• Don't overlook our Welcome Package, it contains many links to important and helpful information about functions at VHT like posting pictures and sending PMs (private messages), as well as finding the parts you need.

    AD

CL77 left cam lock nut removal tips needed

Flyin900

Veteran Member
Joined
Nov 28, 2020
Total Posts
1,706
Total likes
654
Location
Canada
I am into the head today and have the head down to the cams and cannot seem to get the lock nut removal happening. I can turn it both directions somewhat with a drift, yet experience is needed here. Anyone have the answer? Any better solution for the tool to turn that weird nut face?

The cam is supported by 4 main roller bearings, so any tips there in removal of these bearings as they sound a little sketchy.


Cam lock nut pic:

P1070888_LI.jpg
 
Remove the end caps and rocker shafts from the head, then use a brass drift and a hammer to loosen the nut. Then use that brass drift against the inside edge of the cam lobes to work the camshaft and bearings out of the head. On the other side unscrew, outer end, unscrew the nut until it's flush with the center bolt then give it a couple of gentle taps inward to release the taper on the sprocket end of the cam. Use a couple wedges against the side of the sprocket hold it in place while removing the other cam. When it goes back together, there is an index mark on the points cam that needs to be lined up with the "0" mark on the sprocket for the ignition timing to be correct.
 
The FSM leaves a lot to be desired but looking at it and parts diagrams it appears the cam nut is on a bolt with a tapered head and sounds like the taper is slipping. I'm assuming here that you're talking about #32 in this fiche https://www.partzilla.com/catalog/h...-with-no-year/cl77-a/camshaft-valve-cam-chain
Maybe a air 3/8" drive impact gun?
Looks like the bearings will just press off/on once you get the camshaft separated into it's 2 pieces.
 
Mike,

Thanks for the tips as you have clearly done this before. My issue with the cam nut is which is the correct way to turn it? Is it lefty loosie like most nuts and bolts? In my picture in the post the cam nut is on the right side, so would I drive down that raised edge on the nut turning it left in effect, for a normal off procedure?
 
Thanks it came apart with the righty tighty design on the threads. I am stuck with the other half in the head and not wanting to come apart. I removed the nut and washer and then put the nut back on and tapped with no separation. I have tried to punch inside the shaft with a drift and the cam bearing popped out, yet no separation of the cam and main gear.

Thoughts?

Pictures:

P1070950.jpgP1070951.jpgP1070952.jpg
 
With the nut loosened, is the center bolt loose? With the nut tightened, the tapered end of the rod expands the end of the cam to a tight fit in the sprocket. It might take a pretty good whack to get the bolt out of the taper. Set the nut flush with the end of the bolt and hit it square, so you don't ruin any parts.
 
The bolt is frozen in the shaft. I have tried heating the shaft area and hitting the interior of the geared shaft from inside the cam gear to try to push it off the cam chain sprocket with no joy there. I haven’t tried to really hit the nut and threaded bolt end hard yet. The biggest issue is the one remaining bearing moves easily with the attempts to whack anything in either direction. I used a bolt socket in the gap inside the head to jam the bearing from moving now.

So where should I be concentrating the effort to separate the cam from the gear?
 
Hitting the inside of the cam sprocket hole is likely to damage the advance mechanism. It can't come apart until that center bolt is loose. Look at # 24 in the diagram:https://www.partzilla.com/catalog/h...-with-no-year/cl77-a/camshaft-valve-cam-chain , it has to be driven inward(so it's loose) to release the cam from the sprocket assembly. I use a couple of small wooden wedges between the sprocket and the head to hold it when I tap the camshaft out.
 
Mike,

Thanks I spent the day yesterday getting the head apart and finished it this morning by getting that bolt to release finally and the cam out. I removed all the valves and have the head soaking in a degreasing solution. Lots of dirty sludge and carbon in there.

I will replace all the roller bearings, as think every bearing has some contamination from poor maintenance early on in the bikes life.

I ordered a .50 over IMD piston kit from England, plus a complete set of OEM valves (Shin Nippon) and found a complete full OEM engine gasket kit online too. So after the holidays I will work on getting the cases Vapor Blasted and the carb bodies too. Hopefully my fellow member's machine shop can do the work and I can learn a thing or two about that process.
 
Be sure to check out the cam sprocket assembly for loose rivets and stretched out springs in the advance mechanism while it's apart.
 
The cam sprocket assy should NOT be washed in a degreasing solution ! The little dampers of the ignition advance unit are made of neoprene, and will get loose and finally work them self from the pin. If this happens, not only your engine will make a "clacking" noise but the ignition timing will change.

Furthermore, when heating the cylinder head in an oven (+/-150 deg Celsius +/- 300 degrees Fahrenheit), the bearings will come out easier, and new bearings will fit tighter in there housing.

btw, it's a pitty that the Honda305.com website is not active any more (and for me unreachable). Lot's of info there, also from me (before I started with the 450's 7 years ago, I was specialising for 20 years on the CB72/77 and dreams. I have a CB72 of every year these where build, starting from 1961 to 1967 plus a few CB77's and dreams.

As I recall, it should be a right-hand thread.

Yes, most are, but some are not, I have them both NOS (I recall that these were early)

P4120027.JPG
CB72/77 hawk/superhawk sprocket with advancer

P4120029.JPG
C72/77 dream sprocket with advancer

P4120033.JPG
Early type C72/77 dream sprocket with advancer + weights for smoother running (360 degree engine)

P4120031.JPG
CB72/77 thread which is right handed
P4120032.JPG
C72/77 early advancer thread which is left handed

btw, sorry for all this info, miss the honda305.com.
 
Jensen,

Thank you. I found the defunct HONDA305 site; which I was able to read some items I believe on there. I have the cam sprocket bagged with no solvent cleaning done, yet I did heat the boss area in an attempt to get the bolt to move in there.

I will check the pins closely and may purchase a complete NOS assy if available reasonably priced.
 
Hi,

These parts are not reasonable priced, but can be fixed.
If you where planning to go E-ignition, you could think of buying a unit with E-advancer.
This way you can dismiss the mechanical advancer (and tag-weld the weights of the advancer).

I dis-assembled many CB/C 72/77 engines and found lot's of welded ones in full advance position....

Jensen
 
The bike actually came with the Probe Engineering electronic ignition set and the original points plate and points set up too. I checked the advancer and the springs are taught and seem equal on their return pressure. They are not sagged out in my limited experience on this style of advancer. When I grab the slider plate the springs attach, which pivot on those neoprene bushings there is very slight lateral movement on the one arm when pushed side to side and the other is quite solid with no real movement.
I can't imagine this set up is super critical as everything else will have some wear. I would expect and the timing is likely better with the electronic arrangement.


P1070945.jpgP1070936_LI.jpgP1070944.jpg
 

Attachments

  • P1070934_LI.jpg
    P1070934_LI.jpg
    104.7 KB · Views: 12
Hi Flying900. I believe the tolerances in the advance assembly are super critical. For example, when one side of the neoprene stop was worn, the variation between idle and full advance became too great in my cb77.

If I adjusted the timing at idle, the engine seized on long uphill rides. When I adjusted for proper timing at full advance, it was very difficult to pull away from a stop because of retarded low rpm timing.

The fix for me was to have Tim (305 site) replace neoprene with metal cylinders and redo the rivets with a more robust setup. Any additional clatter was hidden in the overall engine noise, at least in my case.

Best of luck to you, and congratulations for getting the cam apart and all those bearings hammered out. That’s not easy!

By the way, congratulations to Mike. His description of the process is the most concise I have seen. Well done!

Larry near Pasadena
 
Hi Flyin900, I also have that bolt 'stuck' in sprocket /advancer end of tach cam. How did you get the bolt loose? Thanks.
Mike,

Thanks I spent the day yesterday getting the head apart and finished it this morning by getting that bolt to release finally and the cam out. I removed all the valves and have the head soaking in a degreasing solution. Lots of dirty sludge and carbon in there.

I will replace all the roller bearings, as think every bearing has some contamination from poor maintenance early on in the bikes life.

I ordered a .50 over IMD piston kit from England, plus a complete set of OEM valves (Shin Nippon) and found a complete full OEM engine gasket kit online too. So after the holidays I will work on getting the cases Vapor Blasted and the carb bodies too. Hopefully my fellow member's machine shop can do the work and I can learn a thing or two about that process.
 
Hi Mike, have read your helpful tips before. I have a tach cam sprocket/advancer lock bolt 'stuck' in cam. Tips on how to loosen that bolt? Thanks for your help.
Hitting the inside of the cam sprocket hole is likely to damage the advance mechanism. It can't come apart until that center bolt is loose. Look at # 24 in the diagram:https://www.partzilla.com/catalog/h...-with-no-year/cl77-a/camshaft-valve-cam-chain , it has to be driven inward(so it's loose) to release the cam from the sprocket assembly. I use a couple of small wooden wedges between the sprocket and the head to hold it when I tap the camshaft out.
 
Hi Flyin900, I also have that bolt 'stuck' in sprocket /advancer end of tach cam. How did you get the bolt loose? Thanks.

Lots of messing around was the trick. I had multiple issues to contend with such as all the bearings moving in unison when tapping on either cam for removal. Mike notes to wedge the cam. I don't remember what actually worked for me. You do need the get the opposite cam out for sure first to open up the cam sprocket area.
My large nut on that side cam section was reverse threaded which was a peach to discover. :)

The bolt in question has a wedge style head that is pulled into the cam and sprocket to lock it in place when that outer 10mm nut is tightened on the outer cam shaft.
I tapped it loose finally and then worked on removing the cam section from that main cam chain gear. One of the worst parts of disassembly I am afraid. It was a month plus ago so it isn't fresh in my mind anymore.
 
Back
Top Bottom