract s and won't go back without screwing again clockwise. I did all that and it jumped time yesterday at about idle. Now my new chain is either stretched or?? Somethj g has caused my tensioner to detract fully. Its all the way out and the chain is semi loose

When I take a flashlight and look down at the tensioner installed I can clearly see it's all the way out, I checked by twisting the screw counterclockwise also and the chain isn't tight. I guess by me twisting it a little more then what it released itself I stretched it. Does that sound right? How much play should the chain have In between the cams?

No play after the engine has been rotated in a forward direction. 


Sounds like you might need a new chain, tensioner, and possibly a rear guide, as it sounds like you have bent something.

That's why I don't get it. I installed the new chain and tensioner and let it detract and the chain still had a very small up and down motion so I twisted the tensioner a hair more to make sure it was tight then rotated the motor and it was still tight so I put it back together. That was the first time. Now it jumped time yesterday in 1st going walking speed so I took it apart today and that's how it was. I thought maybe the guide to where it touches the tensioner was worn bad. Idk I just wanna get it right and not blow it up. It has a lot of play. The gears look fine so I guess the safe thing to so is what you said. Any other thing I should check? Can a get a manual tensioner?

Use a torque wrench on your cam caps? Seat the caps completely by hand before torquing? 

Yes, yes. Im checking everything now. No clue what so ever why it did this other than the chain I bought wasn't good. My teeth on the cams look a little worn, the chain sliding did that I'm sure. I'm lost as to why it's so loose. The guide seems ok worn but not bad. It must be a bad chain idk

Frankly, it sounds like you need to have someone with some experience have a look at it.

Ill get it. :) Thanks

Grayracer why would my clutch skip when letting off the lever in 1st slowly. Once it goes it's fine. And I ordered a cam chain off tt hopefully that'll solve my chain bring loose issue, any advice? Thanks again for you help I appreciate it

I took my new cam chain out of the bike just now and lined it up comparing my old one to it and they look the same length exactly. By eye. When I put the new one in a few weeks ago it was shorter and was easy to see it was. So I found the problem. The new chain is stretched. Ordered another one from tt. If anyone has anymore ideas y it stretched I'd be interested in knowing although I think I did it by over turning the tensioner screw, which Gray racer clear up for me that your not supposed to do that but the chain had what I thought was just a little to much up and down motion the first time so I turned it a hair more tighten ing the chain more.

Grayracer I ordered a new cam chain from tt oem and installed it, let the tensioner go and left it alone this time. So it wouldn't start and I checked the valves and 2 of the intakes were like .4mm

It bent the valves. Any pointers to do the valves? I can do it but I never have

No, actually, you can't do it.  Not unless you have a set of valve seat refinishing tools.  Take the head off, buy the valves, springs, seals and gaskets, then take the head and the parts to a small engine machine shop with experience doing valve jobs on YZF's. 

Can I skip the seat refinishing part? Do people do that?

Oem parts or aftermarket thank you again. Stainless or just order oem. And obviously do them all?

Can I skip the seat refinishing part? Do people do that?


Only if you want them to leak and wear out quickly.

Oem parts or aftermarket thank you again. Stainless or just order oem. And obviously do them all?


OEM.  No need to replace those that aren't bent and aren't showing significant wear.

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