camshaft chain replacement,pulling the trigger

[tom n]

Hello all, thanks for your previous posts, you never know who your gonna help. I have a 2007 yz450f with 59.8 hrs on her with NOTHING wrong. I've never checked the valves and never replaced the timing chain so i'm gonna go ahead and give them a shot.

When replacing the camshaft chain, I'm gonna keep the stock camshafts but what i'm not sure about is do I need to replace the front and rear camshaft chain guides? I was just going to buy a new chain and tensioner (from t/t!).Is it also nessesary to buy any other seals,gaskets,bolts?

The tools I have are flywheel puller,torx,1/4" torque wrench,feeler guages and any other sockets I should need. I have all the other basic tools but are there any others i'm forgetting?

I believe I have a good idea of how to do this from the sticky's and the service manual, are there any other warnings or tricks that come to mind? Thanks in advance, I'm gonna give it a try, i'll be posting with any issues i face:thumbsup:

[Gunner354]

Hello all, thanks for your previous posts, you never know who your gonna help. I have a 2007 yz450f with 59.8 hrs on her with NOTHING wrong. I've never checked the valves and never replaced the timing chain so i'm gonna go ahead and give them a shot.

When replacing the camshaft chain, I'm gonna keep the stock camshafts but what i'm not sure about is do I need to replace the front and rear camshaft chain guides? I was just going to buy a new chain and tensioner (from t/t!).Is it also nessesary to buy any other seals,gaskets,bolts?

The tools I have are flywheel puller,torx,1/4" torque wrench,feeler guages and any other sockets I should need. I have all the other basic tools but are there any others i'm forgetting?

I believe I have a good idea of how to do this from the sticky's and the service manual, are there any other warnings or tricks that come to mind? Thanks in advance, I'm gonna give it a try, i'll be posting with any issues i face:thumbsup:

I would pull the valve cover and check for any kinks. If not just save your money.

I have an 09 with just under 400 hrs on the original chain.

[KJ790]

Definitely replace the chain. It's cheap and easy to do. I was shocked when I changed my cam chain at 50 hours and held it up next to the new chain. The used chain was significantly longer, even though it didn't kink yet, it was significantly worn. Running a chain that is stretched that much will damage the sprocket on the crank shaft, which requires you to buy a new crankshaft and split the cases to fix... much easier to buy a $25 cam chain and spend 20 minutes changing it once in a while.

As for your questions, you shouldn't have to replace any of the guides with that little bit of time on it. You shouldn't need to replace the tensioner either unless it is malfunctioning, but some people feel better by replacing it anyways. There is a gasket between the head and the tensioner, I have have reused the same gasket in the past with success, but you may want to pick up one of those to be safe since they are really cheap. You will also need to get a new ignition cover gasket. Make sure when you put it back together that the cam timing is correct with tension on the chain, this is one of the most common mistakes. If the timing looks right without tension on the chain, odds are the timing is off by one tooth on the intake side.

Edited March 2, 2011 by KJ790

[tom n]

I think i'm gonna go ahead and change it anyway. I do understand that the chain not under tension gives a different "reading" than when it is under tension. I'll be careful to watch out for that the best I can. Your last two words on the previous reply kinda concern me, i'm not sure I understand the "ignition side", did you maybe mean "intake"? Sorry, just a little confused. I'll be sure to get the new gaskets we spoke of also. thanks again

[crf450319]

I replaced my cam chain at 60.9 hours and I had 6 or 7 links that were binding, I run Amsoil MCF and change it at 7 hour intervals. For the cost of a new chain, I think it's well worth replacing.

When you are re-assembling and putting the cam caps back on MAKE SURE you can have the caps seat completely flush on the head by hand. What I'm saying is, you should be able to press the cam cap onto the head with a little pressure from your hand. If you can't your cam may not be aligned properly from left to right.

I went through that, and had a pretty close call - you can't replace just the cam caps, the whole head/caps have to be replaced as one unit. My exhaust cam was 1/32" too far to the left and damaged my cam cap (where the clip fits into the recessed area on the cap). Make sure your cams are properly lined up from left to right, if you can't have the cam cap seat by hand, they're more than likely not lined up correctly.

This isn't a big deal, but something that you've got to pay attention to. I'd had my Honda's apart 5 or 6 times and never ran into this, they always seemed to "fall" into place.

[KJ790]

I think i'm gonna go ahead and change it anyway. I do understand that the chain not under tension gives a different "reading" than when it is under tension. I'll be careful to watch out for that the best I can. Your last two words on the previous reply kinda concern me, i'm not sure I understand the "ignition side", did you maybe mean "intake"? Sorry, just a little confused. I'll be sure to get the new gaskets we spoke of also. thanks again

Oops, my bad... that's what happens when I don't read over what I write ? It was supposed to say intake side, I fixed it.

[tom n]

thanks crf450319, I think I know what your talking about and thanks for the heads up. But I was under the impression that the cams "slip" into pockets on the head that are mated to accept the cams to seat them properly, No? Then the cam caps are stepped(?) to only go on one way or not at all. Right? This leads me to think that theres no way the caps can seat improperly unless you are way off. Then again, i'm the guy to screw something like that up and be online here begging you folks for help.I think that your right though, its not that the cam is rotated incorrectly,but instead the cam is canted or skewed (no longer perpendicular) and is therefor not seated correctly. Right?...

[nokickstandsallowed]

I have an 09 with just under 400 hrs on the original chain.

Just under 400 hours? I'm appalled. I just trashed a brand new top end with a brand new cam chain that had 1.2 hours on it. It wasn't the cause of my failure; but the collateral secondary damage caused the cam chain to have about 3 very, very, very tight links. I have had a far worse catastrophe of the top end being trashed (partial piston shatter) and the new cam chain was undamaged (no tight links or kinks) but replaced anyway. I'm just gonna go sit in the basement and really start contemplating about throwing a match in my gas tank. Mines a 250F; but, it is recommended to change the cam chain yearly. It is possible to get 400 hours a year ride time easily and I replaced the cam chain every 200 hours (I did it three years straight); however, that is not the case for me this year in light of the fact I blew a brand new top end and it isn't even April. Replace that cam chain soon partner.

Ride On!

Edited March 2, 2011 by nokickstandsallowed
For lack of better knowledge - I have no idea!

[crf450319]

thanks crf450319, I think I know what your talking about and thanks for the heads up. But I was under the impression that the cams "slip" into pockets on the head that are mated to accept the cams to seat them properly, No? Then the cam caps are stepped(?) to only go on one way or not at all. Right? This leads me to think that theres no way the caps can seat improperly unless you are way off. Then again, i'm the guy to screw something like that up and be online here begging you folks for help.I think that your right though, its not that the cam is rotated incorrectly,but instead the cam is canted or skewed (no longer perpendicular) and is therefor not seated correctly. Right?...

You are right, the caps can't be off from left to right, the bolts simply wouldn't go into the holes. But, the cam itself can be off center.

The cams do "slip" into the pockets on the head, but they can be off by 1/32" to the left - causing the damage pictured. Like I'd said, the cams in my Honda never required any attention to be centered from left to right, or maybe they did and I just got lucky the 5 or 6 times I had it apart ?

The bearing on each cam has a recess in it, as do both of the cam caps. The recess is there for a circlip, that circlip is what ensures that the cam is centered from left to right. This isn't a big deal, but something to be aware of - it's a little difficult to see if your cam is 1/32" off to the left if you're not looking for it, or not thinking/realizing that it could be off. If you can't get the cam cap to seat properly on to the head by hand, something isn't lined up correctly.

Edited March 2, 2011 by crf450319
Added line about cam caps not being able to be off center.

[grayracer513]

The above post is an example of why I always advise that the cam caps MUST be seated completely by hand, and never pulled down into place by tightening the bolts. Besides the fact that the cams can drift left/right out of place as demonstrated above, the dowel pins may also misalign because of the cam moving over. Always try to completely seat the cam caps down on the head just by pushing them into place with your fingers, then tighten them to torque in three steps using the pattern shown it the manual.

[Gunner354]

Just under 400 hours? I'm appalled. I just trashed a brand new top end with a brand new cam chain that had 1.2 hours on it. It wasn't the cause of my failure; but the collateral secondary damage caused the cam chain to have about 3 very, very, very tight links. I have had a far worse catastrophe of the top end being trashed (partial piston shatter) and the new cam chain was undamaged (no tight links or kinks) but replaced anyway. I'm just gonna go sit in the basement and really start contemplating about throwing a match in my gas tank. Mines a 250F; but, it is recommended to change the cam chain yearly. It is possible to get 400 hours a year ride time easily and I replaced the cam chain every 200 hours (I did it three years straight); however, that is not the case for me this year in light of the fact I blew a brand new top end and it isn't even April. Replace that cam chain soon partner.

Ride On!

I still stand by my exceptional cam chain life and top end life to the use of a polyol ester oil. Specifically Redline oil. I also had the same longevity on my 01 250f. Pay a little more now or pay a lot later.

It's just amazing that people do not use a top of the line oil in these motors that turn 11,000 rpm's and wonder why they have issues. No offense people, but wake up.

[tom n]

Thats a huge help and there is no way I would have known to look for that!! As I stated before i'm sure I would be the guy to screw that up! So thanks for the tip. I understand what to watch out for. Lastly, (since i'm waiting for the parts to come in) Is it possible/advised to count the number of links FROM a point on the CRANKSHAFT gear to another point on the intake CAMSHAFT gear? I was thinking of whiting out a point on each and then counting it out.... or am I just thinking into it to much? (this differs from greyracers how-to where he writes of camshaft to camshaft relationship but not a camshaft to crankshaft relationship) PS I plan on documenting this very well (pics and video) and possibly posting onto this site if all goes well, that way it should answer a whole lot of future questions! Thanks

[brentn]

I'm glad I found this thread, lots of useful information here.

[Mr. Neutron]

Tom N.,

When I replaced my cam chain at 60 hours, a couple of weeks ago, I never bothered to count pins. Once I had the valve cover off, and could look things over real well, see the timing marks on the cams, & etc., it didn't seem to me like it was necessary to count pins. With the timing mark on the crank aligned, and with the cams' marks lined up as it show in the manual, you'll know that you're good to go. ? For me, one minor "problem" was distinguishing the correct mark on the flywheel. As the flywheel rotates ccw, that one "H" shaped mark had me almost fooled. The middle bar in the "H" is kinda long, and I first thought the rt. end of that "H" was the TDC mark. I figured it out, eventually.....?

I really wish someone could tell me an easy way to "move" the cam chain on the cam sprockets to get things aligned as they should be. I never could figure out a good "system" for doing that. I would invariably set the cams up with one cam or the other off by a tooth or two, and then have to get the chain off, rotate the cam(s) slightly, and try again. That's definitely a finesse type of deal there...... ?

Jimmie

Edited March 3, 2011 by Diesel Goober
'cause it needed it....

[grayracer513]

T Is it possible/advised to count the number of links FROM a point on the CRANKSHAFT gear to another point on the intake CAMSHAFT gear? I was thinking of whiting out a point on each and then counting it out.... or am I just thinking into it to much? (this differs from greyracers how-to where he writes of camshaft to camshaft relationship but not a camshaft to crankshaft relationship)

It's not practical or necessary to count links form the crank. Impractical because the chain isn't visible, and unnecessary because the exhaust cam timing mark is simple to accurately place and to move if you get it wrong.

I really wish someone could tell me an easy way to "move" the cam chain on the cam sprockets to get things aligned as they should be. I never could figure out a good "system" for doing that.

What I do is this: Set the exhaust cam first, drawing the slack out of the front of the chain to be sure both the crank and the exhaust cam are in the right spot using the marks. Then, from the 12:00 o'clock mark on the exhaust cam, count 14 pins and put the 12:00 o'clock mark on the intake between the 14th and 15th pin. Keeping the chain in this relationship, roll the intake into place. Then, rotate the crank and both cams back just a couple of degrees and turn the crank slowly forward to TDC.

Check the timing marks on both cams. (don't rely on counting pins, rely on the marks) They will almost never be perfect, but if you think it is off, visualize the mark at the next tooth (or mark it with a Sharpie) and see what that would look like. Better? Change it. Not better? Leave it. Torque the caps, install the tensioner, then rotate the engine back 10 degrees and forward again to TDC to double check.

[Mr. Neutron]

It's not practical or necessary to count links form the crank. Impractical because the chain isn't visible, and unnecessary because the exhaust cam timing mark is simple to accurately place and to move if you get it wrong.

What I do is this: Set the exhaust cam first, drawing the slack out of the front of the chain to be sure both the crank and the exhaust cam are in the right spot using the marks. Then, from the 12:00 o'clock mark on the exhaust cam, count 14 pins and put the 12:00 o'clock mark on the intake between the 14th and 15th pin. Keeping the chain in this relationship, roll the intake into place. Then, rotate the crank and both cams back just a couple of degrees and turn the crank slowly forward to TDC.

Check the timing marks on both cams. (don't rely on counting pins, rely on the marks) They will almost never be perfect, but if you think it is off, visualize the mark at the next tooth (or mark it with a Sharpie) and see what that would look like. Better? Change it. Not better? Leave it. Torque the caps, install the tensioner, then rotate the engine back 10 degrees and forward again to TDC to double check.

? That helps, and a lot!!! Thanks, Grayracer513!!! I agree with BrentN; this is a really helpful thread! ?

Jimmie

[tom n]

Parts come in Friday or Saturday! I'll be riding the 2 stroke Saturday so Sunday should be the day i'm doing the chain. So if you guys aren't doing anything after Church, If I run into trouble, I'll be the post that says "HELP!, TIMING CHAIN ISSUE!".? But seriously, thanks to all !!! PS, i'll post again when the 450 starts.

[Mr. Neutron]

Good luck, Tom!! ?

Really, between a good Yamaha manual, this forum, & in particular this thread, it should go pretty well for ya. Man, I'm glad for the this resource here. The folks in this forum, and this website, are great!

Jimmie

[tom n]

Hello all, I completed the valve check/camshaft chain replacement!!! I learned alot:ride:, and took as much advise into consideration as I could. Ya know what? It was great!! From greyracer to Jimmie to all others made for a great thread, sorry if I didn't mention you, I just dont know everyones name. Took lots of pics!!!! I'll post some during the week. I went the "mark the chain and shafts together, then transfer your marks from one chain to another" route as my pics will show. This relieved any confusion because I can count to 50!? Seriously, thats the way to go! Oohh, the chain I had was.... fine. Maybe very slightly stretched. But I would change it again in another 50 hrs in a second! Lastly, when checking the valves, both the intake and exaust were UNDERVALUED? Meaning, the minimal gap listed in the manual was higher than my readings, triple checked. For instance, the manual says maybe .003 to .005 (just an example boys) and I would get .0015 or .002? Is this normal? I just moved along and dismissed it for now. Thanks to all again and i'll be posting over the work week. Thanks again, Tom

[KJ790]

Hello all, I completed the valve check/camshaft chain replacement!!! I learned alot:ride:, and took as much advise into consideration as I could. Ya know what? It was great!! From greyracer to Jimmie to all others made for a great thread, sorry if I didn't mention you, I just dont know everyones name. Took lots of pics!!!! I'll post some during the week. I went the "mark the chain and shafts together, then transfer your marks from one chain to another" route as my pics will show. This relieved any confusion because I can count to 50!? Seriously, thats the way to go! Oohh, the chain I had was.... fine. Maybe very slightly stretched. But I would change it again in another 50 hrs in a second! Lastly, when checking the valves, both the intake and exaust were UNDERVALUED? Meaning, the minimal gap listed in the manual was higher than my readings, triple checked. For instance, the manual says maybe .003 to .005 (just an example boys) and I would get .0015 or .002? Is this normal? I just moved along and dismissed it for now. Thanks to all again and i'll be posting over the work week. Thanks again, Tom

If your valves were too tight then they are starting to wear. You need to reshim to get them back into spec. Valves tighten as they wear, this is why you need to check the clearance and make sure that it is large enough (within spec). Get the valve clearance back into spec and then make sure you check them again pretty soon because if they are starting to wear then they will probably be out of spec again in less than 15 hours of riding. When they tighten up again it is safest to replace the valves and get the seats cut.