Topic: Honda Man ign. and static timing question

[Toxic]

I have HondaMan's ign. box with my stock points and as I was setting up to do my static timing, I couldn't get the light bulb to illuminate.

With one end of a light bulb attached to a solid ground and the other attached to the live wire on the points the bulb should light up.  I tried using a circuit tester, one with the light built into the handle and it wouldn't light up either.

So I checked and I have spark on the number 4 and 3 cyl so I know the points are working as are the coils.

The HondaMan instructions are very well written and easy to follow so I'm sure I have it hooked up right.

When I replace a 12volt bulb with an led, sure enough it illuminates.

So my question is why the led works and not a 12 bulb?

I believe the HondaMan unit is designed to reduce the load on the points so they last longer and need less periodic adjustment.  Don't quote me on that but something to that effect.

The voltage at the points is 11 volts, the battery is fully charged at 14.5V.

This is on my 76 CB750K



If this is normal with a HondaMan unit installed I will just go ahead and use the led buld to set my static timing.

Thanks in advance

[bollingball]

Toxic: I would PM or email Hondaman. He could walk you through it faster than any one. I would like to know the answer. Getting ready to get the unit.

 Wait I have his book I will see if it says any thing about it and get back in a little bit.
   
           Ken

[bollingball]

Toxic: From what I read it does drop the voltage at the points. That is why the points last longer.So led makes sense or use a ohm meter. Glad you posted this will help me and others I'm sure

Maybe HondaMan will see this in case I'm wrong.

          Ken

[HondaMan]

I'll post the answer here so everyone else can see it, too. 

The Ignition has a 100 ohm resistor inside to limit the electrical current to the points. This means that only a small incandescent lamp would light if doing static timing (like maybe one of the instrument lamps), so don't use a big light bulb to do static timing with this gizmo. An LED would work OK, too. For example, if a 3 watt bulb (like the NEUTRAL bulb or the HIGH beam bulb) is used, it will light up about 'halfway' bright. But, if a #1035 or similar turn signal bulb is used (15+ watts) then it won't even make the filament glow.

This current-limiting resistor is the key to making the points last so long, but it does have some limitations when you are doing static timing. And, when the points are open and you hook up a high-resistance voltmeter to it, the meter will show 12 volts because no current is flowing. If you then leave the meter connected and jumper in that light bulb, you will see the voltage drop in proportion to the current being drawn by the bulb: small wattage bulbs drop it less than higher-wattage bulbs. In the "total sum" of the amount of power involved, it 'acts' like the power to the points is about 6 volts at 0.1 amp, which lets them live forever.

At one time (3 years ago) I designed a 'built-in LED timing light' for this Ignition, but the LEDs that were available then were simply not bright enough at 1500+ RPM to make the thing work reliably. Today the LEDs are getting better, and next winter I'll be revisiting this add-on device to see if it is viable, which will make timing setup and checking so much easier.

[Toxic]

Thanks for that explanation.   I will use the led shown in my pic to set the static timing

[Brantley]

A little off topic but I gotta give you props on using allen screws on your points adjusters. Great idea- I'm totally doing that next tune up time. The washer behind looks plastic? Optical delusion or... what gives?

[Toxic]

Washers are metal, the flash makes them look shiney.

The allen head screws help with the fine adjustments.

After much fine tuning, both the 2-3 points and the 1-4 points start to open and illuminate the led at the "F" mark