Installing cam chain. How the heck...?


12 replies to this topic
  • Math

Posted April 03, 2005 - 04:52 PM

#1

Can someone tell me how I'm suppposed to get that friggin chain on the cams? :naughty:

First of: the chain slide on the exhaust side (front) is so stiff that I can't even put the exhaust cam in place and leave it there... it will pop out by the action of the chain slide that comes back straight by itself...

Is it normal that this chain slide almost reaches the surface of the head while the other one is much lower in the chain well?

Second, even if all of this is normal, I can't get the chain to go around the intake cam gear once the exhaust one is installed. :D I'm afraid to bend the chain... I've tried to lift the left side to create some slack but it ain't enough... God! I'm asking myself how I succeeded to remove those cams :naughty:

I probably need another pair of hands...

Any tricks?

Thanks

  • clark4131

Posted April 03, 2005 - 07:28 PM

#2

Stupid question, but you did remove the tensioner right? When I did my valves at 100 miles, my chain was tight as well, but not as much as you're describing. I found that I had to remove the intake cam first by rotating it towards the exhaust cam. Once it came out, then there was no problem. To reinstall, I reversed the process. It was not exactly easy, especially getting everything to line up at TDC, but it only took me three tries and I got it. After you bolt the cams back down, that's when you replace the tensioner. You may already know this, but I figured it was worth a shot. Other than that, is your chain properly mounted down in the case?...SC

  • scott_h

Posted April 03, 2005 - 10:42 PM

#3

Math,

It doesn't sound like the forward (exhaust side) cam chain slider is not properly installed. It should be well below the exhaust cam chain sprocket and there should be no interference between the two at all. There is a notch in the cylinder that the cam chain will fit into. You can see it here right underneath were the cam chain is resting in this picture:

Posted Image

There are two tabs sticking out of the slide about the mid point and these tabs fit into the notch in the cylinder. If I remember right, there is also a small cup cast into the case near the crankshaft that the lower end of the slider fits into.

Another possibility is the chain is balled up a little around the crankshaft sprocket. To make sure everything is in order you can pull the flywheel and stator plate to get a good view of the cam chain, crankshaft drive sprocket and lower sections of the chain sliders. Once you are satisfied that everything is order reinstall the stator and flywheel since you will need to make sure it is at TDC while installing the cam chain and setting the cam timing.

No matter what (even with the cam chain tensioner removed, you will not be able to install the chain on the cam sprockets while both cams are installed in the head. My technique is have one cam resting in the head normally (no need to have the cam cap installed) with the chain on this cam sprocket and all the slack taken out of the chain between this cam and crank. That will give you the maximum amount of slack when installing the other cam. Next position the other cam sprocket further towards the right and leaned into the cam chain well and moved toward the cam that is already installed. The idea is to shorten up the gap between the two sprockets. To do this the cam bearing will sitting in the chain well and you'll have to tip the right-hand side of the cam up some. In this position, the sprockets won’t be lined up at all, but you should have enough slack in the chain to slip over the cam sprocket that you’re holding cockeyed. I find it a little easier maneuvering the intake cam around and leaving the exhaust cam in place in the head, but it can be accomplished using ether cam.

Once you've got the chain on the sprocket, place the cam into in the head. To do this you'll have to rotate the cam a little bit to move it back. Once you've got both cams in, position the exhaust cam timing where it should be. Make sure you’ve got all the slack out of the chain between the crank and exhaust cam. This will put all the free slack on the intake side. You should now have enough slack in the cam chain to barley lift it off the sprocket so you can rotate and adjust the intake cam timing as necessary. You will only be able to do this one tooth at a time. Take your time. Make sure the crank stays at TDC and pay attention to the cam sprocket marks.

Posted Image


When you think you’ve got timed right, I recommend installing the cam caps and chain tensioner and rotate the crank and few full turns to check for any abnormal binding and then recheck the valve timing and lash just incase something was out of whack when it was put together.

Scott

  • shawnwt

Posted April 04, 2005 - 05:11 AM

#4

hey Scott

NICE PICS :naughty:

  • Math

Posted April 04, 2005 - 05:39 AM

#5

Thanks guys!

To eliminate all doubts, yes the chain tensioner is removed.

Seems to me that the problem is the chain guide. This has been the problem since I started to rebuilt the engine... could not remember where it should go. A TT fellow tried to explain this notch thing to me and did it good but I got him wrong :D Thanks for the pic of the notch! :naughty: :D :naughty: :D

Now it looks like I'm gonna have to remove the head again to put this friggin slider in place. :cry:

If the head has been torqued to specs, do you think the gasket located right under is busted?

Thanks for all informations... :D

  • Crashly

Posted April 04, 2005 - 08:51 AM

#6

Thanks for the help guys. I am right in the middle of reassembly right now and I have this same exact problem. Looks like I did not properly install the exhaust side chain slide tensioner correctly :D . Off with its head :naughty: :naughty: I think the gasket should be able to be reused, since it has not received any heat yet.

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  • Frostbite

Posted April 04, 2005 - 09:25 AM

#7

Like Scott said, the cam chain could have slipped a link on the crank sprocket, happened to me. The chain is tight and you have to play around to get the cams in, but if it seems insanely tight, you probably jumped a link. It's always a good idea to install new gaskets, but if the engine hasn't been run I'll reuse head gaskets.

  • Math

Posted April 04, 2005 - 09:42 AM

#8

I see it's your second post Crashly so welcome aboard!

Hi Frostbite, haven't talk to you in a while... how are things going in your part of the country?

Thanks to you two for your input. I'll have a look at it during the week and will let you know. I'll probably re-use the gasket making sure it is dot dammage (I have another new one home). I would not like to have to use another since they retail at about 40$ here at the dealer :naughty:

I hope I'll be able to put this thing back to its place!

Later,

  • Sylvain

Posted April 04, 2005 - 10:40 AM

#9

Hello Math

Seems like there is a lot of people working on their cylinder head. Good timing for all this welcomed infos. :naughty: .

Regarding the head gasket, the part guy at the yamaha dealer told me to use a new one once it has been torqued. We could always reuse it but the chance to develop a leak is Much more possible.

I had to take off the head and the barrel, as well as the ignition side to have a look inside the bottom of cam chain cavity. Guess what ? I lost the f****g half moon clip of the bearing cam cap :naughty: . I searched all over the basement with no result. So I had to dig deeper in the engine to make sure the clip wasn't there. I took all kind of measurements, everything looked OK. I ordered a new clip (4.95) it should come in at the end of the week.

By the way I was wondering where you got your parts and how much you paid for the set of rings. I tough about replacing the rings while the engine is open.

Question for you guys.

If I replace the rings should the cylinder be honed ?

There seems to have some type lub on the long cylinder head bolts, what is it ? Anti-seize?

Also right in the middle of the cylinder head there is an allen head bolt that doesn't seem to do much, any info on it ?

Thanks to all

  • Math

Posted April 04, 2005 - 10:48 AM

#10

I had two complete sets of rings, and gaskets coming with the bike when I bought it used. Don't know where it comes from but I guess that when my seller actually purchased the bike new, he asked for it. I don't know if it is a routine practice at Alary (maybe Sleeman could tell us...) to provide this with the bike ...

You don't necessarily need to hone the cylinder according to my cousin who's a mechanic. I did not since it was in very good shape according to his eyes.

  • Sylvain

Posted April 04, 2005 - 10:43 PM

#11

Thanks for the infos

  • yz250frzing

Posted January 23, 2006 - 06:01 PM

#12

hey iv got the same problem with the exhust cam rubbing on the guide how did u fix that thanks james

  • ncampion

Posted January 23, 2006 - 06:18 PM

#13

Here's a neat and cheap tool for all you guys setting cam timing. It keeps the crank from turning while you're fooling around with the cams. It's just a 14mm bolt with the end ground to a blunt point. Hand tight only!

http://i32.photobuck...um/DSCN3680.jpg




 
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