GS450 cam/valve issue

[greg]

I searched, but didn't find the answer I was looking for. I got a gs450 a few weeks ago, and the cylinder head had all broken off studs, so I took the head off to take to a shop to get it taken care of. That went fine. Tonight I was putting the head back on, and for the life of me I can't get the exhaust cam #1 Arrow to line up with the gasket without the left side of the cam coming out of the journal due to the cam lobe hitting the valve. I thought maybe the shim bucket wasn't seated, but that doesn't look like the case. I'm stumped, and I'm guessing I'm over thinking something. Any suggestions?

Thanks,
Greg

 

[Nessism]

Did you position the crank at 1 TDC?

Did you use vice grips to clamp down the cam into the bearing saddles before installing and tightening the cam caps?

 

[greg]

I have the crank for the right piston at TDC. My Clymer manual didn't say anything about clamping the cam with a vice grip, I'll give that a shot. Thanks!

 

[greg]

Using some vice grips I got the #1 arrow to finally get where it needs to be, but after I tightened up the caps and took the vice grips off, the cam just went right back to where I started. Is this normal?

 

[Guest]

The trick to doing this is to get it set so that you have the right number of links between the #2 and #3 and then while holding the chain on the cam's rotate the crank backwards about 1/4 turn, That lets the cam's fall into a sweet spot while keeping everything in time and where the lobes are not pushing down.
Tighten down the cam cap's in that position and let the tensioner out to take up the slack.

Then try turning the crank forward to TDC and check the marks again.
While turning the crank you should see the cam's moving right away. If not, you could have some slack in the front of the cam chain between the exhaust cam and the crank.
Try and make sure you have no slack in the front and push all the slack to the back part.

There is a sweet spot where you can get the exhaust cam to lay in place with almost no pressure pushing it in any direction.

Once you let the tensioner out and rotate the crank back up to TDC you might be perfectly aligned or at least you can see if your 1-2 teeth off forward or backwards.

if you are off:
All you have to do is rotate it back to the sweet spot, loosen the tensioner and then take the cam caps off.
Pull the cam up a bit and jump the chain a few teeth in the right direction and then put it back together and check it again when you turn the crank forward.

do this a few times until you get the exhaust cam right on.

Don't worry about the intake cam yet, Your probably almost right on.

After you do get the exhaust cam to rotate with the crank and line up perfectly with TDC and the #1 facing forward you can count the number of pins between the #2 and #3. Then just rotate it backwards again to the sweet spot and take the intake cam out so you can set the right number of links.

Re-assemble and you should be right on.

 

[bwanna]

After you think you have it ALWAYS hand rotate the engine a number of times to make sure the valves aren't hitting. Go slow as each of the valves are being pushed down. If that's successful, then hand rotate through a number of complete rotations to be sure. At least this way, if you are off you won't bend any of the valves.