number of teeth on pinion and generator gears

[awander]

Counting teeth in the picture in the 1948-57 Svce Manual, it looks like the pinion has 21 teeth, while teh generator has 14,meaning the generator will turn 1.5 times as fast as the engine.

Can anyone confirm the tooth numbers?

[chuck 56 pan]

The generator does have 14 as you said.

[Panacea]

I'm wondering what the pinion to generator ratio would be, I'd guess the genny turns half as fast as the engine...

[58flh]

ANDY---You are correct -(21 on the pinion & 14 on the genny)---Richie

[1950Panhead]

the generator has 14,meaning the generator will turn 1.5 times as fast as the engine.

Timer=42t, Idler=51t, gen=14t
2500 crank rpm = 1250 timer rpm = 1029 Idler rpm = 3750 gen rpm.
Jerry

[awander]

Thanks, everybody!

next question-what are typical engine RPMs in use?

[kitabel]

1. in a gear train, only the first and last tooth counts matter, and their ratio remains constant regardless of the tooth count or number of intermediate gears
2. there isn't a set ratio (which is why a front mag is such a pain), it's just a good speed; slower kills the battery at low speed, faster wastes power
3. changing the generator ratio involves changing the generator gear, which means the idler must also change, and be re-located
4. between 500 and 5,000 RPM
5. why?

[awander]

1. in a gear train, only the first and last tooth counts matter, and their ratio remains constant regardless of the tooth count or number of intermediate gears
2. there isn't a set ratio (which is why a front mag is such a pain), it's just a good speed; slower kills the battery at low speed, faster wastes power
3. changing the generator ratio involves changing the generator gear, which means the idler must also change, and be re-located
4. between 500 and 5,000 RPM
5. why?

I'm not sure what your numbers refer to, but I'll use them as well:

1. Yup, that's why I only asked about the pinion and the generator gears.
2. What do you mean there isn't a set ratio, the ratio is 1.5:1
3. Who said anything about changing the ratio?
4. Are you taking about engine RPM? If so, that is not very helpful.
5. I am trying to do some work on documenting the actual output of a 3-brush generator, with the generator off of the bike, and so some typical cruising speeds are necessary, as well as the gear ratio.

[kitabel]

Ooppsss.
The last question I got on this subject was someone trying to reduce engine drag by slowing up the generator drive.
I meant they weren't looking for such an exact number, just a range of speeds, because the generator speed also varies with the sprocket sizes.
Cruising speed RPM? My guess: almost always above 2K, probably not faster than 3.5K.

[awander]

I just did someome quick calcs for my bike, with stock gearing except for a 25-tooth countershaft sprocket and slightly "less tall" than stock tires. They show that in 4th gear, I will be doing 50MPH at about 2300RPM and 70MPH at about 3200RPM.

Meaning generator speeds of between 3450-4800RPM.

[58flh]

Both of you are right on!--For a daily runner I have had RPMs ranging from 3 to 3500RPMs is a safe bet.---RICHIE