Please help! 1981 GS450L cam caps binding

[Guest]

Hey Guys,

I am in the process of finishing up my almost 2 year long project of rebuilding of my GS450 and have hit a brick wall! I completely tore down EVERYTHING and painted the motor and I’m stuck on trying to torque down the camshaft caps. This bike uses highly polished cam surfaces and ride in aluminum guides (no ball bearings) and they’re all in their correct orientations (A,B,C,D) but when I try to torque them down, they start to bind up and then can not rotate the camshafts freely anymore. I’ve tried to tighten the bolts evenly and I’ve tried one at a time (2 bolts per cap / 4 caps total) but nothing seems to want to work. When I do one side at a time, some caps get completely tightened down (both bolts), but then other caps still bind no matter what order I tighten them down in. I’ve heard that there are specific torque sequences, but with only 4 bolts per camshaft, the options are limited. I’ve even tried to tighten everything down without the shims on the valves (incase something was pushing weird on the camshafts preventing them from rotating) and still binds. All these problems are happening with both the intake and the exhaust camshafts. You don’t think that I warped the head at all by baking it in my oven at 350° for 20 mins. to cure the engine enamel do you? I did that to the cases and everything else went back together perfectly.

Have you ever heard of this problem or know what might be going on here? I can’t find anything online and anybody else I talk to about this just says “I’ve never heard of that”…UGH! I have a Clymer manual and of coarse, they don’t go into any detail on the caps…they just say to put them on…just like that huh?!?!

[tom203]

Go here and download factory service manual - it's 80mb. You gotta be missing something obvious in reinstalling.

https://skydrive.live.com/redir?resid=2370B62DDF9F0C6B%211334&authkey=%21APM7hx6Q2ynLu-A

edit: if no go,then go here and peruse other manuals

http://members.dslextreme.com/users/bikecliff/

[tom203]

Where are all the 450 guys to respond to this? Anyways, are you absolutely sure your cam bearing caps are in right spots with triangle mark(?) pointing forward ?

[osterizer03]

Yeah they make it pretty dummy proof. I like that design!

[tom203]

Hang in there, a 450 guy is bound to show up with input!

[terrylee]

Just a thought, but I believe there are small dowels that fit into holes in caps, maybe some fell out or are missing? Might allow caps to be over tightened? Each cap should be tightened in a crisscross pattern. terrylee

[Big Rich]

I'm with Terry - check for those locating pins. Is there any way the maybe the cams are flipped left & right, or maybe front & back? I would hope not, but if they are slightly different diameters in the wrong spots, the caps would bind up then too.

[GregT]

The twin heads are as simple as it gets - if the caps are in the correct locations - A front left, D rear right - and the dowels are in, shouldn't be a problem.
Even if you've got the cams wrong left to right they should still turn.
When you painted the head, you did mask off the interior ?

[osterizer03]

Yeah I did all of the appropriate taping and everything is in the correct orientation.

[osterizer03]

I forgot to say that i had also cleaned up the locating pins on the caps because they were a little dirty / starting to rust on my shelf....and still binds. I'm getting to the point where I'm about to make a shim that goes under the caps but I shouldn't have to do that. Plus who knows what else would wear out on the motor if I made a shim. The shim would have to be super thin....probably less than .001" thick.

[earlfor]

I think putting an aluminum head in a 350 deg oven for 20 minutes was probably the worst idea you ever had. I would take the head to a machine shop and have it checked for warps before I did anything else.

[posplayr]

I think putting an aluminum head in a 350 deg oven for 20 minutes was probably the worst idea you ever had. I would take the head to a machine shop and have it checked for warps before I did anything else.

You apparently did not see the OP's idea about shimming the cam caps LOL.

[osterizer03]

Yeah i realize that shimming the caps isn't a good idea. I'm surprised if the oven is what did it. Don't you think motor gets that hot while running? I used por-15 which cures when the motor heats up for the first time or When it is baked. I was worried that if I waited until the motor ran to cure the paint, I would only be left with half the paint after any tools touched the enamel or I got any oil on the enamel.

[posplayr]

Do you have a straight edge to check the bottom of the head or is it already torqued? Does the cam sit flat in the saddles or does it rock! Put each cap on finger tight , that cam better still spin. It can do be that you have galled the caps or saddles and the cam will not spin. I had this where there was some damage and it prevented the cam from spinning till I cut out the raised portions of the damage.

[GSX1000E]

Yes, the cylinder head gets to over 300 degrees normally. You might need to do as Posplayr suggested to the journals.