Forum

[Rattlebattle]

I don't think it is the case that nobody can make an electronic tachometer for the Bullet. For one thing RE themselves fit one to the CGT, as well as an electronic speedo. The issue here seems to be a lack of clarity on behalf of the supplier as to whether it is actually suitable for a single cylinder bike and, if so, what connections need to be made. As far as I can see it should be wired the same as a non wasted spark twin ie like a Brit twin with two sets of contact breakers. The tachometer only needs to know when a cylinder fires and what this represents in terms of crank revolutions. It gets the former from the low tension side of a coil; the latter it will determine from the type of engine, via the connections made,unless it is switchable according to the number of cylinders, engine configuration and type (2 or 4 stroke). It's not rocket science, just poor instructions and/or product knowledge by the supplier.

[KenKZN]

Hi ChrisD, indeed I'm also in SA and visiting your area soon. I haven't been able to find your pics on photobucket. Perhaps you could text me on 0716832435. Regards, Ken

[ChrisD]

Sorry Ken (and others) I haven't yet photo'd the items - I'll do them now.
No answer yet from the manufacturer Compufire either.
ChrisD

[Thack]

Totally agree with Rattlebattle: OF COURSE somebody can make a suitable tacho. I remember many of the after-market tachos were configurable for a wide range of engine configurations, including 2/4 stroke, 1/2/4/6/8 cylinders, wasted spark/or not. It's the obvious solution: trivial electronically, and gives you a one-size-fits-all product.



I don't understand what the "single fire adapter" is for. It's obviously designed for a twin cylinder bike; presumably it monitors both cylinders and generates a tacho pulse when either fires? But why would this be recommended for a SINGLE cylinder bike? This is all very odd - in my experience a tacho only ever needs to monitor one cylinder.



I don't think the dual-spark system will help because the sparks occur simultaneously. Having said that, I can't believe it'll do any harm at all to connect both pickup wires to the same coil terminal. I think this will be electrically equivalent to using two separate coils anyway, so it doesn't seem worth messing about.



I'd be very tempted to seek clarification from the vendor. If you can't do that, just try connecting both pickup wires to the coil and see what happens. (It won't be anything bad, that's for sure).

[papasmurf]

An electronic tacho only picks up on one cylinder, so I am a bit puzzled as to what the problem is.

[Nico]

Hi Chris D,
you write
"So I connected both leads from the ‘single-fire adaptor’ onto my dual coil negative terminal so that, essentially, there were 2 input signals from the coil. To no avail as the tachy still records half revs. PaulMH, yes that’s what my dual coil does – one spark per 2 engine revs but I need 2 sparks hence my thought about two separate coils instead of my dual."

If I understand your description correctly, you will have 2 sparks doing it this way, but they occur at the same time. The sparks need to be spaced by 360° crank angle.

You can either
- use an electronic ignition with wasted spark as described by others
- or you can buy the correct rev counter (2:1 are unfortunately rare, most are 1:1)
- or an adjustable rev counter where you can type in the relevant ratio
the below link is unfortunately in German, but they can provide everything in decent quality
http://www.mmb-messtechnik.de/index.php ... zahlmesser

[Barry_Q]

It's a pity that I don't have a wiring diagram of the electronic tacho fitted (as standard) to my Lightning. However. If I remember correctly. It has one wire fitted either side of the coil (Trigger). Then there's the two wires that power the tacho. Lastly, there's the single wire that goes to the bulb. This doesn't help you much as you've got three wires. Logic would suggest that one wire goes to the contact breaker side of the coil (Trigger). One wire would be negative, the last being a switched Positive.