My 'problem' was solved today. I called the Honda dealer's service department and he stated that both the '06 VLX and '06 750 Spirit run dual coil single fire ignition systems. He was familiar with the Cobra tach and said it will work fine on a VLX.
Now that I'm sure, I'll need to save up a few more dollars and voila... I'll know what rpms I'm running.
To give you an idea of a dual coil dual fire ignition, my Rebel with it's parallel twin engine has two coils and one spark plug per cylinder. It fires both coils and plugs at the same time. The one that is firing in the dead cylinder (not on the compression stroke) is considered 'wasted spark'.
The VLX has one coil and two spark plugs per cylinder. It only fires the coil and two plugs in the cylinder that's on it's compression stroke. The other coil and plugs do not fire on the dead cylinder. Dual coil single fire.
Firehawk,
it was great to hear that you figured out which tach will work on your Bike,
its nice to know, isn't it. I knew, that no matter what you call your ignition system that it would would work with a any Tach that works on the 750 Carb bikes.
Now that we seem to know that your VLX600 has a Dual Coil, Single Fire ignition the questions is what do *I* have for an ignition, what is MINE?
The reason i figured I have a single-fire and you must have Dual-fire is because I had installed one of those inexpensive Tachs on my bike and it read exactly 1/2 the RPM's the engine was doing, this tach was designated for any of the shadow 750's that had Dual-Fire ignitions.
So that tach got a 1/2 rpm reading on my bike and I sold it on ebay
to someone with a Carb Bike.
Cobra didn't list a Tach choice for the 2011 Aero (my bike) only the 2004-2009 Aero's. I bought one of these Tachs and it also got 1/2 RPM reading.
I returned it got my money back.
Finally I noticed Cobra sold a Tach for the 2011 Phantom and by then i knew enough to know that the engines and ignition systems are the same.
Cobra suddenly had a specific Tach model number for the 2011+ Phantoms
that departed from the model they offered for 2004-2009 shadows.
I bought the Tach specified for the 2011 Phantom and it read the RPMS correctly and worked perfectly, its on my bike today.
Knowing that Tachs get their readings from the "Pulses" of the Coil and the fact that i was getting 1/2 readings from the Tachs designated for the CARB
year bikes, I figured it was because the older bike had a Dual-Fire ignitions
"wasted spark" and that the Tachs for those bikes were designed to cut the "Pulse" count in half, in order to give a correct reading on a dual-fire bike.
Plus i figured that no-way would honda have gone from a Single-Fire ignition on the Carb bikes TO a Dual fire wasted spark on the new EFI Bikes.
So if you have Dual-Coil Single Fire what do I have?????
You'll love the Coba Tach, they're nice. the one thing i don't like is the guage light is a bit bright at night, but thats if i nit-pick.
Congrats Man glad you figured it out!
