Gunson Colortune Review

(NOTE: The following was written for a blog post on a different forum. I posting it here for those that are considering purchasing a Colortune Plug.)

My wife and I both ride Yamaha XJ650 Maxims. Hers is an '82 and mine is an '81 model. They're what I call an inline 4 cylinder, but the factory service manual calls it a parallel 4 cylinder. Being as old as they are, they're also carburated as fuel injection was still relatively new for cars, let alone motorcycles. To make matters worse, the engine doesn't have one carburator... it has four of them; one for each cylinder.

At the end of last year, I hopped on her bike to ride it to work one day. I figured if she wasn't going to ride it (fairweather rider), I'd keep the oil moving, myself. To my most profound irritation, I discovered that right after it started, one of the carbs flooded, filling the crankcase with fuel which then ran into the air box and onto the ground. This, of course, requires a whole laundry-list of fixes to get the bike ready to ride again. Well, this last weekend, I trudged through that list and rode her bike to work yesterday. 8)

One of the things that I did was set the air/fuel mixture on the bike using a Gunson Colortune Plug. Here's a link to a short video I shot of the plug in action...

[flash=425,355]http://www.youtube.com/v/5BU-5FhX_Qc.swf[/flash]​

As can be seen in the above video, the plug screws into the sparkplug hole. What's unique about it is that it has a crystal which allows you to see what's going on inside the combustion chamber. This gives you a visual cue for setting the air/fuel mixture without having to buy a four-gas analyzer.

Here's a quote from the Colortune Manual that explains it a little better:

I can testify to the radical improvement in engine performance after using this tool. Even in the adjustment phase, I could hear the engine running better and better as I dialed in each cylinder. By the time I got to the last cylinder, the bike was idling smooth as a Swiss watch. I took it for a quick spin to see if the power was good throughout the Rpm range... It was!

If you've got an older, carburated bike and it seems a bit sluggish on the throttle, I'd highly recommend getting one of these Colortune Plugs to dial in the carbs. It'll make it run like a testosterone-poisoned teenager chasing after girls.

 

So true! This is exactly what I use to tune bikes at the North Texas Carb Clinic every year. Learned to do it on my bike after rebuilding the carbs and it absolutely made me their biggest fan. Great video of the plug in action showing a slightly rich mixture. Great job and review Gamuru!

 

I would add that:

a) adjust the valve first!

b) then synch! with the YICS blanking tool inserted if yours is a YICS engine.

c) then colortune, synch again, colortune again, synch again----all the while using the YICS blanking tool.

d) remove the blanking tool, then colortune one final time.

Sounds like a lot of work, but actually once the synch gauges are "installed", each iteration of the synch/colortune process only takes about 15 minutes, so you're looking at about an hours worth of tuning time (remember to allow engine cool-down between each round, both so that you don't crack the colortune plug and so that you don't melt the isolators on the YICS tool!).

The above process will make you a synch/colortune expert, and give your engine an incredibly precise tune.

P.S. if you skip step "a" (adjust the valves), you might as well skip steps b, c, and d, also...........

 

yeah i'm getting one.. I'm sold.

think you could get four and tune all at once?

 

Turbo....you could, but the issue you'll run into is that the colortune plug doesn't quite perform as well as a real spark plug, and thus the entire engine is going to be running "off power", and that's a tuning problem......

Plus, running all four plugs at once will EXTEND the time that each plug is in use, and heat is the killer of these colortune plugs (it cracks the clear "glass" viewing window).

 

Not to mention the cost...

 

Does anyone have, or want to shoot a video of the colortune changing color, and narrarate when it's too lean and right on? That would be cool!

 

Thanks for adding that. I was wondering about the synch first/last question and how many times I should adjust/check each.

That would be neat. I may have to get the camera out this Sunday and, with the wife's help, try and shoot some video as you've suggested. That is if the weather permits. :wink:

 

Here's a couple of decent videos of a colortune doin' its thang:

http://www.gadgetjq.com/Vulcan_1500_Idl ... e_Test.wmv

and

http://www.gadgetjq.com/Vulcan_1500_Mixture_Test.wmv

 

It didn't seem to me that changing the mixture affected the sync.

After doing both I'm pretty well convinced that it is pointless to try to adjust the idle mixture unless the sync is spot on and the idle speed is down to spec (or lower).

 

I bid on a couple Colortune kits a few years ago and got a 12mm and a 14mm, Invaluable !

When I tuned the 80 XJ650 I had with it, I couldn't believe how much smoother it ran and how much more responsive it was.

Also bought a Carbtune Pro as I had a few bikes at that time, great tool, Kinda pricey, but it works great.

Just got the Turbo running this week, took it for a short ride tonight down the neighborhood street and back, needs to be synced and colortuned... Gotta make that YICS tools first !

 

I used to be an Old School skeptic of the whole Colortune thing.

Now, after doing a few bikes ... and bringing never-before fine tuning to them ...

If you need a guy to appear in a Commercial for the Colortune ... gimme a call. I'll gush all-over the place about the thing.

Greatest little invention to come down the pike.
If you ain't got one ... you ain't tuned-up yet!
You can try tuning without one until you're blue in the face ... or, ...
Tune-up with the Colortune until it's blue ... then, go race!!!

 

i'd be interested in seeing any pics / video of your turbo with the colortune or what-not.

 

The older colortune 500 does have a larger volume and can affect tuning but not enough to really matter. I used one to tune my bike with great results. The motorcycle version with the large spark plug like insulator doesn't enlarge the cylinder volume so is very accurate. At carb clinics I hook up a set of carb sticks and watch it as I colortune. Faster and more efficient to do it this way. I can see if one cylinder is off by the vacuum so I know to colortune that one first. Normally I start with #1 and sync after finishing #4. Never have had to go back through all four a second time.

 

Rp,

We NEED to meet and go riding sometime now you got that old beast running. Never seen a turbo in action, there is a $2,500 turbo that runs near austin last I heard.

And that riding can be after(or before) a tune or two

Give me a PM if interested, I was in houston for the 19th win of the rockets. Had row 10 seats, They were Suuu.Weee.Tah.

 

hummm do you start with carb 3?

 

For colortune? Doesn't matter where you start. I prefer to go in order so I remember what I've done.

 

yes colortune. i was thinking on the line that #3 doesn't have a ajusting screw like the other carbs so you would use the idle ajustment screw to ajust it to the right color. then move on to the other carbs.

 

Well, actually it DOES have an adjusting screw.

 

miksatx, each of the carbs has a pilot adjust screw. I believe your thinking about the sync screws, there's one between 1&2, 2&3, 3&4.

Ass.Fault, I bought the Turbo as my last project before Fishing starts...Starts this week ! I got a ways to go before I get it road worthy, tires, brake lines, fork re-seal, ect...

turbobike, As soon as I get time to colortune & Sync the carbs I'll be sure and film it.

 

lol hummm so i'm messing with the wrong screws? cause i am turning on the screws i synch with.

 

The idle mixture screws are under small round pressed-in caps on the very front and top of each carb, just to the left of the choke enrichment "plunger" mechanism (on Hitachi carbs).

Those pressed-in caps will have to be removed before your can see the idle mixture screws.

Hopefully they have been removed by someone previously, as they usually have to be CAREFULL drilled out and then e-z-out extracted to remove.

And that process, of course, requires that the carbs be removed from the bike.

And while you have the carbs off the bike, well, that's a wonderful time to clean them........

 

As you Colortune you have to adjust the PILOT MIXTURE SCREW to the right AIR FUEL Mixture to sustain Idle.

As you do so ... you also have to Back Off on the Idle Adjustment Rod so that your Colortuning is not reliant on any AIR being drawn through the Butterflys.

You strive to get the Pilot Mixture correct to allow the Bike to Idle without ANY other AIR Source other than Pilot Air and Fuel from the Pilot Mixture Screw.

Accordingly, you have to adjust the Pilot Mixture to Not only be Balanced enough to allow the Bike to Idle ... BUT >> Also, RICH enough to sustain Ignition when the Butterflys are Opened and the onrush of Intake AIR
Mixes with the Pilot Mixture for the brief moment that the Intake AIR
precedes the Main FUEL Jet's supply drawn-up from the Emulsion Tube.

This means you have to Colortune to the RICH SIDE of the window.

Picture the lines on a parking lot where you are supposed to park your car.
The area between those to lines, where the car fits is the Window.

There is a "Window" in Colortuning ... too.

If the Car is too far to the right line ... the Passengers can't open their doors without banging the doors into the car in the next stall.

If the Colortuned Mixture ... although BLUE ... is too close to being on the Lean side ... there isn't enough Fuel for the OFF IDLE Mixture and the Bike will hesitate getting out-of-the-hole ... UNTIL the MAIN JET Supply reaches the Air Flow and a correct Air-Fuel Mixture is present.

If the Car is too far to the Left or Over the Line ... you can't get out.
If you Colortuned Mixture is too RICH ... there is too much FUEL and the Bike won't perform until that Mixture is Leaned-out to prevent too much FUEL from entering the Combustion Chamber and flooding you out.

The Colortune process is YOU finding where to park the car without searching the whole lot for a parking place.
You observe the Burn and find the Line to pull into without a long and involved searching and driving all over the place looking for a place to park.

The BLUE is the two lines.
That your window.
You will Idle and run within two lines.

AFTER you Colortune and get the Bike running pretty good ...
You do a little more work and get it running GREAT!

The WINDOW after Colortuning is 3-Degrees.
Three degrees of Pilot Mixture Turning is about the width of a Nickel.

You Colortune and get within 3-Degrees of near perfection.
The Pilot Mixture Screw will need further adjustment ... within the lines of being tuned for an Air~Fuel Mixture that will Idle the Bike and get you out of the hole.

Staying within those 3 degrees you will be able to select:

Fast. Rapid acceleration and extremely quick RPM's advancing due to a Lean, highly explosive Mixture.
Pilot Mixture Screw turned IN 2-3 Degrees for Power and Lean Mixture for heavy engine braking.

Smooth. Luxurious Cruising and smooth and cool running for Long-haul and all day riding. Engine coasting upon closed throttles.

Or: Your own personal TWEAK>

Based on TUNING the Pilot Mixtures to your own liking ... something in the middle for messing around and zooming and cruising without extra fuel for pulling all day along the Interstate.

The trick is watching your Plugs and NOW treating the RACK as FOUR Separate Carbs.

Read the Plugs.
Look for the color and the effect the Mixture has on the Plugs CENTER electrode.

Do NOT run CLEAN!
Do NOT run causing the Plugs Center electrode to overheat and cause the Ceramic to hairline or erode.

Other than that:

You fought like hell to be able to tune your own bike ... so, tune it the way you want to ride it. Just don't get carried away by the rush of running Lean and having Space Shuttle Power and a Lean Burn because you WILL do damage to an engine running it too lean.