Tach Drive Oil Leak

My tach drive has always leaked a little, gets the #3 exhaust collar dirty.
So I changed the fancy seal in the drive unit, and I changed the o-ring around the body of the unit. Cleaned the motor up, and rode into work today.
Now there's a puddle on the ground, the size of a silver dollar, under my tach drive.
This leak is hard to fix, at least on my bike.
Does anyone have a secret fix for this leak? I'm thinking about just getting a new drive unit, but my old one looks fine.
Help!

Here's the drip:

If you didn't damage the oil seal when installing it or sticking the drive part through, then I would look for a different drive part. There are only two ways oil can get out... around the outside where the oring goes or past the seal. If you still have leaks after installing a new seal and oring, then the drive itself must have some irregularity or scoring. I have seen "kits" which included the metal part. Not sure where... maybe Z1enterprises.com but I have definitely seen them on eBay. Put some grease in the hole where the metal parts slips in... it should go in TIGHT.

Yeah, I lubed the o-ring with engine oil, and it went in tight. I'm sure I didn't cut the o-ring when I installed it.
Z1 has a replacement unit. Maybe I'll order it.

WG's fine perspective aside, one other possibilty comes to mind - and don't get me wrong, I've done it myself - are you certain the oil quantity/level is proper?

Too much oil getting pumped up into the cam chunnels might be forcing it to take the path of least resistance. I'd expect other symptoms as well - weeping at the cam inserts and puking at the breather, but hey, seen weird stuff before...

Nice looking motor, BTW...

I'm sure the oil level is fine.
BTW, when I took off the old o-ring, it was like a piece of hard plastic. Not elastic at all, and I had to break it to get it off. I think it's just a buna or neoprene o-ring ($2.50 from Kaw), and it's definitely not rated for the temperature. I was going to try a silicon o-ring, it's better at high temp, but silicon is not compatable with petroleum oil. So I just ordered the o-ring from the parts catalog.
I'm going to try to run it (in neutral) with the cable disconnected. Then maybe I can tell if its leaking thru the seal, or past the o-ring.

It seems to me that oil would return down the oil galley in the center of the engine (the long well where the cam chain rides) and it would be pretty hard to have excess oil accumulate. The hole over to the galley is right by the drive on #3 depression in the head. Excess oil would likely blow by the rings if there was really too much and more likely to come out the crank vent.

I think the oring in a Versah gasket kit for the tach drive is the green one. I believe nitrile rubber would likely be best for sealing oil.

ltdrider wrote:

Does anyone have a secret fix for this leak?

Yeah, I do, but then it wouldn't be a secret anymore.

:pinch:

Your post reminded me that I need to get the part number for the faucet washer I got at ACE hardware. . .making mental note to self. . .while scribbling on forehead. . . .41 cent part fixed mine seems like months ago.

LTD, just wanted to note that your bike is very sharp. from your pics all around here that bike is extremely clean. very nice, im jealous!

Hi, I'm back from ACE and have the number for the washer that FIXED my tach-seal leak.

It's a 3/8" medium flat washer. Flat on both sides, no bevel.

#4099701 is what the guy wrote down on the paper, so if he wrote it wrong, yell at the ACE guy. Yep, I'm re-checking the number. . .4099701. I think the washer starts out life as really hard and purple.

Looking at the the picture might help.


The packing (#16) that normally gets pushed down by the tach cable sheath gets compressed over time, and eventually the sheath looses the seal it needs to keep oil from migrating. So to build up the packing level, I used the ACE washer between the existing packing and the cable. It's a drop-in replacement. You won't have to tighten the cable too far to acquire the seal. If the leak ever comes back you can still tighten it some. Elegant fix. Way cool, no drool.

:woohoo:

KazooCruiser:
Until just now, I didn't even know that there was a gasket in the tach cable connector.
I just thought that the tach guide seal & o-ring kept the oil from leaking out, and nothing further should be req'd.
But sure enough, the Parts Breakdown for a KZ900 shows a gasket. Looks like I'm going to ACE!
Thanks bud! I owe you a cold one!
Tim

Thinking gasket in the tach cable connector serves primarily to keep lube inside the cable from escaping. If the cable was "re-lubed" and attached without the gasket, some of the fresh lube could be escaping from the knurled knob area.

Concur with idea of closely watching area with engine running and tach cable disconnected at the engine end. If o-ring and shaft seal are okay, no engine oil should escape from the tach drive unit.