Topic: Ignition / Coils for a 350

[pegula]

First of all, how "big" should the spark be? When I check the spark on 1 and 4 seems consistent but also pretty small. On 2 and 3 it seems extremely inconsistent. I checked the points and they seem ok but I am by no means an expert. I don't see any problems with the leads going to the plugs and the pugs are brand new. Can I switch the coils to see if that's the problem?

I'm thinking maybe I'll just try to avoid future headaches and get an electronic ignition and new coils. Does anyone have a recommendation for the two and maybe where to get them? The Dyna S seems to be popular but which one (ohms) is the way to go?

Thanls for all the help!

[TwoTired]

First of all, how "big" should the spark be?

Big enough to jump from one electrode to the other.  What is your spark gap measurement?

Can I switch the coils to see if that's the problem?

Well... yeah, but... What problem?

[petersan]

you should be able to switch the coils to diagnose the inconsistant spark issue.  If it's not the coils - it may be that the points are in need of cleaning and re-gapping, or need new condensors.


As far as I understand (from what I remember - conglomeration of this site and Dyna's site):

If you are keeping stock points - you should use 5 ohm coils (if you replaced with Dyna - or some others)

If you switch out points for Dyna-S ignition - you can use either 5 or 3 ohm coils, 3 ohm coils will give you a stronger spark and is fine to use with standard plugs for the bike.

I'm plenty happy with my dyna components - got the dyna-S first (used with stock coils) and upgraded to 3 ohm coils a year later.

[pegula]

The problem that there is basically no spark on 2 and 3. The pipes almost always stay cool.

It seems odd because occasionally (twice) the bike will run strong on all 4 cylinders but that's rare.

When I picked it up about 2 weeks ago it ran great for the 20 mile ride home but since then, not so much.

Thanks!
Matthew

[TwoTired]

Do go check out your points, then, for sure.

The contacts can become pitted and carboned up from arcing.
 The worst senario is if the engine crankshaft is rotationally positioned to where the points are only just making contact, and the ignition is turned on.  The low resistance contact heats the point surfaces, and they burn and form a carbon insulator.  For this reason, you should not leave your ignition switch on without the engine running (or turn the Off-Run-Off switch to Off, which shuts off power to the coils/points).

The coils cannot do their job properly without good points, adjusted correctly.
Do you have a manual to explain how this is done?

Cheers,

[pegula]

D'oh

Looks like I was barking up the wrong tree. Just took it outside and I am getting a consistent spark on 2 and 3. I guess it's onto verifying that the carbs are getting fuel? Could just those two have gotten blocked somehow?

I had the carbs out and it wasn't real clear how the fuel was distributed to the carbs from where the tube comes in.

It's raining now so at least I'm not missing out on riding at the moment.

I do have a workshop manual but I have to go pick up a feeler gauge.