Shift light

[Clay Pitkin]

Does anybody know if there is a shift light available for a 3 cylinder engine? Or if one can be modified to fit a 3 cylinder?

TIA
Clay

[Milwaukee Midget]

Let me make the assumption that the shift light relay is a component of the tach.

If that's the case, I would check around for a speedometer repair shop.  A lot of these folks do gauge repair, and if you let them know what you need it to do, it's probably just a matter of replacing a couple of components to recalibrate it.

One other thought - electronic devices and circuit boards have become increasingly difficult to work on, and it is due in large part to smaller components and newer, cheaper production techniques.  If you intend to modify a tach with a shift light, get yourself an older one - it will be a lot easier to work on, and a lot more forgiving if you take a soldering iron to it.

Of course, you could use a 6-cylinder tach and multiply by 2.  Or a 4-cylinder tach and multiply by 1.33.

[willieworld]

clay   i have a dynatek shift light on my bike and my wife sherris bike --you dont need a tach --they make one for a 2 cylinder and a 4 cylinder --sherries bike is a single cylinder --i just cut an extra window in the timing wheel so that it would fire on the exhaust stroke and tricked the system into thinking it was a 2 cylinder --any way there web site is   www.dynaonline.com        a great product   willie buchta

[38Chevy454]

Of course, you could use a 6-cylinder tach and multiply by 2.  Or a 4-cylinder tach and multiply by 1.33.

My thought exactly, the shift light has no clue what the number of cylinders are, it just counts the number of firing impulses.  So for example, on a 4 cyl model, if you want 6000 rpm shift point, use a 8000 rpm module (MSD plug in type) or setting on 4 cyl mode.  That would be equal to 6000 rpm on 3 cyl.  Or use a 6 cyl shift light and use a 4000 rpm module or setting which would equal a 8000 rpm on 3 cyl.  Just choose what you need and factor the module or setting appropriately.  My examples use easy claculations, but you could get it to what you want exactly.

[willieworld]

with sherris bike  a 1 cylinder motor the shift light would have been set to 1/2 the rpm she wanted to shift --only problem lowest setting on the shift light was 4000 rpm when the light came on she would have been at 8000 --cutting the extra window worked --i know that they make a 2 cyl and a 4 cyl  but the lowest setting is 4000 rpm   thanks  willie

[MCR]

If it's a distributor 4-stroke engine, you will just use any light that says 4-6-8 on it, set it to 6, and dial it to half the target RPM.  So if you want 8000, set to 4000. 

If it has a "dead spark"; a distributor that runs at crank RPM, just set the shift point normal for the 6-cyl.

If it is "one coil per cyl", you might need a newer light that has a One Cyl and Two Cylinder setting.  Hook to one coil 12v lead.  If it has one spark per two revs (normal) set to 1 cylinder.  If it has a dead spark, set to 2 cylinder.

For two stroke triples, there are both a distributor model and a 3 coil model.  You will use 2 cylinder setting for the 3-coil version, and you will use the 6 cyl setting for the distributor model.

Clear as mud?

[38Chevy454]

with sherris bike  a 1 cylinder motor the shift light would have been set to 1/2 the rpm she wanted to shift --only problem lowest setting on the shift light was 4000 rpm when the light came on she would have been at 8000 --cutting the extra window worked --i know that they make a 2 cyl and a 4 cyl  but the lowest setting is 4000 rpm   thanks  willie

Willie, you are correct in that you in effect tricked the ignition system into thinking it was a two cylinder.  That was a good idea.  You are doing exactly what MCR is stating below.  You created the dead spark situation.

If it has a "dead spark"; a distributor that runs at crank RPM, just set the shift point normal for the 6-cyl.

If it is "one coil per cyl", you might need a newer light that has a One Cyl and Two Cylinder setting.  Hook to one coil 12v lead.  If it has one spark per two revs (normal) set to 1 cylinder.  If it has a dead spark, set to 2 cylinder.

[sheribuchta]

the harley dist. turns 1/2 engine speed and fires both plugs every revolution --one plug is fireing on the exhaust stroke -- willie buchta

the funny part --i called the mfg. they told me i couldnt do that --maybe the janitor answered the phone-LOL

one time i built a harley motor--it had fuel inj. -i took it off an put a carb on --i didnt change the timing wheel which had 6 windows 2 for spark and 4 for the injectors--it was really funny when i started the motor    LOL