Topic: Feedback on PAMCO ignition system

[Kustomizer]

So my Cb750 project that I just finished has developed a starting/running problem.  Generally, it has low power and runs for a couple of minutes and then when I take it for a ride it feels like it's starving for gas, then it dies and I have a very difficult time getting it started.  Carbs were rebuilt and rejetted. So, being the newbie to Honda CB750's I figured I better run through and give this a tune-up even though it ran great last fall when I started the project.  I thought about updating to a PAMCO ignition system.  What are your thoughts on it?  Is there a link to tune-up info or will my Haynes manual have everything I need(haven't had a chance to look at it yet).  I need to get this thing running so I can put a few miles on it before I store it for winter.

[70CB750]

Check the tank ventilation too.

Pamco information is here:

http://www.cb750ignition.com/

And Pamcopete is a member too, very helpful.

I had Pamco in Dorothy for 4 years and 25 000 miles with 0 problems.  I also out Pamco in the K3F Red I finished rebuilding recently, Pamco is great.

[flybox1]

who did your carb rebuild/rejet, and why was it re-jetted?
if the work wasnt done by you, the work itself is suspect (very few shops work on OLD bike, or even know how)
if it was rejetted (without major changes to the intake and exhaust config from stock setting) the re-jetting is suspect.
How was the jetting tested to be correct? Exh gas analysis or seat-o-yer pants test?
aftermarket jets are know to cause all sorts of tuning issues.  what brand jets were used?

havent even mentioned any of the 3000mi periodic maintenance items necessary for a properly tuned and running bike 

too many things going on here to jump to the conclusion an electronic ignition is needed. sorry

Heard nothing but good things about PAMCO ignitions.....

[Kustomizer]

who did your carb rebuild/rejet, and why was it re-jetted?
if the work wasnt done by you, the work itself is suspect (very few shops work on OLD bike, or even know how)
if it was rejetted (without major changes to the intake and exhaust config from stock setting) the re-jetting is suspect.
How was the jetting tested to be correct? Exh gas analysis or seat-o-yer pants test?
aftermarket jets are know to cause all sorts of tuning issues.  what brand jets were used?

havent even mentioned any of the 3000mi periodic maintenance items necessary for a properly tuned and running bike 

too many things going on here to jump to the conclusion an electronic ignition is needed. sorry

Heard nothing but good things about PAMCO ignitions.....

The carbs were rebuilt by my friend's son who spent the summer rebuilding carbs for Ken at CycleX.  They were rejetted because I upgraded the exhaust to a 4 into 1 and  running pods.  I agree, that there is no info on the 3000 mile maintenance because I haven't done it yet, and I should have made it clearer when I posted, but I plan on doing that now, which is why I asked for the info.  The question on the ignition really wasn't meant as a solution to my problem, but more of an upgrade when I get things running right.  I've heard alot of bad things about running points on these bikes and thought I'd start researching.  Being new to Honda and still learning I'm relying on others for some stuff (doing work I normally would be doing) and to be right and I hope to remedy that as time goes with info from all of you and to start gathering trusted resources to help.

[flybox1]

I dont think the PAMCO is really an upgrade.  Its just different. 
I have had no issues running points on either of my CB's.  If its in tune, does it really need an 'upgrade'?
I mean...HONDA thought points were good enough after all the $$$ and R&D. right?!

First things....3000mi maint items.  Get that done...and when you get your bike running properly, IIWM, why not spend the 'upgrade" $ on the stuff that's going to help save your @$$...like brake/suspension improvements, tires, swing arm bushings, etc., or better riding gear 

Dont get me wrong.  I've got nothing against electronic ignitions. 
I just think if you've done your bike right, its not necessary.

[Kustomizer]

I dont think the PAMCO is really an upgrade.  Its just different. 
I have had no issues running points on either of my CB's.  If its in tune, does it really need an 'upgrade'?
I mean...HONDA thought points were good enough after all the $$$ and R&D. right?!

First things....3000mi maint items.  Get that done...and when you get your bike running properly, IIWM, why not spend the 'upgrade" $ on the stuff that's going to help save your @$$...like brake/suspension improvements, tires, swing arm bushings, etc., or better riding gear 

Dont get me wrong.  I've got nothing against electronic ignitions. 
I just think if you've done your bike right, its not necessary.

Good info, thanks!

[Scott S]

 The Pamco is great, but it sounds like you're having other issues. It's not a cure-all, but it is a good product with excellent customer service.
 The Pamco won't cure a carb problem or fuel delivery problem, though.

[CycleRanger]

Have you replaced the plug caps/points/condensers/ ohmed the coils/ checked the battery and charging system?  Have you done anything to the electrical system like added different lights?
And I assume a carb sync was done when the carbs were refitted.

[Kustomizer]

Have you replaced the plug caps/points/condensers/ ohmed the coils/ checked the battery and charging system?  Have you done anything to the electrical system like added different lights?
And I assume a carb sync was done when the carbs were refitted.

All on the list will be getting changed or checked.  The battery is new and I haven't checked the charging system.  There are new turn signals.  What should good coils on my k6 ohm out to?

[flybox1]

Have you replaced the plug caps/points/condensers/ ohmed the coils/ checked the battery and charging system?  Have you done anything to the electrical system like added different lights?
And I assume a carb sync was done when the carbs were refitted.

All on the list will be getting changed or checked.  The battery is new and I haven't checked the charging system.  There are new turn signals.  What should good coils on my k6 ohm out to?

http://www.hondachopper.com/garage/troubleshooting_charging_system/troubleshooting_charging_system.pdf

[madmtnmotors]

What year? The 77/78 have a fuel filter inside the fuel tank. Some earlier models have a filter screen in the petcock.


Have you checked the fuel filter?

[Kustomizer]

Have you replaced the plug caps/points/condensers/ ohmed the coils/ checked the battery and charging system?  Have you done anything to the electrical system like added different lights?
And I assume a carb sync was done when the carbs were refitted.

All on the list will be getting changed or checked.  The battery is new and I haven't checked the charging system.  There are new turn signals.  What should good coils on my k6 ohm out to?

http://www.hondachopper.com/garage/troubleshooting_charging_system/troubleshooting_charging_system.pdf

Thanks, I'll check it out.

[Kustomizer]

What year? The 77/78 have a fuel filter inside the fuel tank. Some earlier models have a filter screen in the petcock.


Have you checked the fuel filter?

1976. No inline filter, but new tank screen/filter.

[PeWe]

There are several posts about ignition and coils that is a good idea to replace with ignition.
Points, Pamco or Dyna-S, all need a good working advancer unit that advance to full advance at correct rpm. Not before 2500rpm. Sloppy adv springs have threads too about shorten them 1/2 wound.

The problem here can be fuel flow to carbs. Hose can be blocked or the menitioned petcock with its filter.

[Kustomizer]

The tank was just sealed.  I'll add the other things to my list of things to do or check.  Thanks for all the info so far.

[dusterdude]

So my Cb750 project that I just finished has developed a starting/running problem.  Generally, it has low power and runs for a couple of minutes and then when I take it for a ride it feels like it's starving for gas, then it dies and I have a very difficult time getting it started.  Carbs were rebuilt and rejetted. So, being the newbie to Honda CB750's I figured I better run through and give this a tune-up even though it ran great last fall when I started the project.  I thought about updating to a PAMCO ignition system.  What are your thoughts on it?  Is there a link to tune-up info or will my Haynes manual have everything I need(haven't had a chance to look at it yet).  I need to get this thing running so I can put a few miles on it before I store it for winter.

Love it

[Airborne 82nd]

Sounds like from your questions you need to download the factory Honda service manual from this site. It has all the tuneup info. But It will not help with the pods others here will.

[HondaMan]

The symptoms do sound like a fuel restriction problem of some kind (or tank vent plugged, like someone said above).
Points: they are uber-reliable. They do require a little maintenance now and then, but one set can last for 40,000 miles if you take care of them (mine did!). Add a Transistor Ignition to them, and they may go even longer than that.

Most people who don't like points also don't know how to use them, IHMO...

The coils: if you have the OEM coils for a K6, the primary side will be 4.4 to 4.5 ohms. If they happened to receive a set of F0 coils (as some bikes then did), they will be 4.3 to 4.5 ohms instead. If they are more than that, they are having issues...

If the coils are NOT Honda's own, it might be a little harder to define the ohms value of the primary side (and if they are less than 3.0 ohms, they won't work with these bikes). Last summer I 'repaired' a 750 that had received 2.5 ohm (CDI system) coils from a website that sold them as "CB750 coils, fits all models", because they had 100mm center-to-center mounting holes. This burned the bullet connectors and kept his battery low all the time: he had to put it on a battery charger every night, just to ride it to work and back.

[Kustomizer]

Thanks Hondaman and Airborne!

[pamcopete]

When looking at the resistance of a coil and its effect on the battery and charging system, you have to take into consideration the effect of the dwell angle because the effective current draw is the average current with the engine running and the coil is not on all the time. In the case of points, the coil is only drawing current when the points are closed. In the case of an electronic ignition, the coil is only drawing current when the driving transistor is on. The time in degrees that the coil is drawing current is called the dwell angle.

Starting with a stock coil and points with a 5 Ohms primary resistance and a dwell angle of 185 degrees, it  goes like this.

Current when the points are closed: 13.5 Volts/ 5 Ohms = 2.7 Amps. The coil is on for 185/360 degrees = 51% of the time. So, the average current draw is 2.7 A X .51 = 1.37 Amps. There are two coils, so the total average current draw is 2 X 1.37 = 2.75 Amps.

An electronic ignition with a 120 degree dwell angle, such as the PAMCO, with a 2.5 Ohm coil will draw a peak current of: 12.5 Volts / 2.5 Ohms= 5 Amps. The dwell angle of 120 degrees means that the coil will be on for 120 / 360 = 33% of the time. So, the average current draw would be 5 X .33 = 1.66 Amps. There are two coils, so the total average current draw would be 1.66 X 2 = 3.32 Amps which is 3.32 - 2.75 = 0.57 Amps more than points with a 5 Ohm coil, which is roughly equal to the two bulbs that light up your speedo and tach.

Notes: 1. I use 12.5 Volts for the electronic ignition because the driver transistor drops 1 Volt.
            2. The electronics in the electronic ignition uses .020 Amps.

[Kustomizer]

When looking at the resistance of a coil and its effect on the battery and charging system, you have to take into consideration the effect of the dwell angle because the effective current draw is the average current with the engine running and the coil is not on all the time. In the case of points, the coil is only drawing current when the points are closed. In the case of an electronic ignition, the coil is only drawing current when the driving transistor is on. The time in degrees that the coil is drawing current is called the dwell angle.

Starting with a stock coil and points with a 5 Ohms primary resistance and a dwell angle of 185 degrees, it  goes like this.

Current when the points are closed: 13.5 Volts/ 5 Ohms = 2.7 Amps. The coil is on for 185/360 degrees = 51% of the time. So, the average current draw is 2.7 A X .51 = 1.37 Amps. There are two coils, so the total average current draw is 2 X 1.37 = 2.75 Amps.

An electronic ignition with a 120 degree dwell angle, such as the PAMCO, with a 2.5 Ohm coil will draw an average current of: 12.5 Volts / 2.5 Ohms= 5 Amps. The dwell angle of 120 degrees means that the coil will be on for 120 / 360 = 33% of the time. So, the average current draw would be 5 X .33 = 1.66 Amps. There are two coils, so the total average current draw would be 1.66 X 2 = 3.32 Amps which is 3.32 - 2.75 = 0.57 Amps more than points with a 5 Ohm coil, which is roughly equal to the two bulbs that light up your speedo and tach.

Notes: 1. I use 12.5 Volts for the electronic ignition because the driver transistor drops 1 Volt.
            2. The electronics in the electronic ignition uses .020 Amps.

Thanks Pamcopete!