What did I do wrong

[Bob Shaw]

I sent an earlier post but apparently didn't go through. I have a 1982 gs850g. With the cams out the engine turns over just fine. However, on this cylinder head the cam chain guide #2 is not there. The bolt holes are plugged so I guess it was not needed(I receive a post+ earlier on this). I do not know what year bike this cylinder head came off but everything matches up. My problem is this. Following the manual, I swapped out everything from my old head to this one. Buckets, lapped the valves, no leaks, New valve guide seals, valves seated and instaled, new head gasket, and all assembled. My front cam chain guide is installed and fits properly. I followed the manual for putting the cams in, exhaust first, arrow facing forward, 20 pins on the cam chain between exhaust and intake sprockets, idler cam installed, can chain tensioner installed with set screw backed off 1/4 to 1/2 turns . When all is said and done, I tried turning the engine over manually from the crank. It wouldn't budge. I started to back track and removed the cam chain tensioer, no good, the idler, no good. When I loosened the intake cam the engine would rotate but very tight. I now have both came out and holding the fam chain the engine rotates freely. Sorry for the lengthy message, but what did I miss.

[fastbysuzuki]

I have read through your post three times and I cannot think of anything else other than for whatever reason the cams are tight in their journals or the valves are somehow contacting the pistons.
the cylinder head is from a later model but as far as I know other than the difference you describe it should be the same.
it may be a good idea to remove the head take the valves out and install the cams and see if they are tight just to clarify are you using your original cams?
another thing is has the new head been skimmed down to far by a p.o

[hampshirehog]

Are the cam caps you are using matched to the cylinder head? They are line bored together and if yours aren't a matching set the cams might be being held too tightly.

[Bob Shaw]

I am using the original cams from the old head as well as the caps. I have not had the head milled. I had the bike running and then I lost a cylinder so I took everything apart again and started over. I did not remove the head. That will be my next step. Thanks for your input... PS: If the cam caps are not in line with the cams how do I rectify that??

[Steve]

I have a 1982 gs850g. With the cams out the engine turns over just fine. However, on this cylinder head the cam chain guide #2 is not there. The bolt holes are plugged so I guess it was not needed.

I just checked the parts fiche for all years of the 850 that were available in the US ('79-'83), that part exists in all of them. I also checked all years that the 8-valve 750 was available ('77-'79), because the 850 was based on the 750. It exists in all of them, too. I'm wondering who decided it was not necessary and plugged the mounting holes. However, that would not cause your current problem.

I do not know what year bike this cylinder head came off but everything matches up.

If EVERYTHING matches up, you will have either an '82 or '83 cylinder head. The earlier 850s and the 750s used 16 bolts to attach the cylinder head cover, they changed that during the '82 model year run to have 19 bolts. The bolt patterns do not overlap enough to interchange. The '82 heads were silver, the '83 heads were painted black.

My front cam chain guide is installed and fits properly.

It can be a bit tricky to get the bottom of the guide to seat properly, but the top will not seat properly unless the bottom is also correct, so that should be good.

I followed the manual for putting the cams in, exhaust first, arrow facing forward, 20 pins on the cam chain between exhaust and intake sprockets, idler cam installed, can chain tensioner installed with set screw backed off 1/4 to 1/2 turns .

There is one step that needs to happen before this. Hopefully you actually did it and only forgot to mention it. Before installing the exhaust cam, you need to set the crank to TDC 1/4. If you neglected this step, there is no telling where the pistons would be, the valves may be locking them up when the cam is brought down and valves are pushed down.

When I loosened the intake cam the engine would rotate but very tight. I now have both came out and holding the fam chain the engine rotates freely.

This makes it obvious that there is a problem with one or both cams. Try again, making sure you start with the crank at TDC 1/4.

Sorry for the lengthy message, but what did I miss.

No aplogies necessary for describing the problem. I feel it was well-stated, no rambling, nothing that did not seem to belong there. Sure, it took a few words to describe the problem and what you have done, but it was well done.

.

[johnod]

I think the TDC thing that Steve mentioned.

[Bob Shaw]

There is no direct timing mark but an F a line and a T on the disc on the end of the crank. I bring #1 and #4 to TDC and the disc lines up on the line between the F and T which is lined up on the left blade of the igniter. I hope this makes sence. As I tighten down on the exhaust cam I check to make sure the timing mark and the arrow pointing forward on the cam sprocket have not moved. It was mentioned earlier the my cam caps may not be matched to this particular cylinder head. I don't know how to rectify that unless I make shims out of aluminum foil and place the under the cam caps until I have a clearance??? I did notice that my problem seems to be with the intake cam not the exhaust. Thanks for everyone's help.

[Bob Shaw]

I have tightened all cap bolts on both exhaust and intake cams. No movement. I backed off 1/4 turn on the cap C&D and the motor rotates freely. Am I safe with the bolts backed off 1/4 turn. I also put lock tight on the bolts.

[chuck hahn]

Do you have the caps on the right journals?? Note they have corresponding markings. A B C D. They MUST all be on the correct journal or the cams will bind up. And NO its not ok for any bolt to be backed out 1/4 turn. Find the problem and do it right.

[GregT]

Do you have the caps on the right journals?? Note they have corresponding markings. A B C D. They MUST all be on the correct journal or the cams will bind up. And NO its not ok for any bolt to be backed out 1/4 turn. Find the problem and do it right.

And please don't use Loctite on the bolts. Great way to break them in the hole.

[chuck hahn]

And the caps have to face the right direction as indicated on them

[Bob Shaw]

All the caps are on the right journals, facing the right way. When I tighten them down to 7 foot pounds motor won't rotate. Could a shim be placed under the caps due to the fact I'm using a different cylinder head? Please read my earlier comments.

[Steve]

Could a shim be placed under the caps due to the fact I'm using a different cylinder head?

Are these the caps that came with the 'new' cylinder head?

If these are caps from your old head, ... well, there's no other way to say it, ... you're screwed.

.

[headsbikesmopars]

Are you using the alignment dowel pins when installing the cam caps ? I believe the cams are tight because the cam journals (caps) are wrong for the heads or have been dropped , does not take much to push the ID of cam caps a thousandth or two. I have used a wheel cylinder hone to'hone' the ID a half a thousandth or two if that is the issue that method will fix it. Torque the caps in place without the cams and measure the ID in couple places and measure the camshafts journals themselves and you will know. If you do use the wheel cylinder hone , go slow and use some spray oil as you go . Do one journal at a time . Hone a few seconds and retry after, it will take some time but you will get there. When you clearance one move on to next and CLEAN as good as you can . This is best with the head removed . If you have another set of cams you could try them to verify its the camshafts . Keep us
informed as to what you find.
Terry

[Bob Shaw]

Unfortunately I am using an old cylinder head. These are not new caps either. They came from my old cylinder head as well as the cam shafts. I have the dowels in place for each cap. I'll try the brake cylinder hone. Thanks!