2000 X1 Lightning rear cylinder spark

[Wibuellx1]

I'm new to Buells and have been working on a X1 lightning. I was having a hard time getting it started when I did a spark test and notice no spark to the rear cylinder. It has the "racing" ecm and after going through the service manual I wasn't able to find the problem. In the mean time I ran the battery down so had to charge it to keep trying. After charging to 100%, I had spark! I then replaced the battery with a new one and after charging, the bike fired right up. The issue is, the battery needs to be at or near full charge or I lose spark in the rear cylinder. Is this normal for these bikes?

 

[Cooter]

No.

 

[pdksh]

Buells like a strong battery. I would check your ground connections.

 

[Wibuellx1]

So not normal but strong battery? Could there be a draw in the start circuit? What does strong mean? A battery at 80% should be enough to get the coils to make the plugs spark?

 

[user_deleted]

So not normal but strong battery? Could there be a draw in the start circuit? What does strong mean? A battery at 80% should be enough to get the coils to make the plugs spark?

i have run into this situation on numerous occasions. here's the simplest way i can explain it: as a dual fire coil ages it typically needs closer to 12volts DC to fire both plugs than when it was new. it does NOT know which cylinder plug it is firing nor does it care. a battery that is aging and at sub-par output will often times not supply the coil with sufficient voltage during the "crank-to-start" mode. aging spark plugs....slightly fouled plugs...plugs with way-too wide of an air-gap....aging plug wires will exacerbate the problem. having said that if the plug wires ohm test ok....and if the plugs are replaced with iridiums...and gapped correctly...and the battery is up to snuff....and the problem continues....the coil pack is headed to death-row. and there ya go.

 

[Wibuellx1]

For some reason I thought this bike fired one cylinder at a time. Being a new battery I'm leaning toward the coil pack.

 

[Cooter]

You're sort of right. It does fire one cylinder at a time, even though both plugs are firing on the same signal, at the same time. It's because one cylinder is on it's power stroke and the other cylinder is on it's exhaust stroke, known as 'waste spark' ignition.

Although a weak battery (especially while cranking) can cause the coil to not fire, it would never affect just one cylinder. Lunatic is totally right, it would have to be a secondary ignition/high tension problem which includes the plug, the plug wire, and it's connections.

Buell's do like a strong battery, not for ignition purposes but mostly for high amp cranking duties.

What is your CCA rating of the battery? What is the cranking voltage? A new 220CCA battery, coil, wires, and plugs could be cheap insurance. Cheap batteries can't be trusted.

 

[Outlaw]

Ha, every time.

 

[Wibuellx1]

Basically if I keep the bike inside in a conditioned space, it will fire right up. If I put it outside in the cold for a few hours, the rear cylinder has no spark, but the front does.

 

[Cooter]

You can keep asking the same question, but you'll keep getting the same answer.

 

[user_deleted]

Basically if I keep the bike inside in a conditioned space, it will fire right up. If I put it outside in the cold for a few hours, the rear cylinder has no spark, but the front does.

are you absolutely positive the rear cylinder is dead when cold from loss of spark....or...loss of compression? THE first tell-tale sign of heavy internal wear/burned exhaust valves on an air-cooled V-twin is loss of compression when the motor is cold.
simple to determine: just switch the plug wire leads on the coil then try to start when it's cold. if the rear cylinder now fires and the front cylinder is dead it's the coil. if the rear cylinder remains dead it is loss of compression. compression check and properly performed leak-down test will determine the source of the leak and why.
PS-if your response is "i can't do that because the plug wires aren't long enough" or something similarly idiotic then clearly you need to have a pro look at the bike.

 

[Outlaw]

Buy that man a cold one ^^^^