TOPIC:

As I'm running down the many issues plaguing my 78 KZ650B, I've noticed a pretty significant oil leak from the base of my speedometer cable. What am I getting myself into addressing this? Thanks.

Speedometer or tachometer? To my knowledge there's nothing to leak from a speedometer cable, but leaks from the cylinder head where the tach cable attaches are common and very easy to correct. Ed

Tach... left my brain at home

Common problem and easy fix. Replace parts marked 13, 15, and 16 in diagram below. Ed

Here's a link to some helpful info:
Click here > www.kzrider.com/forum/2-engine/596113-tach-seal-leak-won-t-stop

Good Fortune!

Also almost every KZ has had the cable replaced multiple times by now, and originally there was a paper gasket like donut shaped, that sealed the cable to the drive. The orings and seals pictured previously seal the drive to the head, but also a paper gasket is used that is never shown on parts lists and gets thrown out when the first cable is replaced inadvertently. I made a gasket and it fixed my leak.

There is no leakage from the drive, unless the seal or o-rings are damage..
What happened to mine is the old seal wore a groove in the shaft with the gear on it that engages the cam to drive the tach.. a new seal didn't seal on this worn area ... that have this tach drive at Z1....

That can happen. When I fixed mine I replaced all parts numbered 12-16, but then I'm a bit of an overkill type. I probably didn't need 12 or 14. Ed

ezrider714 wrote: There is no leakage from the drive, unless the seal or o-rings are damage..
What happened to mine is the old seal wore a groove in the shaft with the gear on it that engages the cam to drive the tach.. a new seal didn't seal on this worn area ... that have this tach drive at Z1....

This is probably true for me too, as my tach seal leak was on an engine that had 80,000 miles on it in 6yrs use, which I thought was quite a bit back in the day, but nothing by today's standards. Anyway, the seal and/or shaft is worn, letting oil past into the cable. This can all be fixed by adding a paper gasket that was there from the factory, but not ever published officially as a part. After I made the gasket, all oil that leaked through the seal/shaft was confined by the gasket and not left to leak. Just a round paper gasket sealing the cable to the drive.

Even without the tach cable installed, there should be no leakage whatever from the tach drive, either through it or around it. And after a cross-country ride without a tach cable, the exposed end of the tach drive shaft should be perfectly dry and oil-free.

Without the tach cable attached, one may observe the end of the tach drive shaft and watch it spin when the engine is running.

When oil is escaping past the tach drive shaft seal, the using of a gasket inside the knurled knob to create an oil-tight connection between the cable sheath and tach drive housing simply allows the escaping oil to accumulate inside the cable sheath. Certainly better than nothing, but is simply containing oil that's not supposed to be escaping.

When oil is escaping around the tach housing by getting past the o'ring that's supposed to prevent leakage between the housing and engine head, the oil will leak onto the engine fins and not be contained inside the cable sheath, because the oil leakage is outside the knurled knob.

Good Fortune!