binding

[i57chevy]

I have an 81 gs750. I swapped the heads and everytime I tighten down on the cam bearing cams it binds up. If I loosen them it turns. I used the bearing caps and cam shafts from the head that was put on the lower unit. one motor, the one the head came off, was running but spun a rod bearing. The other one, the one that the head was replaced blew a spark plug. One motor was an L and the other a T. both has engine code gs75x. The cam cover holes don't line up though

[flyingace]

There was recently a post about something like this, but the news wasn't good. I think the cam bearings and caps are individualized for each head and can't be swapped out. This is backed up by the fact that you can't buy bearing caps as separate units.

Please don't take my word. I would research the posts and try to find the user who said this and PM them.

[earlfor]

You are correct.

Earl

There was recently a post about something like this, but the news wasn't good. I think the cam bearings and caps are individualized for each head and can't be swapped out. This is backed up by the fact that you can't buy bearing caps as separate units.

Please don't take my word. I would research the posts and try to find the user who said this and PM them.

[i57chevy]

but I used the bearing caps and camshafts from the head that I put on

[earlfor]

OH!!! I thought you were saying you mixed head, camshaft and caps.

Are you using the correct torque values and torque suquence?
What ft lbs and pattern? Did you oil the lobes first?

What do you mean the cam cover holes dont line up? You mean valve cover?

Earl

but I used the bearing caps and camshafts from the head that I put on

[hungryman]

Make sure the bearing caps are in their original positions. They are machined as a unit and cannot be randomly placed.

[earlfor]

Bingo!!! I just betcha! :-)

Earl

Make sure the bearing caps are in their original positions. They are machined as a unit and cannot be randomly placed.

[i57chevy]

I put them in the correct position as far as A B C D. I never really got as far as getting them torqued. any bit of tightness and it binds. and yes the valve cover. I just used the one for that head, but it seems odd being the same engine no. I started with the inside caps then the outer

[flyingace]

but I used the bearing caps and camshafts from the head that I put on

Sorry, it was a little confusing exactly what you did. And yes, they need to in the original positions.

[earlfor]

If I remember correctly, there is a stamped arrow on the top of the caps which should be pointing forward. When I assembled my 1150 top end, valve spring tension keeps everything from sitting in place seated. The camshafts are not going to be in proper alignment vertically until seated with the correct torque.
I'm inclined to think you're interpreting spring compression as binding. You should not be rotating the engine during the torque sequence on the cam caps, so I dont understand how you can say the cams bind and will not turn. Are you turning the bolts down in the criss cross, inside to outside pattern and in gradual steps of a couple of lbs at a time?

Earl

I put them in the correct position as far as A B C D. I never really got as far as getting them torqued. any bit of tightness and it binds. and yes the valve cover. I just used the one for that head, but it seems odd being the same engine no. I started with the inside caps then the outer

[i57chevy]

originally, I put the exhaust cam in position with the crank in the 1/4 position put the inside two caps on and snugged them. then the outside and snugged them then tightened in same sequence. Then I put the intake the same way. when I tried to turn the nut on the crank full circle I get a very very tight cam chain and no movement

[flyingace]

Well, if the bearings, caps, camshaft and head were all together originally, I can only think of two explanations:

1. they never fit to begin with.
2. you mixed them up somehow and didn't realize it.

Have you considered going back to the original head and heli-coiling the spark plug hole?

[earlfor]

To install the camshafts, the automatic cam chain tensioner must be removed. It is not reinstalled until camshaft installation is complete and torqued down. The engine should not be rotated until after the automatic tensioner has been reinstalled and set.

The proceedure by the factory manual is to align the crank to TDC. Do not move the crank position again. Lay the exhaust cam in place with the shaft end notches aligned to the cylinder head edge. 1^ on the exhaust cam sprocket will align with the head (pointing horizontal and forward). 2^ on the exhaust sprocket will be pointing straight up. Pull the camchain at the front of the engine up as tightly as you can (WITHOUT) moving the crankshaft and lay the chain over the sprocket. Slide into place and "roll" the intake cam into position with the camshaft end marks properly aligned to the cylinder head and the 3^ on the sprocket pointing straight up. The correct pin count between the sprockets is counted with the 1st pin directly over the 2^ and the last pin directly over the 3^. Most models have a 20 pin spacing, but you will have to check for your model. Now sequentially torque down the cam caps starting with the center on both camshafts in a criss cross pattern and working to the outers in a criss cross. Both camshafts are tightened in small increments and brought to torque simultaneously. Once they are to the correct torque, install the automatic cam chain tensioner. Then, with the spark plugs removed, and a 19mm wrench on the end of the crankshaft, slowly and lightly rotate the crank. If you feel anything solid or click, STOP.
The crank should rotate easily.

Put a squirt of oil on the the camshafts where the caps are to go before putting them in place.

Earl

originally, I put the exhaust cam in position with the crank in the 1/4 position put the inside two caps on and snugged them. then the outside and snugged them then tightened in same sequence. Then I put the intake the same way. when I tried to turn the nut on the crank full circle I get a very very tight cam chain and no movement

[i57chevy]

I did somehow mix them up and with many hours of intense studying seem to have got them matched. another contribution was the front chain guide. don't know if they are slightly different or damaged, but bike is running. with issues, though. hopefully minor. I do have an timing advance question. when the crank is at t for 1and4, cam end notches are pointing in, the 2 is up for exhaust, 3 up for intake, and chain 20 links apart is the notch on the govenor supposed to be lined up with the contact for 1 and 4 on the signal generator? hope that made sense.

[earlfor]

Until now, we have been talking about valve timing. Do I understand correctly that we are now referring to ignition timing? The crankshaft trigger sensor and receptor should be lined up for the #1 cylinder when the timing mark on the engine case is aligned with the |F1 on the side of the advance counterweight. That is the ignition mark for the 1 and 4 side.
The trigger aligns again on the |F2 for the 2 and 3 cylinders.
The marks visable on the side of the advance counterweight are:
|T |F1 |F4 on one counterweight and on the other counterweight you will see: |F2 |F3. The marks (|) for F4 and F3 are full advance marks for the 1,4 and 2,3 cylinders respectively. |T is TDC and used for valve timing.

To set ignition timing, rotate the crankshaft until the marks on the case and the breaker plate are in align for the 1,4 side, that would be |F1. Then rotate the breaker plate until the crank trigger/sensor is in the correct position. For the 2,3 trigger, you have to move the trigger assembly since you cannot again move the whole breaker plate.

Or maybe I have missed understanding your question completely. If so, try again. LOL

Earl

I did somehow mix them up and with many hours of intense studying seem to have got them matched. another contribution was the front chain guide. don't know if they are slightly different or damaged, but bike is running. with issues, though. hopefully minor. I do have an timing advance question. when the crank is at t for 1and4, cam end notches are pointing in, the 2 is up for exhaust, 3 up for intake, and chain 20 links apart is the notch on the govenor supposed to be lined up with the contact for 1 and 4 on the signal generator? hope that made sense.