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Camshaft Installation....Verification

Wez_

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Hello guys. So the plan is to assemble my top end to see if I have a zero clearance. So what was explained to me is that since I had the valves ground, the valve clearances will be that much tighter, to the point where I might have zero lash. If this is the case, then I am hoping to do a custom shim job once I can get the camshafts installed and measure the new clearances. If I can get 2-5K miles from the work done thus far, well at least I learned how to recondition a head properly (no valve grinding, just light lap and read pattern)

With that being said I have followed the Clymer manual on reassembling the head and installing the camshafts and I am the step where it's time to start bolting down the exhaust cam bearing caps. I don't want to continue until I can confirm a few things.

1.) I cannot fully install the long exhaust cam chain onto the exhaust sprocket at this point. It will not fully engage on the gear teeth (its about 3/4 on).
I pulled up on the chain as much as possible (the tensioner lock nuts were lose and the outer piece of the tensioner came all the way up when I pulled up on the chain. Then I tightened the lower lock nut. Still not enough slack.



2.) The lobes of the number one cylinder are pointed towards the spark plugs, but seem to be engaging the shims and valve train. It also appears If I install the bearing cap A, the lobes of the #1 cylinder will engage the valve springs and open the valves.
The #1 & 4 pistons are at TDC where I left it, also the timing mark is at 1.4T as close as possible.
The cam just appears to be perfectly seated in its bearing groves on the right side, but the lobes are engaged on the left side at #1 cylinder.

3.) It appears if I tighten down the bearing caps, I would have enough slack in the chain to clear the sprocket teeth and full install the chain. Next steps are to tighten the sprocket mounting bolts and rotate the assembly counter clockwise a few times to install the other sprocket bolts.


I hope I am doing this correctly. Please advise.

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There is no one right way to do it. Tightening the caps does indeed push the valves down and if the pistons are at TDC how you bend the valves. I myself never use the service manual method but then too hard to explain, it requires changing up the procedure second-by-second. Can't be done without total familiarity with how the engine works and can't be taught in 10 minutes. I put pistons all in the middle and even and then tighten cams down and then slowly sneak up on the overlap. It doesn't bend valves but very hard for rookies to understand.
 
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http://www.cb750c.com/modules.php?name=Your_Account&redirect=viewtopic&t=301

Go there, enroll for free and look up the Honda service manual section (in technical documents) on cams..............yes, when you tighten the caps the valves are being pushed down, the aim being to make sure the pistons are not in the way of the valves as they come down. That's where most mistakes are made.

Don't tighten the caps that tighten down all the way easily, do them all evenly to pull the cam down in parallel to the head, if not then you can damage the cam side location groove as the cam enters it crooked, can even break the cap there.

DON'T tighten the caps overall to the book spec either, it's too high and often the bolts break doing it. 8 MAX there. Can strip the head threads at 10.

You cannot rotate the crank at all until the cams are BOTH positively located once the caps are tight, doing so is how most valves get bent. Only do it when the manual says to.
 
If i use the manual's method for installation, will there be enough clearance for the number 1 valves to open up as the caps are tightened while the #1 piston is at TDC? It sounds as if you explained that this bends valves but it also sounds like the instructions are telling me to do this....
 
What I'm getting at his probably the spec for valve opening dimensions. The combustion chambers are roughly 1/2" deep. How far do the valves open up when the caps are tightened? More or less than the cc depth? Enough to reach the piston when the caps are tightened or should there be slight clearance between the valves and TDC piston? Thanks a million.
 
You must follow the manual procedure EXACTLY.

At TDC the valves are only open a little bit but the piston is right there for them to hit it. Maximum valve lift is not the issue as that occurs with the pistons way down in the cylinder to not hit. It's overlap that kills you, the period around TDC where both valves are open just a little bit but they are following the piston top VERY closely.

'...should there be slight clearance between the valves and TDC piston?'

Yes but why you must be dead on and not move the crank doing it other than what the manual says. Either way unneeded at TDC and you bend them. There's only maybe 50 to 100 thousandths of an inch clearance there to either valve. Why you don't go whirling the crank around. Do things in EXACTLY the order said there.

Done correctly, the positioning puts the valves right in the pocket in space they need to just barely clear.
 
At TDC the valves are only open a little bit but the piston is right there for them to hit it. Maximum valve lift is not the issue as that occurs with the pistons way down in the cylinder to not hit. It's overlap that kills you, the period around TDC where both valves are open just a little bit but they are following the piston top VERY closely.

'...should there be slight clearance between the valves and TDC piston?'

Yes but why you must be dead on and not move the crank doing it other than what the manual says. Either way unneeded at TDC and you bend them. There's only maybe 50 to 100 thousandths of an inch clearance there to either valve. Why you don't go whirling the crank around. Do things in EXACTLY the order said there.

Done correctly, the positioning puts the valves right in the pocket in space they need to just barely clear.[/QUOTE]

GOT IT!!

Also, can I rely on the 1.4T mark to accurately determine that the piston is at TDC? I assume I can also place like a long screw driver with tape on the end to protect the piston in the spark plug hole and verify that when the 1.4T mark lines up with the pointer....is point where the screwdriver movement reaches it's maximum? (@TDC)

N MAKE DAMN SURE I FOLLOW EACH AND EVERY DAMN STEP OF THE MANUAL TO A T....

PFFF..im actually pretty nervous but I think I can handle this.

Thanks AMC...really...If I get this thing running, let me send you a 6 pack of IPA
 
Also, can I rely on the 1.4T mark to accurately determine that the piston is at TDC?

Yes, don't second guess it. It means 'cylinders 1 and 4 at (T)op dead center'.

Turn any crank movements lightly and if you encounter any sudden lockdown !!STOP!! instantly. All spark plugs removed so no compression to fool you of course. The problem being that with the leverage you get with a socket or wrench on the alt rotor you can bend valves much easier than you think. You can actually bend them by not even touching pistons, the valves hit each other on the edge if both are lifted too far at the same time. More fun.

I've done that stuff on a hundred different engines and I even go very slow and nervous there, I HATE f-ckups! You have no idea. Try it on variable cam timing motors like they use now where you have no idea where the valves are at due to them moving all over the place even with the cams locked down. It's crazy. I had to develop one-off procedures for me at least to stop all the errors that occur by following the super simple made for idiots service manuals like for Fords with VCT. People argue with me all day long but being able to sort that out at 100% accuracy speaks for itself but it gets very complicated. I don't follow those official procedures at all either, other than all I need is the timing points themselves. The sprockets spin loose and don't have any keyways or locating at all. There are ZERO cam timing marks or TDC marks as well. Insanely stupid but it protects dealer work when nobody else can do it right. You are lucky to have accurate marking there.

The service manuals now assume people of lesser experience doing the work, it allows for all kinds of timing mistakes that pop OBD error codes at the drop of a hat and no resolution for it other than the manuals say you didn't do it right but can't tell you why. Yet you still have to have TDC and two cams timed as well as the two variable valve mechanisms too. It gets nuts quick.

The world of the future................the less the general public can do the more work they force into the dealerships.
 
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Wow...thats messed up if you ask me. I'm glad I enjoy bringing relics back to life. What you just described sound annoying. So what do or did you do for honda motorcycle professional work?

I used a two way drill bit adapter as a dial indicator (rested my finger on it and used my focused laser alignment eye) whule rotateing the crank and aligning the 1.4T mark...

It appears the piston is starting to actually go down at 1.4T..

Is this accurate movement?
 
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Something is definitely wrong.

I need to know if the long exhaust cam chain is supposed to be completely installed on the sprocket or not before the first initial rotation of the crank. The manual says that I have to keep the chain meshed while rotating the assembly counter clockwise in italics like it's some tribal knowledge key step.

But my exhaust cam chain is like 1/2 installed on the sprocket.

Following the manuals instructions, it's not clear if the long exhaust chain should be fully installed on the sprocket. I cannot get ANY more slack in the chain so it fully installs on the sprocket, while being able to get one bolt started to mount the sprocket to the cam.

I secured the bearing caps down nice and evenly, the cam alignment marks seemed to better align with the top of the block more also...but...

The cam chain binds harshly because it is only half way installed on the sprocket while doing the first counterclockwise rotation...

I didn't go any further, and loosed the bearing caps

Please advise...
 
Why I told you to download the Honda service manual section on it, the aftermarket books are lacking in some respects. The exhaust sprocket is not installed 100%, the manual states that. You must have the chain tensioner at 100% collapsed, 95% is not enough and remember how it came apart too, there was a bit of interference taking it apart there. Why you gotta pay attention.

The tensioner end has to be up as far as to hit the stop and the exhaust chain must still be centered on the sprocket down below on crank. The head must be torqued down too.

The chain must already be fitted on the sprocket fully before trying to pilot sprocket to the cam, having sprocket on cam first will not have enough clearance to jump the chain the rest of the way over the top of sprocket. The exhaust cam does NOT install fully first. Even with all that there is often a bit of finagling to do to get it all.

Page 94--bottom half of page, section 6-20.

If you are at TDC then any more movement at all will be going down as the going up movement has already expired.

I have no formal training in Honda or any other brand at all and never worked for them and how I ditch OEM ideas by the hundreds with no 'you can't do that' echoing in my ears. I gained by working at the family garage and building lots of drag race car stuff and working on every brand of Japanese bike pretty much known to man. Plus 35 years of working on huge web offset printing presses where I often repaired them as well. The Ford stuff comes from working on my own cars, I never let anyone work on my cars, only me. Been that way for 40+ years. Same with most of the bikes, I owned entire streams of them and hotrodded them a lot.
 
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Why I told you to download the Honda service manual section on it, the aftermarket books are lacking in some respects. The exhaust sprocket is not installed 100%, the manual states that. You must have the chain tensioner at 100% collapsed, 95% is not enough and remember how it came apart too, there was a bit of interference taking it apart there. Why you gotta pay attention.

The tensioner end has to be up as far as to hit the stop and the exhaust chain must still be centered on the sprocket down below on crank. The head must be torqued down too.

The chain must already be fitted on the sprocket fully before trying to pilot sprocket to the cam, having sprocket on cam first will not have enough clearance to jump the chain the rest of the way over the top of sprocket. The exhaust cam does NOT install fully first. Even with all that there is often a bit of finagling to do to get it all.

Page 94

OK, Ill get on downloading that manual and get some better images and read the reassembly from Honda. Hope I haven't lost your help by not following these helpful tips sooner...I did register, but haven't downloaded / read the manual.

I knew this step was gonna be tricky....
 
No, no, everything is cool. I just don't really follow that procedure...........I mean I may start but the 'just can't leave it alone' in me has me changing things up almost instantly. Add to that it's 500 page book stuff anyway if pointing out everything that can go wrong and you see the problem.

I'm tryin'.

Tryin' mainly not to overload you with stuff that will confuse you even more even though it's dead clear to me. Sometimes saying too much is just that.

And don't let any of that higher up sway you, I can be just as full of crap as anyone else. It just doesn't happen real often. Hopefully because I look for it quite a bit.
 
Ok, cool....

Are the valve springs directional? I keep seeing references to one side being different and installed toward the head. I could not identify any difference between each end. Perhaps I just didn't know what to look for. But they all installed nicely.
 
Well..I may have to disassemble each valve again....The Honda manual better explained that the coils are more tightly bound on one end....rookie mistake....

Will I have messed up the springs potentially if they were installed up side down?
 
No harm and yes flip them if needed. They dissipate heat better to the head the right way, and the lighter wound end is less weight allowing for more rpm before valve float. Main thing is not to compress the spring anymore than necessary to get the locks in.

Have you compressed the head gasket by torquing it yet? You can't do that and then remove it to use again. One time use there.
 
Yes, the head gasket is the original. This is sort of experience and practice. Also, i need to mock up the assembly to check valve clearances since i had the valves ground....the clearances are likely much tighter. Will the head gasket throw off valve clearance significantly?
 
You check the valve clearance with the head off the bike. It's the clearance at the cam/tappet you are checking, not valve to piston which will clear with OEM parts if the cams are in right.
 
After using the suggested Honda service manual, I was able to better install the exhaust cam.

Only problem is with the alignment notches in the left side of the cam. The notches seem to be slightly off when at 1.4T (camshaft assembly slightly rotated towards the spark plugs)

You can see this if you open the third image from my original post in a different tab.

Any suggestions?
 
It is no longer that much off (Ill get a new image after work) but that image is an exaggeration of the misalignment as the cam caps are not tightened down in that image. But the camshaft went straight down from that point and the resulting notches are slightly off.
 
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