Topic: CB750 experts - HELP! I can't get my cam sprocket on the cam. I'm stumped.

[markb]

I didn’t want to look stupid by posting this but I don’t care anymore.  I have to figure this out.  I’m trying to get the cam sprocket onto the cam but it won’t go.  I seems like the cam chain is too short.  It’s hard to tell in the photo but it looks like I need another 1/16” to get the sprocket on the shoulder of the cam.  It is a brand new chain.  I counted the links – 94, so that’s right.  I flipped the engine over (oil pan is not on yet) and checked and the cam chain is properly engaged with the crank sprocket.  I double checked the tensioner assembly and that seems to assembled correctly (the tension adjuster is not installed yet).  This isn’t my first CB750 but I must be missing something obvious this time.  Is it possible the chain is too short?  This must have happened to someone.  Please help.  Make me look stupid.  I don’t care.

[Restoration Fan]

Haven't tried to put ours back on yet, but I know we had to turn the cam shaft to a certain point to get it to be able to come off.  So I would assume you have to rotate the cam shaft to find the little indentation that will allow the pattern on the cam sprocket to "match" and go onto the shaft.

[markb]

The sprocket is already on the shaft.  The shoulder on the cam is round.  It doesn't matter where you have the camshaft rotated at this point.  The sprocket just won't lift high enough to get it on the shoulder.

[oldhatt45]

There was another recent thread regarding putting a cam chain back on.
I seem to recall that the answer was (if I remember correctly) that you had to rotate the cam chain from the front of the engine.
If you rotate it from the back, it was too tight.
Now, I could have that backwards, but hopefully one of the REAL Experts will chime in and clarify.

Here is that thread http://forums.sohc4.net/index.php?topic=143232.0

Hope this helps

Charlie

[markb]

I don't know if it matters but that was for a 550.

[oldhatt45]

The Last post on that thread by "setdog" refers to what he did.............. on a 750. 


Charlie

[markb]

I see that now. I'll try it.

[ekpent]

Are you putting #97 together right now ?  What brand of new cam chain in case someone may have some input on that .

[Don R]

I think someone recently had their chain guide upside down or something like that, just a thought.

[markb]

Are you putting #97 together right now ?  What brand of new cam chain in case someone may have some input on that .

It is E100 for #97.

I think someone recently had their chain guide upside down or something like that, just a thought.

It has to be something like that.  I may have to tear it down. 

[markb]

I checked my assembly photos and it appears to me that the cam chain tensioner and cam chain guide are assembled correctly.  Anyone see anything amiss?

[ekpent]

Your the expert Mark but is there any chance that the Sandcast/early K0 cylinder blocks may be a few mm's taller than later year models ??  Block seated well to the cases ??
   Hope you get it buttoned up.  Hopefully an engine builder will chime in for you today.   Eric

[madmtnmotors]

I think someone recently had their chain guide upside down or something like that, just a thought.

Ding! Ding! Ding!

The slider is upside down. The "slip pin" should be on the bottom, long tail sticking up (to protect the head).


http://forums.sohc4.net/index.php?topic=142118.msg1612431#msg1612431

[flybox1]

The sprocket is already on the shaft.  The shoulder on the cam is round.  It doesn't matter where you have the camshaft rotated at this point.  The sprocket just won't lift high enough to get it on the shoulder.

Mark,
I experienced this with my build.
I could get the chain on the sprocket, but everything seemed just a tad tight to get the sprocket to jump up on the cam.
The trick, and it was a suggestion from someone here on the forum, was to swap the order of how I threaded the cam and sprocket into the towers. it worked perfectly.

So lets say you originally threaded the cam in, and at the chain tunnel, you first looped over the chain, and then the cam thru the sprocket.....you'll need to reverse the order and put the sprocket on first and then loop the chain over the end of the cam before threading it all the way thru the towers...
One of these orders works, the other doesnt.  I dont remember which order was correct, but one works, and the other doesnt....
I'll see if I can find my thread about this and post it....

[Swoop]

I think someone recently had their chain guide upside down or something like that, just a thought.

Ding! Ding! Ding!

The slider is upside down. The "slip pin" should be on the bottom, long tail sticking up (to protect the head).

It looks right to me....it has always been a fiddely and time consuming procedure but you eventually fall into it somehow. Keep trying.


http://forums.sohc4.net/index.php?topic=142118.msg1612431#msg1612431

[madmtnmotors]

The sprocket is already on the shaft.  The shoulder on the cam is round.  It doesn't matter where you have the camshaft rotated at this point.  The sprocket just won't lift high enough to get it on the shoulder.

Mark,
I experienced this with my build.
I could get the chain on the sprocket, but everything seemed just a tad tight to get the sprocket to jump up on the cam.
The trick, and it was a suggestion from someone here on the forum, was to swap the order of how I threaded the cam and sprocket into the towers. it worked perfectly.

So lets say you originally threaded the cam in, and at the chain tunnel, you first looped over the chain, and then the cam thru the sprocket.....you'll need to reverse the order and put the sprocket on first and then loop the chain over the end of the cam before threading it all the way thru the towers...
One of these orders works, the other doesnt.  I dont remember which order was correct, but one works, and the other doesnt....
I'll see if I can find my thread about this and post it....

The slider is upside down. The long tail is jammed into the crankcase when in fact it should be sticking out the top of the cylinders to protect the head. Fix that first.

[madmtnmotors]

It looks right to me.

The slider is upside down.

[madmtnmotors]

14611-300-000:




14611-312-000:

[markb]

The slider is upside down.

I don't think I agree.  Are you saying the "slider" (cam chain guide) is supposed protrude up from the top surface of the cylinders?  The second pic above shows that mine is.  Your reference link was for an F2.  This is a K engine.  I think the guide on the F engines sticks out farther than the K engines.

[flybox1]

Mad...he's working on an early K...not an F

[flybox1]

This is a K engine.  I think the guide on the F engines sticks out farther than the K engines.

Correct!

mark..please see my suggestion above

[flybox1]

here's my thread
http://forums.sohc4.net/index.php?topic=136322.msg1534988#msg1534988

...and here's the fix...

Dremel is NOT needed. Chain on first then sprocket with beveled edge facing the center next. Lift chain onto sprocket before sliding sprocket into place. It'd be easier for me to tell you if I had one in front of me. It WILL work. Rotate the sprocket 180 degrees.

[madmtnmotors]

Is the slider new? Do you have a part number or source for the supplier of this new slider? The old slider (short top 14611-312-000) is discontinued from Honda. If you used the late model part 14611-300-000 (it will fit if oriented long-tail up) then I contend it is upside down.

Is the "removable" pin on the top or bottom? The orientation of the removable pin will determine which part you have. I see that the older models have a "short tail" on top with no tail below. If this is a later model slider then the long tail is jammed into the case.

[flybox1]

http://www.cmsnl.com/honda-cb750k1-four-1970-usa_model14354/guide-camchain_14611312000/#.VIXMhnJSh1Y
CMSNL says its still available.

[madmtnmotors]

If it is an older style slider 14611-312-000 then I stand corrected. 

Is the removable pin installed on top or bottom?