Bonneville America Forums Forums Technical Forums Performance Mods Carb tuning buy removing ignition wire - BAD!

I was reading a technical bulletin on the BMW Airhead site and I came across some ignition system info. According to this thread you can damage your coils and/or CDI by pulling one plug cap off at a time to balance your air screws. They say on electronic ignition bikes this can cause high voltage leaks which can cause coil and CDI damage. I'm wondering if the folks who like to use this method are potentially damaging their ignition system. The BMW sight said this method was fine for points and condensor systems but not to use it for bikes with CDI modules.

Despite the well-intended advice seen on these forums, I never disconnect spark wires on electronic systems (including cars). It's especially risky given the cost of Triumph electrics.

If you ground the removed cap to the frame you mitigate the risk of damage.

Would it work to pull the plug/connect it to the cap/ground it to the head?

Magnecore plug wire company offers the same guidance in writing with regard to damaging a control module when an isolated circuit occurs via the fire signal having no where to go. I wouldn't be surprised if the same guidance applies to both bikes & cars.

I expect many have done so without dire consequence, but with my luck with motorcycle electrical stuff, I'd be the guy with the steaming circuit board juice dripping outta the control module.

Seems easy enough to keep a spare plug handy, and clamp it solidly to a ground while setting the idle. That way one could leave the working plug in the engine. That's one less steel into aluminum torque cycle as well, and you know we like that. To each his own.

Great idea Martin!

done that a couple time, that will make your O ring pucker!

This is what I've been saying all along. The only thing gained by disconnecting the ignition on one cylinder is a guarantee that the engine will stall if you get the mixture too lean. This means you will have to richen it before restarting and have to start adjusting all over. There is also the minor problem of the exhaust system on the dead side filling up with fuel and maybe exploding or spewing out flames when you reconnect the spark.
All you do is disconnect the balance line between the manifolds if you have one and block the vacuum ports. Adjust one mixture screw for fastest idle, readjusting the idle speed as needed to keep the engine running on just the idle port. Repeat on the other side. then set the idle speed to 1000 +/- 100 and go back and do it again to get a finer adjustment.
A V8 with a 2 bbl carb is exactly the same thing except the carbs are cast into one piece. Did you ever see a mechanic disconnect 4 sparkplugs to adjust the idle mixture on a V8?