The Gunson Colortune tool

I have a Gunson Colortune 14mm unit on order, and am looking for some practical suggestions before attempting to use it. :silly:
This tool is supposed to be a foolproof means to getting carburetors precision-adjusted, next to having a dyno-tune done...right? :blink:

Does carburetor synchronizing have an effect on individual carburetor (pilot fuel/air) adjustments, or vice-versa? If so, will both tuning processes need to be performed simultaneously? :S

Thanks in advance!

Fool proof, too many other variables for true "getting carburetors precision-adjusted".

Individual pilot/slow-jet (Air/fuel) adjustments.
It's a 3 step process, takes about 5-10 seconds per carb once inserted into the head per cylinder...

Step 1) Idle... Turn to just barely bunson Blue color in the chamber.
Step 2) Slow ramp/twist of the throttle to ~ 3000rpm, should stay bunson blue in color.
Step 3) Quick blip of the throttle, should turn to yellow in color 1500-3000rpm then back to bunson blue.

Then carb sync & take her out for a spin.... You'll notice a difference on low-mid range response most definitely!
When all other factors such as timing, ignition pickup alignments, coil power etc... to spec, you should find no lulls/lags, flat spots etc... in how she performs.

Now outside of adjusting, I've found the tool a good trouble shooting tool when having carb issues.
Examples,
Plug conditions-Running too rich/lean,
Slight back fire due to running lean, leaking carb holder, maladjusted air/fuel mix.
Carb choke circuit malfunction, color won't change, provides a view-able confirmation,

Teaches you what you've always heard form old timers, Tweak by Ear.....

Example: Listen to the rpm change as it reaches bunson blue.
And this was only on the first plug, guess what happens when they all get adjusted correctly....

This sounds like a handy little tool. Anyone else have this kind of good luck with this.

The air screws have always gave me trouble trying to get them just right and I really like the sound of this tool for that.

KZB2 650

+1 used today first time. What a difference, wow! And easy. :kiss:
I was previously convinced that the pilot screws needed to be somewhat close to one another, turns-out...I was wrong.

I have the tool, haven't used it yet.
It is shorter than the normal spark plug.
Do I need the extension/adapter, or will it work fine being a little shorter and not in the combustion chamber fully?

rstnick

No extension needed, and for the inner two spark-plug holes...if you feed the black plug wire extension through the small plastic hex adapter, it makes threading that tiny tool into the spark-plug hole much easier than trying by hand without it, especially with a hot engine. I don't think it is necessary to use the supplied copper washer, since all you need to do is snug the tool down good by hand. Besides, the dang thing kept falling off the threaded end on every attempt to insert the tool with it on there.

I did the job immediately after fine-synchronizing the carbs, while the fuel tank was off and out of the way. That made the project much simpler, and it went quick. When finished, there wasn't a spot on the tool...no carbon, oil or anything!
I'm sold on it, and never would have known about the Colortune if not for reading about it on this totally awesome forum!

Special thanks to Old Man Rock

Thanks for the tips Dave.

I was referring to the length of the thread though on the tool, it is shorter than the spark plug thread length, so it will not reach into the combustion chamber as far as a spark plug does.

rstnick
No thread extension necessary. I thought about that too, but the tool is designed to work as supplied. I seem to remember reading a note in the handbook about the exposed spark plug threads below the tool...not to worry since the amount of time the tool is inserted is too short for build up of carbon to form on them.

" pilot screws needed to be somewhat close to one another"... BINGO!..... Never going to happen...
Even on my newer CR's, 1/4 - 3/4 turn difference is the norm...

Now get yourself one of these Morgan units, if you truly want them dialed in regarding Carb Sync!"

++++1 on the Morgan CarbTune. By far the best way to dial in your carb synch.

Where's the cheapest place to buy one from here in the States?

Any of you guys that have one, wanna loan theirs out for a small fee?