Topic: Cb550F intermittent spark failure

[trand]

Hi, 1975 Cb550F. Carbs all cleaned, balanced, synchronized, happy. Bike runs great for 30 miles, then cuts out on cylinders 1&4. With it running on 2&3, I can pull off 1&4 plug caps. No change, and no spark. After I let bike cool down, it will usually start right up and run beautifully on all four cylinders... then 1&4 stop firing again.

I have changed out the coil (twice!), examined all connections and checked the timing with a strobe. Plugs and wires are also new.

There is a Dyna S electronic ignition system installed. The testing procedures for this unit are beyond my level of understanding or equipment...

Why would it fail after a variable, but short length of time at working temperatures? Why the right side coil (cylinders 1&4) repeatedly fail? Why such a binary (on/off) ignition failure?

Please help!

[TwoTired]

Probably your electronic ignition is heat sensitive.  Seems to be a common problem with the Dyna-s with some manufacturing dates.

You might get it to run longer with the points cover off.  If Dyna won't fix or replace it, you have to buy another ignition trigger.

Cheers,

[Greyhound]

Wow interesting.

What is the date of manufacture on the Dyna S unit you have?

Are Charlie’s Place ignition systems more reliable after all?

[Greyhound]

Trand,

What type of coils are you using? Stock or Dynatek coils?

[HondaMan]

The Dyna trigger units, when they fail, often fail with heat, working OK when cold. If I had $1 for every time I have seen (or helped others find) this I could buy another 750...one way to test if yours is dying like this is: adjust the 1-4 trigger closer to the center (toward the advancer cam), or in other words, "reduce the gap" between the pickup and the advancer. If this just makes the timing change instead of dying altogether with heat, then it is dying, but not yet dead.

[Greyhound]

HondaMan,

Which type of coils would you recommend for a 550 in terms of reliability? Also, which type of electronic ignition unit?

I was about to install a Dynatek S ignition and 5ohm Dynatek coils... Is there anything more reliable/better?

(I don’t mean to hijack the thread, but perhaps your answer will help the op as well).

[HondaMan]

HondaMan,

Which type of coils would you recommend for a 550 in terms of reliability? Also, which type of electronic ignition unit?

I was about to install a Dynatek S ignition and 5ohm Dynatek coils... Is there anything more reliable/better?

(I don’t mean to hijack the thread, but perhaps your answer will help the op as well).

The Dyna 5 ohm coils are real good ones! The Dyna S ignition seems to be having less failures lately (new ones, anyway) than a few years ago, But the major question is: what bike do you have? Only the 750 in the SOHC4 lineup makes enough electrical power to run a Dyna S without much trouble (and then with OEM coils or 5-ohm coils for the most of them). The 500/550 cannot 'keep up' with the extra 1.5 amps of power it demands until around 4000 RPM, so anytime the engine runs below that the battery is losing ground. I get about 1-2 e-mails every week from those riders, asking how to 'fix' that: you can't. You must either ride with high RPM all the time and idle very little, or switch to points and/or use the Transistor Ignition that I created expressly for these bikes. It only uses 0.1 amp extra current, so even the 350F and CB/CL/SL350 twins can feed it.

[Mooshie]

+1 for Mark's (Hondaman) transistorized ignition.  Works flawlessly and any problems you can simply switch back to points.