Leak from tachometer cable fitting on head of 81 Seca 550

Yep, there's a leak there that only manifests itself when the engine is running. Not a gusher, just a slow drip.

I undid the nut on the end of the cable, then tried to get the fitting off of the head in hopes of replacing an o-ring or gasket to fix the leak...but the fitting that the cable attaches to wouldn't come out. It's a mechanical tach, so I'm assuming that the fitting in between the cable and the head is actually a gear that is meshing with the exhaust camshaft.

Do I need to remove the valve cover and free up the exhaust camshaft to get that leaking fitting out of there? Or is it just a matter of manually rotating the engine and pulling on the fitting? I did undo the set screw holding the restraining strap on the outside, by the way.

Any help appreciated....

 

My guess would be if it does not come out then the o-ring is already sealing and holding it in. They should just slide out turning the spiral drive as it comes out. The leak is more likely coming through the centre of the drive which IIRC does not have an o-ring inside.

Try getting an oring to fit between the threaded bezel and the flat flange on the cable.

They are known to leak a little and most manage to live with it.

 

Re: Leak from tachometer cable fitting on head of 81 Seca 55

Thanks for the advice...I'll try the o-ring fix.

 

Did you ever fix this? I have a little oil seep at my tach cable connection as well. Nothing serious, just a little build up around it.

 

Re: Leak from tachometer cable fitting on head of 81 Seca 55

I think I fixed it, but I'm not sure. I put an o-ring around the flare on the end of the cable where the nut pushes on. I'm pretty sure that's the problem area.

I wish I could tell you what size o-ring to use, but I didn't know so I just grabbed a bunch of likely-looking o-rings at the hardware store. Go for one with a fat cross-section, if possible.

I ran it briefly after installing it and it didn't leak, but I haven't run it on the road or for any length of time, since I've got the tank and other stuff off in preparation for paint.

 

Re: Leak from tachometer cable fitting on head of 81 Seca 55

That entire fitting DOES in fact come out of the engine, and it's actually 3 pieces with washers inside -- those are what's leaking. It's called the Tachometer Gear, and here's a picture of it from the microfiche (linked because it's a big image):

Tach Gear

#2 and/or #4 are the ones that are leaking. I've replaced them on my bike, but for the life of me I can't remember the trick for getting the damn thing out now. Once I had it out, it was easy to go to a hardware store and find off-the-shelf replacements.

 

Re: Leak from tachometer cable fitting on head of 81 Seca 55

Yeah, I've had that whole assembly out of the head and apart. I replaced the o-rings in there and it still leaked.

And the trick is to just gently pry the housing out little by little. It feels like it won't come out, but I think the gear just needs to turn a little as it's coming out, and that's what makes it feel so tight.

 

I may end up pulling my gear drive on there and replacing the o-rings.

Just out of curiosity, would it be too difficult to convert to an electric tach? Just plug the hole in the head and connect a tach to the coil primary wires somewhere? Or is there something more involved that I am overlooking?

 

I've done the internal seal and the o-ring on my 650 twice in a row and it never fixed the problem, even after polishing the shaft. I simply learned to accept it and clean it up often.

 

Re: Leak from tachometer cable fitting on head of 81 Seca 55

Robert, I'm pretty sure that putting that o-ring on just behind the lip of the flare at the end of the tach cable has fixed it. I just haven't had it at full operating pressure yet. However, I used to have a tiny puddle under the bike from the tach cable end, and it hasn't reappeared while the bike has been sitting, and I've had the bike running on the center stand, too.

For the price of a few o-rings (mix and match, see which one fits best), a drive to the hardware store and back, and 5 minutes to install the o-ring...you might fix the leak.

 

Conversion to an electric tach is pretty simple; you just need to find a suitable tach, hook it up, and plug the tach-drive hole.

There is a tach plug for an '82 GS1000S Katana, p# 26442-45000, that will work perfectly.

 

good deal. I seem to have fixed my tach leak problem. I noticed it was loose, so I got a pliers and gently tightened it...no more dripping oil.

But if this comes up in the future again, I may look into converting to an electric tach.

 

Thanks for the tip Floogle, I'll have to give that a shot.

 

Re: Leak from tachometer cable fitting on head of 81 Seca 55

Ok, I think I finally got this friggin leak fixed.

I've tried everything (see older posts) without success. It still leaked, no matter what. I wasn't willing to settle for even one drip a day...I don't want ANY oil on my garage floor from any of my machines. My garage might get mistaken for a Harley shop or something.

So here's the secret...referring to this diagram: http://xjbikes.com/modules/coppermine/a ... chgear.gif

The tach gear housing needs a FLAT rubber washer in between the housing body and the head. I don't know the exact size, but a cheap package of assorted flat rubber washers I bought at Harbor Freight had it, so it can't be all that oddball.

I tried using a bunch of different O-rings in that spot, but they all leaked to one degree or another. I figured that since the hole on the head was beveled somewhat, an O-ring would work great. Not. The flat rubber washer did the trick. It's a neoprene washer, so it should stand up to the oil pretty well.

I hope this helps somebody somewhere who has one hell of an annoying drip. :wink:

 

you mean between the flange of #3 and the head?

I fixed mine by taking it to the machine shop, machining the inside of #3 to fit a different type of seal (replaced #4), and it works great. It is the type of seal that you would see on a valve stem or something in a car...complete with a strong spring around it to squeeze the tach drive. That kept mine from leaking.

Good tip on the flat neoprene washer too.

 

Yep, that's where I put the flat rubber washer. Your idea sounds pretty slick, too. I tried a bunch of different O-rings in that #4 spot and nothing made much of a difference.

Now all I have to do is fix the rich running and it will be the most perfect bike on the planet. Or maybe just the most perfect bike in my garage. :wink:

 

yeah, and all I need to do is raise the floats a bit. It is hard to start when hot, and I noticed today that when I restart it hot if I add a bit of choke it starts right up....

So it is lean on hot re-start. Damn...I hate taking those carbs off.