Colortune, is it needed?

[nutz4spd]

I was reading an article on how to properly sync the carbs on the GS. They were using a Colortune to check on the fuel mixture and make sure it was correct. Is this Colortune really necessary or can the mixture be check another way? After putting a couple of new mixture screws in the carb I need to make sure everything is set properly.

 

[xkaes]

Hello,
I have never heard of Colortune. I use an "old-fashioned", four-column, mercury carb balancer. Perhaps if you have a link to Colortune, you'll get more response.

 

[Burque73]

I've heard the Colortune works well if your bike has VM carbs but not so well with CV type carbs.

Here's another way.

1. Take off the tank, set up some form of remote fuel supply.
2. Set the idle mixture screws at 2 turns out.
3. Warm up the engine and let it run.
4. Adjust the idle to approx. 900 rpm.
5. SLOWLY turn the screw at carb #1 in - at some point, the rpm are going to start dropping and the engine won't run as smoothly.
6. Start turning the screw back out until you get the highest rpm and a smoother sound from the engine.
7. At some point, turning the screw out further won't make any difference (and even further out may again take away the smoothness and the rpm).
8. You want your screw turned IN as much as possible without affecting the rpm/smoothness.
9. Re-adjust the idle to 900 rpm.
10. Stop the engine to let it cool down a bit or place a big fan in front of the engine and do this while the outside air is cooler (morning/winter).
11. Proceed with carb #2.
12. Repeat steps 4 through 10, as necessary, for all carburetors.
13. When complete, re-adjust the idle knob for the correct rpm as per your factory manual (usually 1050 rpm +/-100 rpm). In any case, do not idle below 900 rpm as this may result in insufficient oil flow.

Found here...http://members.dslextreme.com/users/bikecliff/images/highest_rpm_plug_chop.html

 

[Rich82GS750TZ]

there are 44 threads in the archives w/ the word "Colortune" in the Thread Title
https://www.thegsresources.com/_forum/search.php?searchid=3222654

 

[Burque73]

there are 44 threads in the archives w/ the word "Colortune" in the Thread Title
https://www.thegsresources.com/_forum/search.php?searchid=3222654

Rich, that link is a dead end.

 

[nutz4spd]

Hello,
I have never heard of Colortune. I use an "old-fashioned", four-column, mercury carb balancer. Perhaps if you have a link to Colortune, you'll get more response.

This is the what the Colortune is. http://www.carbtune.com/colortune.html

 

[Guest]

The utility of a colortune for me was for re-jetting.

 

[Rich82GS750TZ]

worked for me. Maybe its dependent on my login

Anyway,
When searching, use ADVANCED, type keyword Colortune, select titles only (the only way to get meaningful results). you'll see 44 entries.

 

[cowboyup3371]

Carbtune is the way to go to sync your carbs; Colortune was shown to not be as effective with CV carbs as it might be with the VMs

 

[Grimly]

Oddly enough, it was designed for use with CV carbs.
However, it only really comes into its own at idle and assuming a standard set-up of needle, spring, jets, etc, like most car owners of the day with an SU carb.
It CAN tell you about running conditions further up the rev range, but really you need a set of them and who's going to splash out for four Colortunes.

 

[chuck hahn]

Hers my 2 cents seeing i use mine regularly on VM and CV carbs.

VM carbs are EASILY tunable via the side air screws. Also it tells how you pilot circuit is doing at idle. I will set the idle at 3000 to3500 and adjust air screws for the nice bunson blue color. Then i back off the idle to 1100ish and see what color the pilot circuit is. If its showing a bit lean you can adjust the air screw at idle and again run it up to 4000 or so and see what the main circuit tells you now. If they both are reasonably good then so be it. If the main circuit changes odds are youll need to tweek the pilots GENERALLY if carbs are stock jetting you just adjust the air screw for best color at idle then run it up to view the main circuit. Maybe tweek air screw for that happy middle ground setting.

CV carbs are another animal. The colortune will tell you two things. When the mixture screw shuts off fuel at idle and what the main jets doing at higher highway typical RPMs. Turn the miture screw in till the flame goes awaythen out till it comes just comes back solidly. Then go out another half turn. This gets real close to being right for idle and to supply enough fuel to transition onto the main circuit smoothly. IF it seems a bit stumbly between 1/8 to 1/4 throttle add 1/4 turn out and test ride again.

Second thing is it will show how the main circuit is doing. I just did a KLR the owner was gonna junk because" it wont run past 1/3 throttle". the previous owner put on an aftermarket pipe and sure enough the colortune showed the flame going away around 1/3 throttle. Opened carb to find the stock 145 keihin main jet in there. I went up 2 sizes to a 155 and bingo...full throttle monster. Colortune confirmed the jet choice was spot on. OWNER texted me when he got home and told me he was :STUNNED" on the ride home and now he cant sell it.

 

[chuck hahn]

Grimly, i have two. I put one in each left side and do my thing....switch to right side.

 

[Guest]

Hers my 2 cents seeing i use mine regularly on VM and CV carbs.

VM carbs are EASILY tunable via the side air screws. Also it tells how you pilot circuit is doing at idle. I will set the idle at 3000 to3500 and adjust air screws for the nice bunson blue color. Then i back off the idle to 1100ish and see what color the pilot circuit is. If its showing a bit lean you can adjust the air screw at idle and again run it up to 4000 or so and see what the main circuit tells you now. If they both are reasonably good then so be it. If the main circuit changes odds are youll need to tweek the pilots GENERALLY if carbs are stock jetting you just adjust the air screw for best color at idle then run it up to view the main circuit. Maybe tweek air screw for that happy middle ground setting.

CV carbs are another animal. The colortune will tell you two things. When the mixture screw shuts off fuel at idle and what the main jets doing at higher highway typical RPMs. Turn the miture screw in till the flame goes awaythen out till it comes just comes back solidly. Then go out another half turn. This gets real close to being right for idle and to supply enough fuel to transition onto the main circuit smoothly. IF it seems a bit stumbly between 1/8 to 1/4 throttle add 1/4 turn out and test ride again.

Second thing is it will show how the main circuit is doing. I just did a KLR the owner was gonna junk because" it wont run past 1/3 throttle". the previous owner put on an aftermarket pipe and sure enough the colortune showed the flame going away around 1/3 throttle. Opened carb to find the stock 145 keihin main jet in there. I went up 2 sizes to a 155 and bingo...full throttle monster. Colortune confirmed the jet choice was spot on. OWNER texted me when he got home and told me he was :STUNNED" on the ride home and now he cant sell it.

That's exactly how I have used one. To confirm jetting.

 

[wymple]

Chuck was showing me and my son that KLR when were down there a couple weeks ago. I thought his ability to to tune with it was pretty darn amazing.

 

[93Bandit]

CV carbs are another animal. The colortune will tell you two things. When the mixture screw shuts off fuel at idle and what the main jets doing at higher highway typical RPMs. Turn the miture screw in till the flame goes awaythen out till it comes just comes back solidly. Then go out another half turn. This gets real close to being right for idle and to supply enough fuel to transition onto the main circuit smoothly. IF it seems a bit stumbly between 1/8 to 1/4 throttle add 1/4 turn out and test ride again.

Please forgive me for reviving an old thread, but I just ordered a colortune to work on my 83 850 and I discovered post-purchase that the colortune doesn't work as well for CV carbs.

Based on what chuck hahn says above, with CV carbs you're not looking for the blue flame but rather when the flame just appears + 1/2 turn? Just want to confirm you're not looking for color since you don't mention it?

 

[trent]

Please forgive me for reviving an old thread, but I just ordered a colortune to work on my 83 850 and I discovered post-purchase that the colortune doesn't work as well for CV carbs.

Based on what chuck hahn says above, with CV carbs you're not looking for the blue flame but rather when the flame just appears + 1/2 turn? Just want to confirm you're not looking for color since you don't mention it?

I bought colortune years ago and never used it, was thinking about seeing if anyone wanted it...Can't remember what I paid for it.

 

[Who Dat?]

Based on what chuck hahn says above, with CV carbs you're not looking for the blue flame but rather when the flame just appears + 1/2 turn? Just want to confirm you're not looking for color since you don't mention it?

That is correct. I have seen a couple sets of CV carbs that showed differences in color, but MOST of them will just show the blue flame slowly puttering out, then stopping, as you turn the mixture screw IN. When you start to turn it OUT (SLOWLY), you will see the blue flame start puttering back in, then going steady. Add about 1/2 a turn more, as Chuck says. That will definitely get you in the ballpark.

 

[93Bandit]

I bought colortune years ago and never used it, was thinking about seeing if anyone wanted it...Can't remember what I paid for it.

Bummer, would have probably been easier to get from you rather than waiting for it to ship from the UK. Mine finally arrived today.

 

[93Bandit]

That is correct. I have seen a couple sets of CV carbs that showed differences in color, but MOST of them will just show the blue flame slowly puttering out, then stopping, as you turn the mixture screw IN. When you start to turn it OUT (SLOWLY), you will see the blue flame start puttering back in, then going steady. Add about 1/2 a turn more, as Chuck says. That will definitely get you in the ballpark.

Perfect, thank you!

 

[chuck hahn]

To correct Cowboys post, i think he meant TUNE carbs not sync them. Syncing requires vacuum guages. AND just an FYI. If you use those blue emgo guages be sure to sync the neeles first. Get a few vacuum tees and hook all 4 dials to a single vacuum port. Remove the front lenses and theres a slotted brass screw on the dial faces. Set all 4 dials the same and then youre assured an accurate syncing. And yes they are actually very good syncers