lost spark 1and 2

[Eastcoaster]

Out for a great ride tonight 79XS I dropped spark to 1 and 2 not intermittent no spark at all
Barely Limped home. I am lost when it comes to electrical I don't know where to begin It is both 1 and 2 with no spark.

[CatatonicBug]

Are you sure it's a lack of spark, or just a lack of combustion? The coils cross over - 1&3, 2&4. Usually, if adjacent cylinders stop together, it's a fuel delivery issue.

[Eastcoaster]

Pulled the plugs no spark on 1 and 2

[Eastcoaster]

I first thought fuel also I thought fuel line clogged or kinked but pulled the plugs and no spark on 1 and 2?

[MPittma100]

Sparky has left the building

First thing to try is remove the spark plug caps on 1&2 plug wires. Cut about 1/4 inch off of each wire until you see fresh wire. Reinstall the caps and see if that puts you where you want to be.

I am assuming that you have stock coils. If you have aftermarket coils such as Dyna Coils, check the plug wire connection at he coil terminals.

Mike

[Eastcoaster]

Accell 8.8 aftermarket fairly new

[TopCatGr58]

Hey there,

Well, first of all, Bug brainfarted! Plugs 1-4 are linked, and 2-3 are linked via the coils. 1-2 & 3-4 are carb linked.

Next, you say you pulled the plugs....did you put the plugs against the head to ensure a complete circuit from it's paired plug thru the engine. If you just held the plug UP with it connected to the wire but was not against the engine, then you won't see a spark because the complete circuit is broken.

Next, you say it's the 79XS....I can only assume that you have OEM coils and also the Ballast resistor. It's rare but when you loose power to 1 of the 2 coils/plugs on a paired coil, it's usually due to too low of voltage to the coil. There's enough juice to fire the Primary plug, but not enough to get thru the engine and back UP thru the other plug and back to the coil for the complete wasted spark circuit.

So...either the Ballast resistor is building too much resistance lowering the voltage too low....or you're losing magic smoke somewhere so that 12 volts isn't getting to the Ballast resistor??

Run the bike/engine until it acts up again, then pull the connector for the BR and test it's resistance, shouldn't be much over 1.5 ohms...if much higher then it's dying/dead=replace. IF it's within spec, measure the voltage at the BR connector/harness side..should be 12 volts...if not, then need to trace back towards the TCI to see where it's loosing magic smoke!

T.C.

[cajun31]

Hey East

You stated Accel 8.8 which I believe is referencing your spark plug wires. To confirm what coils do you have? Is the Ballast resistor still in play or bypassed?

[Eastcoaster]

Thanks TC I am in bad shape when it comes to ignition I did pull all plugs against the head.
1 and 3 are dead 3 and 4 have spark. The bike will barely run so I am guessing ballast resistor is next to check? The coils are aftermarket Accell8.8

I am lost on this one is there one ballast resister for both 1 and 2 coils? I don't know what they look like. I have a meter but I am not much good past checking volts and continuity checks.

[Eastcoaster]

just pulled the tank Accell coils and checked again 1 and 2 dead 3 and 4 work

[Eastcoaster]

how can linked coils 1 and 4 and 2 and 3 have one that will not fire and one will on the same coil?

[TopCatGr58]

Okay, are the Accel coils 3 ohm style or 1.5 ohm style? Did you put them on, or were they already there?

IF they are 3 ohm style....you can determine just by removing the primary wires...and then measuring thru the + and - connectors.....if 3 ohms...vs. 1.5 should be fairly obvious to see. IF 3 ohms...AND you are still running the Ballast resistor....well there's your problem. The newer 3 ohm coils do NOT need the B.R., and you can simply bypass it. IT's a little metal doodad mounted just under the left side of the gastank/frame area. I'll grab a photo from the tech tips in a moment to add to this to show you what it looks like and where it is. Just unplug it from the harness, and either make a jumper or just cut/strip the harness side wires and connect together to bypass.



The B.R. is just below the tank rubber mount on the frame, that little silver flat thing on the frame!

T.C.

[TopCatGr58]

how can linked coils 1 and 4 and 2 and 3 have one that will not fire and one will on the same coil?

Re-read my earlier post....LOW VOLTAGE....takes a certain amount of KV to make a spark jump an air gap....low voltage generates less KV's and so the wasted spark coil generates enough juice to go thru the primary coil wire....the path the spark takes is thru one wire, thru the plug, then engine, then back up thru the other plug and back to the coil....it's a LOOP! SO...not enough KV to jump the second gap!

T.C.

[CatatonicBug]

Hey there,

Well, first of all, Bug brainfarted! Plugs 1-4 are linked, and 2-3 are linked via the coils. 1-2 & 3-4 are carb linked.

Oops! Sorry 'bout that. That's what happens when I stay away from this site for too long....

[Eastcoaster]

We are getting close Yes the Ballast resister is there! The coils were on the before I had it bike it ran well before I can try the test to see if 1.5 Could this resister be bad?
Looks like 2 red wire plug in part
Thanks TC learned a lot already I was way off track