Homemade Tachometer Part

tracer1966 · May 16, 2014

I fabbed a part for the bike this week, and wanted to pass along the idea in case anyone needs something similar.

The missing part was the threaded attachment on the RH engine cover for the tach cable to thread onto. A PO lost it and held things together, mostly, with wire. I mainly used a chop saw and lathe in my brother's machine shop, but a hacksaw and drill press would probably suffice. It started with a 5/8 fine thread bolt.

TwoManyXS1Bs · May 16, 2014

Well now, that's interesting! So that tach cable adapter thread is english, 5/8 - 18 ???

tracer1966 · May 16, 2014

It is indeed. 5/8 SAE. I assume the -18 is for fine thread.

I'm pretty sure an M16 fine thread would have been best, but the local ACE didn't go past M14.

So I tried the SAE fine thread drawers and lucked out with the 5/8.

As noted, it might be off a little, but if it works as well as 7/16 does for 11mm, I'll roll with it. :bike:

Thanks for noticing!

jayel · May 16, 2014

put it in with your hammer wrench twomany

TwoManyXS1Bs · May 16, 2014

jayel said:
put it in with your hammer wrench twomany

Uh, okay. Which end do I use ???

tracer1966 · May 17, 2014

Another great 650 Jedi shares his powers with us Padawans!

Clearly, much Force you used in making this Hammer/Wrench/Saber yours!

2 thoughts . . .

1. Leatherman has got nuthin on you.

2. I hope you're not a proctologist.

That thing looks like something from the Middle Ages. If it was made in the 1960s, or there abouts, that would be close enough for most kids today.

You are hereby dubbed . . .

Sir Wrenchalot!

OK, so there are more than 2 thoughts here. That's why I'm still a Padawan. :shrug:

TwoManyXS1Bs · May 18, 2014

Well, decided to go out there, and check the tach drive thread diameter and pitch just to be sure. The diameter measured at 0.625 (5/8"), but that's very close to 16mm (0.630). The thread pitch was very close to 18 TPI (1.41mm), but the pitch is actually 1.5mm (16.9 TPI).

So, it's really an M16 x 1.5. The difference to the 5/8 SAE is so close that you could probably get 2 to 3 turns before the threads start to bind, maybe more if the threads are sloppy. This is kinda like using #10-32 screws in an emergency for M5 x 0.8 screws.

Edit: Confirmation that it's really M16-1.5mm.

http://www.xs650.com/threads/on-the-road-again-at-40-the-bike-that-is.49360/page-44#post-548936

Homemade Tachometer Part

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