colortune question

Today was the first time I've ever used a colortune before. It took me a little while to figure everything out.

I can get an orange color, and I can get a blue color. I can't tell any difference between when I first start seeing blue and the blue I get with the mixture screw turned in several turns.

It all looks the same to me. The instructions mention a whitish blue color as being lean.

Should I be able to tune my idle mixture lean enough to see a different color?

 

I think the idea on the first setting is to start with the orange flame (rich) and turn until you start achieving bunsen blue (lean) not whitish blue, then stop. The idea is not run a tad lean but not go further than that. The instructions say that the point where it turns from yellow to blue. More specific, about 1/2 way from when it turns blue to where the idle drops a little.

 

Sometimes it pays to read the instructions.

"Whitish blue indicates a mixture which has less petrol content (lean).
note: this colour is more easily seen at higher speeds. At idle, engine instabilityand misfiring may occur before this weak mixture and pale shade of blue is fully visible."

The way I understand that is the only time I would see the whitish blue color would be if the carbs were jetted very lean and I was running at a higher RPM with the colortune installed. Correct?

 

Right, the whitish blue flame is real lean. Here is chart I posted on another thread. The 1st color strip is the progression of the first test. What you should see while making the adjustment. Start from rich (yellow) and go until it turns bunsen blue than half way from that point to were the rpm drops slightly. Harder to hear on motorcycle with four carbs as opposed to a car which one carb (usually) feeds and will effect all the cylinders at the same time. The second and third color strips (tests) on the chart are not adjustments but used to diagnose. Test three for example starts bunsen blue (idle 1000 rpm) and the open the throttle letting fuel more in (thereby goes yellow;rich). Then lets go throttle and goes lean again back to idle.

Here is the chart: Gunson Colortune

 

Do you think it would be possible to use an inductive pick up type tach clamped on to the plug wire for the cylinder being tested to precisely pinpoint this location?

 

I don't know, to be honest, when I did mine I just let it turn blue and then maybe another one eight to quarter turn. Keep in mind, they expect you to have one of these testers hooked up to each cylinder (since four carbs) when doing the tests. That means four in our case, like that would cost over $200.00, yikes!. I guess if I did this for living I would have four in my tool chest, LOL. But then again, hopefully I would be skilled to do it by ear instead. I think you will be alright as long as you don't go too lean. How it runs will be the real test.

 

The bike runs really nice and I want more saddle time before I go super tweaker on the engine.

When tuning car motors I would adjust for the Highest RPM. I'm just curious if the other cylinders would keep the RPM on the cylinder being adjusted from having a noticable rise or fall.

Just thinking out loud but I would think that any variance in RPM would be very small. I'm assuming that the waste spark system would make the tach read the number of times that 1 and 4, or 2 and 3 fire per minute.

Maybe adjust 1 and 4 to highest RPM then the same for 2 and 3

multiple carbs are just a little confusing :?

 

You only tune one at a time. Having a colortune in all the cylinders at the same time doesn't work very well. We tried it out at the cnycc.

 

OK now I'm wondering about tuning with a tach intead of the color tune.

Do you think it would be possible to "tune by Eye?" (watching a tach for highest idle speed on each cylinder)

 

Not doubting you, your experience may be different. I only have one colortune, and did one at a time (PIA), so I don't know if four would be better than one. I only stated that because that is what I read in the the color tune instructions which I promptly ignored: Colortune Handbook, section 4.c, third and forth bullet.

 

Others with more experience will hopefully answer that for you Dave, but I had trouble doing it so that was the reason for buying the Colortune. It is supposed to be more accurate as well.

 

Thanks XJOE550, maybe after I put some more miles on the bike I'll play around with different tuning methods, see if it is possible.

 

Maverick, what kind of issues did you guys run into with all four? Got me curious, LOL.

 

Some real good old-timers could do a pretty fair job tuning "By ear"!

I bought a ColorTune.

 

This is what I observed with my recent colortuning:

There is a VERY small adjustment window when you go from yellow to blue, like Rick says, width of a nickle or a dime. Once you get past the transition from yellow to blue, there is a much wider window to adjust, say 1/4 to 1/3 of a turn before you get into lean/drop a cylinder territory.

When i first tuned, i went to JUST off yellow, sort of a yellow blue mix. This was WAY too rich after a few cold engine --> hot engine cycles, plugs were also quite black, not sooty, but black. I would get bogs at idle, and just off idle.

Leaning out the pilots a little at a time (nickel width adjustments), I found that about 1/4 turn leaner from where I was originally, had a nice idle, and off idle there was no bogging. Colour on the plugs was better as well (This is were you get that "colour on only one side of the plug" deal).

Hopefully this helps some.

 

The problem with using a tach to register RPM change is that most commercially available tachs are built to cover a broad range of RPM's and we are trying to notice one or two RPM at the 500 to 1500 RPM range. In this age of computers, I am sure that some clever techie could breadboard something using Radio Shack parts, and if they do, I would be interested in the schematic.
It wouldn't make any difference which cylinder you hooked it to, since they are all connected to the crank, so a single pick up, and I would suggest the impulse from the pickup coil, would do to drive the tach. The reason for the pickup coil choice is that the plug impulse has to go through a lot of electronics before if manifests as a spark, and thus a pulse for the tach to read. The pickup coil would be a "cleaner", more accurate signal.

CZ

 

That's why they make these: Tach and Dwell Meters
A digital meter will be easier for most people to read.
In all honesty though, using a Colortune is much easier method, than using the RPM drop method, when dealing with multiple carbs.

 

I have found that a dimly lit room makes it easier to see the color in the plug window. My neighbors think I'm crazy working on my bike at night with the light turned off in the garage.