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Selecting the correct tacho for your bike


OK, you've seen plenty of people at race meetings with a Scitsu tacho, but how do you know which one to select for your bike?

First - don't panic !
It's pretty easy to do, read through this short guide. If you're still not sure, just give us a call on the number at the top of the page, or send an e-mail and we'll work out what you need.

Next, decide what you want the maximum revs to be on the dial. You can have anything from 8,000 right up to 20,000 rpm . Just select the range in the options when you order your part.

The next part is the most critical. The tacho needs to be set-up by us for the correct sparks-per-rev that your engine produces.
We nominate a colour for each of the spark-per-rev possibilities :-
 

 
White 1 spark per 2 revs                   ( e.g. single 4 stroke )
Red 1 spark per rev                        ( e.g. single 2 stroke )
Blue 2 sparks per rev                      (e.g. 4 cylinder 4 stroke )
Green           3 sparks per rev                      (e.g. 3 cylinder 2 stroke )
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Orange 3 sparks per 2 revs                 (4 stroke triple)
Brown 1 spark per rev (uneven)         (Some V twins e.g 45 degree crank)
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Yellow 1 spark per 2 revs                  (Magneto 4 stroke single)
Black 1 spark per rev                      (Magneto 4 stroke twin)















The example engines types given above are typical of the type using a particular tacho. You must work out how many sparks your particular engine produces.

Here's an example:
4 Stroke
4 Cylinder 
2 Twin ignition coils, triggered from 2 pickups on crankshaft.
The crankshaft has 2 pickups, so it must be making the ignition fire twice every rev of the bike , so in this case a blue code would be selected.

Here's another example:
4 Stroke
1 Cylinder
1 ignition coils, triggered from 1 pickup on crankshaft.
The crankshaft has 1 pickup, so it must be making the ignition fire once every rev of the bike , so in this case a red code would be selected.

Last example:
4 Stroke
1 Cylinder
1 ignition coil, triggered from 1 pickup on the camshaft.
The camshaft has 1 pickup, so it must be making the ignition fire once every other rev of the bike , so in this case a white code would be selected.


On a V engine, where one head is well away from the other, you can work out how many sparks per rev is produced for one side only.

New BTH magneto's using an external coil should be treated as a standard ignition. Only use a magneto tacho for magnetos using points.

OK, once that's done, you're ready to order. Just select the colour code and revs from the drop down boxes on the tacho order page.