Honda Twins banner

1 - 11 of 11 Posts

·
Registered
Joined
·
179 Posts
Discussion Starter #1
With the engine running, the tachometer needle does not lift off the peg easily, but will after goosing the throttle a bit. Then it will indicate the idle speed and above. In the attached pics, I've marked where I think lubrication might be needed. Question is where and what type of lubrication? A light machine oil (the type used to lubricated electric clippers? 3 in 1? Something special? Thanks.

Inked101419 CB350K4 tach 1_LI.jpg

Inked101419 CB350K4 tach 2_LI.jpg

Inked101419 CB350K4 tach 3_LI.jpg
 

·
Super Moderator
Joined
·
24,208 Posts

·
Registered
Joined
·
6 Posts
I just repaired the same issue on my CB450. The original lubricant gelled up and ended up in the bottom drum causing a clearance(dragging) issue between the lower drum and the magnetic disk. On my CB450, they are at an angle to each other which allowed me to get in with a cotton swab and rubbing alcohol to clean it. However, after I looked closer, I decided to take it apart more and was able to clean it out better. I also followed the detailed instruction in the link below on very lightly re-lubricating the proper spots on the tach. It works perfectly again.
https://xjbikes.com/forums/threads/speedo-and-tach-dissection-with-pics.15303/
 

·
Registered
Joined
·
179 Posts
Discussion Starter #5
This info should prove very helpful. Thanks to longdistancerider and drbsmith.
 

·
Registered
Joined
·
179 Posts
Discussion Starter #6 (Edited)
1972 CB350K4 Tachometer (recrimping the ring)

Okay. Decided not to mess with the operation of the unit; it functions well enough, and I don't want to disassemble it any further. Cleaned the lens both sides, and used a little canned air. Now I need to re-clamp the ring around the outside. I had pried the ring up on the bottom side very carefully to get it apart.

101419 CB350K4 tach ring 1.jpg

101419 CB350K4 tach ring 2.jpg

101419 CB350K4 tach ring 3.jpg

101419 CB350K4 tach ring 4.jpg

I need to re-crimp the ring, with no or minimal marks on the top side of the ring. I thought to make a jig to hold the unit face down in place, and use a piece of PVC with the same ID and the OD of the unit to force the uplifted side of ring back to flat (clamping the upper and lower portions together. Not sure if pressing the PVC down uniformly will yield the best result. Any other ideas are encouraged and welcome. Thanks
 

·
Super Moderator
Joined
·
24,208 Posts
I'm going to be in the same position of clamping that ring down soon. Waiting on new rings since mine are pretty bad.
I'm thinking the PVC pipe to set the gauge into and then peen the ring over with a small tap hammer. Other thought is a pair of duck bill pliers w/o teeth, pretty hard to find, with a piece of rubber/leather to protect the face finish of the ring.
Definitely need some sort of cushion between the gauge and PVC to protect the housing finish.
Looking at some of the photos from different people who rebuild these for a living shows a board with a cutout for the housing to fit in protected with cloth.
 

·
Administrator
Joined
·
13,089 Posts
I think the hardest part of the reassembly is the pressure you have to keep on both halves to keep the soft rubber ring between the halves compressed so the metal ring will lap over the bottom half while you crimp. Mine were so hard to keep together and crimp at the same time that I ended up with permanent trigger finger on my ring finger of my right hand from continuous gripping of the duckbill pliers, probably because I hadn't used that much grip continuously for a couple decades since getting into a softer line of work. My duckbills had worn teeth and though they left some marks on the upper side of the ring, I helped disguise it by taping off the side of the ring when I re-painted the upper half satin black, allowing the satin paint to cover the horizontal upper surface of the ring, and it blends in with the upper cover and isn't as noticeable
 

·
Registered
Joined
·
75 Posts
On GL1000 and CB750F units I've done, I used some cheap racheting bar clamps from Harbor Freight to press it all together and just used regular pliers to re-crimp. Came out looking fine. On all of these, my problem was non-response or very slow response and return of the needle. A partial drop of silicone lubricant gathered on a toothpick from the spray can lid placed carefully on the needle bearing thined out the old, thickened lube and returned normal operation. I didn't mess with the odometers.
 

·
Registered
Joined
·
179 Posts
Discussion Starter #10 (Edited)
1972 CB350K4 tachometer Recrimped

I decided to make a jig and a crimping tool. Jig, tool, and results are below. Can of grease not included in the process.

Jig: compresses the two halves together
CB350 tach crimp jig 1.jpg
CB350 tach crimp jig 2.jpg


Tool: Untapped plier jaw works on the bottom of the ring. Top of ring shows almost no marks from this process.
CB350 tach crimping tul.jpg


Clamp ring reinstalled: worked a cross pattern (N/S/E/W) going very slowly around the ring, one plier jaw width increments.

CB350 tach rng recrimped 1.jpg

CB350 tach rng recrimped 2.jpg

CB350 tach rng recrimped 3.jpg

CB350 tach rng recrimped 4.jpg


Up until now, I have not included many pictures of the progress made on this bike. Combination of forgetful and lazy. Hope to improve. And I hope this post proves helpful to someone else. Thanks for the feedback.
 
1 - 11 of 11 Posts
Top