Electronic tach conversion?

[eil]

The tachometer on my new-to-me GS750E doesn't work. Over in the project thread, I found that the reason for this is that the drive gear on the exhaust cam is stripped. I had resigned myself to purchasing a new exhaust cam. Or perhaps both intake and exhaust, they're pretty plentiful on eBay it seems. Not the end of the world, but more work and variables than I'm really interested in right now.

Then came this suggestion:

And get rid of the tach drive gears completely. The trick? Get a GS1150 or 550 electronic tach. Swap the faces with your 750and add a few wires and you have an electronic tach without the cable hassle. And just plug the hole in the old drive fitting.

Is it really as simple as all that? An electronic tach is totally the way I want to go, if possible. Can someone list me some years that would work for this conversion? I tried Googling and eBaying but only came up with a handful of questionable results. I looked at electronic tachs for other bikes too, but I'm worried about the tach innards not matching up with the GS750E dial face.

Thanks for any advice.

[koolaid_kid]

Yes, it is that simple. You need 3 wires; 1 for 12V power, 1 for ground, 1 for the signal from the coil. Not sure which ones would match up for your particular bike.

[Pete's GS]

And just how do you "plug the hole in the old drive fitting"? If it's not a tight fitting cap of some sort it's going to leak oil down the front of the motor, seems to me.

[rustybronco]

http://www.thegsresources.com/_forum/showpost.php?p=1920881&postcount=4

[eil]

Minor progress on this: I've found an electronic tach and verified that it matches the face of the mechanical tach. All that's left to do is see if I need to fab/mod the gauge housing in order to mount it (but maybe I'll get really lucky and won't have to?) and then hook it up. Details over in my "project" thread: http://www.thegsresources.com/_forum...hp?t=215295#38

For plugging the tach drive sleeve, I was going to just pull the gear and inner seal, and then fill it with JB Weld. (Leaving the outer seal alone... the sleeve will still be removable, so the option is always there to go back to a mechanical tach.)

[Griffyn]

I am definitely following this project, I've never liked the inaccuracy of a cable tach. The old '67 Sting Ray I'd occasionally get to drive in college was definitely a learning experience after the Porsche and the Celica GT with their electronic tachs.

That list of factory plugs is just the ticket, the guys who designed the engine know best how to make it work properly. Better than JB Weld anyway, especially in an environment with temperature extremes. And it'll look cleaner too, nothing worse than a beautiful bike with a slightly botched DIY fix.

[Pete's GS]

http://www.thegsresources.com/_forum...81&postcount=4

Freaking brilliant. Thank you! As for JB Weld, it's really not for motorcycles!

[eil]

If my existing sleeve was broken, I'd have no problem buying a plug, but I don't like paying for something I don't really have to when a DIY solution will work just as well. (And will probably teach me something in the process, which is even more valuable in my opinion.)

The tach drive sleeve is hidden up in an area where it will not be seen by most. If I decide to make it pretty, it will be a simple matter to paint it.

I haven't used JB Weld yet myself, but my understanding is that it's perfect for this application. Apparently once hardened, it can be sanded, filed, tapped, painted, and holds up to heat just fine. For an example of its versatility, see some of the more recent posts in Mr nvr2old's amazing CB400F rebuild: http://www.thegsresources.com/_forum...d.php?t=211474

[Griffyn]

Very familiar with JB Weld, and it works great for many applications. I have it sealing up a crack in the water pump of my VW, 3 years later and no problems.

But as a mechanic, a factory solution (especially one under $20) is always the best way to go.