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Thread: Questionable Carb Tuning Tool - Colortune

  1. #1
    Alps Adventurer GlobalRider's Avatar
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    Exclamation Questionable Carb Tuning Tool - Colortune

    At the request of a member on this forum (no names mentioned), I'd like to relate my experience with the following product in an attempt that you'll avoid the grief.


    Colortune Product Warning


    If you are considering the purchase of a Colortune Carburetor Tuning Aid, you might want to reconsider.

    I originally saw this product advertised in the BMW MOA Owner's News by Bing Agency International (BAI). They claim that this product enables you to "adjust your carburetors precisely". It does so by providing you with what is essentially a spark plug with a transparent insulator. The transparent insulator enables you to see the color of the combustion while carburetor adjustments are made. This is much like adjusting the color of the flame of an oxy-acetylene torch.

    The principle of operation is not the reason for the warning although I have added a few comments regarding this at the end.

    The Colortune that I received did not meet the "SAE" or "Revised British" specifications for spark plug dimensioning. Unfortunately I wasn't aware of this until it was too late. The Colortune, although threaded in by hand before lightly tightening, was difficult to remove from the cylinder head of my BMW. Luckily only very minor damage resulted. I took the COLORTUNE along with two randomly selected spark plugs to work for dimensioning. The BOSCH was dead centered within the SAE spec and the NGK was towards the lower end.

    The major diameter of the Colortune (0.5498") was greater than the maximum set out by the "SAE" and "Revised British" Standards. I brought this to the attention of both BAI and Gunson, the manufacturer in England. Gunson claimed that the measurement that I provided them with fell right within THEIR tolerances of 0.5455" to 0.5505". Sure enough it does; unfortunately THEIR tolerances didn't coincide with neither the "SAE" or "Revised British" standards. I questioned Gunson as to the source of their standard but no response as of yet.

    As for the Colortune, I can say that it would've made an expensive paperweight if I hadn't been offered a refund. As far as using the Colortune to set up carburetors ÔÇ£preciselyÔÇØ; forget about it. Set them up using the manufacturers recommendations and then make final adjustments (which the Colortune couldnÔÇÖt do in any case), on your own. Makes me wonder if BAI or Gunson know the definition of the word "precisely". Additional information may be found in the 23rd edition of the Machinery Handbook.

    The BMW MOA directors were informed of the problems I experienced shortly after I purchased this product in 1992. Although one director took the time to look into my problem, I was basically ignored by the BMW MOA. Their tech expert that contributed to the monthly magazine in the past, took my side and agreed with my findings. More recently (2000), one of the directors looked into the matter only to inform me that a sample that he received measured within tolerance. IÔÇÖm not arguing his findings. The FACT that MY unit didnÔÇÖt meet specifications requires that BAI and GUNSON come good for damages to my motorcycle due to the use of their ÔÇ£totally uselessÔÇØ product.

    If you choose to use this bogus product, do yourself a favor and measure the major diameter of the threads to see it they indeed are within specifications. If they do meet specifications, youÔÇÖll still be using a product of questionable use.

    As a 12 year member of the BMW MOA, I'll add that I take any product evaluations in the Owners News very lightly and more of a "trumpet blowing' session. For any product evaluation to be unbiased, especially if the product is advertized within the pages of the Owners News, it would have to be done by a person that provides a write-up of all pros and cons of the product. Most of the time, I just see the pros.

  2. #2
    Loose Cannon flash412's Avatar
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    I bought one. It is a piece of crap. If you want one, I'll sell you mine for half price. It has about ten minutes use on it. There are several MUCH better ways to set up carbs than by using Colortune.

  3. #3
    yenkofu
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    I'll add that I take any product evaluations in the Owners News very lightly and

    another crap as
    http://www.youtube.com/watch?v=L-RrK...feature=digest

    yes !!!
    " I'll add that I take any product evaluations in the Owners News very lightly and more of a "trumpet blowing' session."

  4. #4
    Alps Adventurer GlobalRider's Avatar
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    Quote Originally Posted by yenkofu View Post
    You might want to send it back, but before doing so, replace the battery with a known good one.

    I am able to zero the meter very easily even at max sensitivity.

  5. #5
    Grammarian no, Rider yes ISAMEMON's Avatar
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    I wonder if times have changed.
    I first started using colortuens in the 1960's tuning multiple carb cars such as jags, triumphs, mg's etc
    and I was more accurate then a gas pipe sniffer because the sniffer smells the final exsaust,
    you can have one lean carb and one rich carb, and balance at the tail pipe
    I have two of them one for each set of carbs on a car

    a pair of those and a unisyn, and I was one of the best carb guys in fla, having cars brought to our shop from all over



    the ones I use were both built in the 60's, they came in a nice box, wtih multiple plug adampters for reach etc

    I guess quality etc has changed, sorry that you all have had a bad time with them

    but for me, on my bmw bike, I have to admit, the best way is riding, pulling polugs and adjusting for richness
    for balance I have an electronic one, and the home made vacum one detailed in airheads forum

  6. #6
    criminaldesign
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    I've resorted to using my ears and even mixture turns synching the carbs with the tach. I checked the plugs this afternoon after 2000 miles and they look fine and even. Currently I have my idle around 15000rpm. I know it's above the usual but I like the steady rumble, doesn't sound like it want's to putter out. I removed all the emission treats, it burps more but that's quite alright.

  7. #7
    Registered User skiteach's Avatar
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    The BOSCH was dead centered within the SAE spec and the NGK was towards the lower end.

    Back when air cooled VW;s roamed the roads, we were told to use Japanese manufactured or Bosch plugs. The reason was the threads were rolled as opposed to cut. We repaired many spark plug holes that had galled and de-threaded. Mostly the threads were ruined by some popular Am plugs, occasionally by the factory installed Bosh- being left in for way too many miles. # 3 cyl was a little hard to get to and the flat raters woudn't bother taking the time to remove.
    Have a Colortune somewhere, never did use it. My Unisyn worked very well for any/all of the multiple carb setups I ran across
    '73 R75/5
    Never had a bad day skiing!

  8. #8
    Never a dull moment
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    Quote Originally Posted by criminaldesign View Post
    Currently I have my idle around 15000rpm. .
    Dang, I didn't know Airheads were capable of Formula 1 racing!

    (that's good to know since I can't seem to keep mine happy at 1,000 rpm either - it tends to hang there for a few seconds then stumble and fade. It settles in at 1200 rpm just fine - not a whimper)

  9. #9
    criminaldesign
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    Quote Originally Posted by RonKMiller View Post
    Dang, I didn't know Airheads were capable of Formula 1 racing!

    (that's good to know since I can't seem to keep mine happy at 1,000 rpm either - it tends to hang there for a few seconds then stumble and fade. It settles in at 1200 rpm just fine - not a whimper)
    you should see her in 5th at 60,000rpm. Shoot to the moon.

  10. #10
    Never a dull moment
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    Quote Originally Posted by criminaldesign View Post
    you should see her in 5th at 60,000rpm. Shoot to the moon.

  11. #11
    Registered User lkchris's Avatar
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    Colortune is a product about 50 years old, i.e. popular with guys with MGs, Sprites, etc. It's a blast from the past.

    There's really nothing to be gained doing anything but setting an Airhead to factory specs--BMW's middle name ain't "motor" for nothing.

    And, you'll note NASCAR guys "read the plugs," and don't use stuff like Colortune. Knowing that, now you can do a high rpm ignition cut and play to your heart's content.
    Kent Christensen
    21482
    '12 R1200RT, '02 R1100S, '84 R80G/S

  12. #12
    Administrator 20774's Avatar
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    Reading plugs is harder with no-lead fuel. IIRC, the NASCAR boys (and girls) are still using leaded gas.
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  13. #13
    Registered User lkchris's Avatar
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    Quote Originally Posted by 20774 View Post
    Reading plugs is harder with no-lead fuel. IIRC, the NASCAR boys (and girls) are still using leaded gas.
    They switched to unleaded a few years ago.

    And, they're still reading plugs.
    Kent Christensen
    21482
    '12 R1200RT, '02 R1100S, '84 R80G/S

  14. #14
    535IS
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    Whoa! SEVEN YEARS!


  15. #15
    Administrator 20774's Avatar
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    Quote Originally Posted by lkchris View Post
    They switched to unleaded a few years ago.
    Right you are...I guess I hadn't been paying attention!
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

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