67 Atlas

Not so sure that there's any real benefit to using the Colortune. It's fun though.

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If you can get 100% right-then there is no need for it-but if you are even 1/16 of a turn or indeed 1/32 of a turn out, then it’s out.
So, the blue flame principle means absolutely nothing to you :?:
I take it you are not a chemist or a heating engineer , or ever used a Colortune at all:?:

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You can apply as much rhetoric as you like, but it's not that sort of debate. I work with chemists and I wouldn't leave some of them in charge of the cat, never mind let them near an engine.

I own two Colortunes! You can call me "Two-Colortunes."

I've stopped using them, because you can get it idling just by twiddling the screws and listening. Keep slowing it down with the throttle stops, then searching for best firing with the mixture screws. Repeat.

Screwing either throttle stop in by1/16 of a turn should speed the engine up. If one doesn't do that, screw out the one on the other side a little bit and try again.

The other reason my Colortunes lie idle is because I get best throttle response by temporarily tightening the throttle cable so the slides are just off their stops and then tuning for best running at this fast idle by twiddling the mixture screws. Incorrect procedure, but it helped me.

beng said:

A long time ago I was talking to an old Triumph dealer who agreed with me that if you are going to ride an old British bike, then you are either going to spend an hour on maintenance for every two hours you ride it, or you are going to have to be wealthy enough to pay someone else to do it.

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That is absurd.

I've owned over 40 classic Triumphs, currently have 10 running, and manage many trouble-free miles with nothing more than regular oil changes, fresh spark plugs every few months, trickle chargers on the batteries, minor clutch adjustment, and once or twice a year valve lash adjustment.

About 2 hours for all of the above returns at least a THOUSAND miles minimum; more if it's highway miles.

beng said:

A long time ago I was talking to an old Triumph dealer who agreed with me that if you are going to ride an old British bike, then you are either going to spend an hour on maintenance for every two hours you ride it, or you are going to have to be wealthy enough to pay someone else to do it.

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In 2007, I scratch built my 650 Bonneville with all OEM & pattern (EMGO) parts except a Sparx electronic ignition and have raced 21 road races including Roebling Road, Daytona, Grattan, Road America, Willow Springs, Texas World Speedway, Barber, Sandia & Miller; also made a pass down the salt at Bonneville and have made a couple of passes at the Texas Mile. That also includes numerous practice sessions, typically 3 or 4 per event, and using the bike as a pit bike for working Texas Mile weekend events 4 or 5 times over the last few years.

In all that time, I have done nothing more than change the oil twice a year, plugs every other race, cleaned the carbs once due to the bike being in an open pit through a thunderstorm with tornados (Road America in 2008), and check valve lash just before every race weekend. The only failures have been a broken front brake cable and loose ignition wire (both during practice), a muffler that fell off one lap before the end of a race, and a coil wire shorting out under the gas tank, also one lap before the end of a race (still scored points in both of those).

I have spent no more than 10 hours on the bike since I first fired it up 6 years ago. I can put some fresh gas in it right now, and ride it till it runs dry.

Nortons are no worse or better.

grandpaul said:

beng said:

A long time ago I was talking to an old Triumph dealer who agreed with me that if you are going to ride an old British bike, then you are either going to spend an hour on maintenance for every two hours you ride it, or you are going to have to be wealthy enough to pay someone else to do it.

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That is absurd.

I've owned over 40 classic Triumphs, currently have 10 running, and manage many trouble-free miles with nothing more than regular oil changes, fresh spark plugs every few months, trickle chargers on the batteries, minor clutch adjustment, and once or twice a year valve lash adjustment.

About 2 hours for all of the above returns at least a THOUSAND miles minimum; more if it's highway miles.

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Think about it. How do old British bike dealers make their money?

Bernhard said:

Or, what do I know! -The person using the Colortune was colour blind :!:
Any 10 year old child, who could get a Bunsen burner right, could operate and get the Colortune spark plug right.

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This was a demonstration of a color tune.
On a Commando, selected at random.
Apart from the color being extremely hard to see, in daylight, to get a blue color it had to be lean as lean.
We all concluded it was rubbish....
??

Tell us what bikes you have used it on, and how it improved the running.

Rohan;
With an attempt to answer your question, I have pinched this from the Commando thread;
time-bury-the-amals-t17436.html
Quote; “ by Unclviny » Thu Sep 19, 2013 7:51 am
There are 2 major-things with Amal’s that confound folks:
1. they fight old, worn out carbs that will NEVER work properly
2. they WAY over tighten them, warping the bodies.” Quote.

RE; “This was a demonstration of a Color tune.
On a Commando, selected at random.
Apart from the color being extremely hard to see, in daylight, to get a blue Colour it had to be lean as lean.”
You have answered your own question, I NEVER attempt to use the Colourtune in daylight, not even with the black plastic tube supplied with the kit. The human eye will not see the colour showing when firing of this either unless you have a tick over of at least 1000rpm, whilst using a Colortune, when corrected return the cars to the normal idle rpm.
I have use it on the following, Austin Minis, Bedford 2.300cc vans, Norton Atlas, various Hondas from single cylinders to 4 cylinders, Suzuki SP370, Yamaha RD 350Lc two strokes. On some like the Yamaha I could see that the carb was rubbish which I successfully replaced with a non-standard but better carbs.
I will soon be using it on a second Kawasaki GPZ305 when I can get a screwdriver that will give me access to the airscrew.
All showed slightly better acceleration from standstill when correctly done-some I didn’t need to move the airscrew more than a tiny amount,

If you can still adjust the airscrew needle in an Amal, and it makes a difference, then it is not worn out.
That comment is just an insult aimed at brit bike owners... !?
Which idle under 1000 rpm, quite well I'd comment.

And doesn't the idle screw in (most ?) japanese carbs adjust the fuel supplied, not the air supply to the idle ?

I'd find it difficult to believe anyone could detect an actual difference in the performance in the low end of the rev scale.
How it sounds and feels maybe, but without some extremely accurate measuring equipment, a performance difference ????

Rohan said:

I'd find it difficult to believe anyone could detect an actual difference in the performance in the low end of the rev scale.
How it sounds and feels maybe, but without some extremely accurate measuring equipment, a performance difference ????

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You're kidding, right?

Difference in performance can be VERY noticeable at lower RPM when accelerating from a stop, and roll-on acceleration at low speeds in traffic. Stalling at traffic lights, etc...

Triton Thrasher,
'I work with chemists and I wouldn't leave some of them in charge of the cat, never mind let them near an engine.'

I can tell you are an engineer.
I am a tertiary qualified industrial chemist, and worked professionally as one for forty years, in various industries including explosives manufacture. I also worked as quality manager for a company making gas fired aluminium melting furnaces.
I can out-engineer most engineers, especially when it come to motors. If you believe you can adjust fuel/air ratio by visual assessment, you are kidding yourself. Why do gas plumbers use gas analysers to assess the carbon monoxide emitted from gas heaters, if it can be done by eye without the expense of the calibration gas used to set up their meters ? I can believe that the colourtune technique might work if the measurement was done by spectral detection, otherwise ? ? ?
I wonder if you could look down the black tube while riding the bike so that the engine is loaded to get a better assessment of the fuel mix ?

Rohan,
'I'd find it difficult to believe anyone could detect an actual difference in the performance in the low end of the rev scale.
How it sounds and feels maybe, but without some extremely accurate measuring equipment, a performance difference ????'

You don't need 'accurate measuring equipment' to feel the performance difference,
TORQUE WINS RACES !
You have obviously never ridden a four stroke race bike with extreme cams and megaphones and an inadequate gearbox. Why do you think most Japanese two strokes have six gears ? - no bottom end. When you are dicing with a group of other riders on a tight circuit, you need all the bottom end you can get. A top end motor is great if your riding style is only point and squirt.
With a torquey motor and a 6 speed close box, you can climb to higher speed at the ends of the straights, especially if your bike is set up to self-steer out of corners, so you get the power on earlier. If it tends to run wide, even a top end motor will get you into trouble if you don't go slower until the bike is vertical. However if the motor is 'top end' and the bike self-steers, it will probably step out and high-side you.
My old Triumph 500 was extreme 'top end', had nothing under 5,500 RPM. With a 6 speeder it might have been bearable, it is still somewhere I never want to go again. My Seeley 850 is much faster,safer and much less stressful.

acotrel said:

You don't need 'accurate measuring equipment' to feel the performance difference,
.

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If you can win races on the extra torque of an engine at idle,
then you are a better shemale than we are, gunga din. !!

Remember, the colortune only (supposedly) sets the mixture strength at idle.
It warns you that tuning at speeds beyond idle is beyond its capabilities.

So an extra maybe 1% of maybe 2 hp at idle isn't even going to give a speed advantage over the local flies ??

Thats if you get any power advantage whatsover - to get a blue flame at idle, most engines are going to be running quite lean.
Based on the demo we saw, anyway.
The engine is more likely to stumble as you give it the berries...

Once again I find that the people replying to this webpage have gone off tangent on the item being discussed,------ I never said at any time that the Gunsons Colortune method would be any help on a racing engine, certainly not on a full race cam fitted with similar full race carbs to the Amal GPs which do not have a pilot jet for ticking over whilst stationary.

As we have appeared to now changed the subject to racing engines , some of you out there will have ridded a Yamaha watercooled TZ 350, which was at first only had a power band from 8,000 -12,000rpm, then they changed the carbs to powerjets, which helped to drop the powerband to 7,500rpm, making the bike slightly easier to ride (still a bugger though, if you didn’t know how to ride it) as for gearboxes, close ratios were made for the racing bikes for a reason, if you couldn’t get that right, then you should have had the gears made to suit the engine.
True the high revving bikes had no torque, and had to be fitted with more and more gears in the gearbox in some cases (there were some smaller bikes with 18 gears :!: ) but that was racing :!:

acotrel said:

Triton Thrasher,
'I work with chemists and I wouldn't leave some of them in charge of the cat, never mind let them near an engine.'

I can tell you are an engineer.
I am a tertiary qualified industrial chemist, and worked professionally as one for forty years, in various industries including explosives manufacture. I also worked as quality manager for a company making gas fired aluminium melting furnaces.
I can out-engineer most engineers, especially when it come to motors. If you believe you can adjust fuel/air ratio by visual assessment, you are kidding yourself. Why do gas plumbers use gas analysers to assess the carbon monoxide emitted from gas heaters, if it can be done by eye without the expense of the calibration gas used to set up their meters ? I can believe that the colourtune technique might work if the measurement was done by spectral detection, otherwise ? ? ?
I wonder if you could look down the black tube while riding the bike so that the engine is loaded to get a better assessment of the fuel mix ?

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Apart from that you might happily leave yourself in charge of the cat, I cannot tell which parts of anything I wrote, is being argued against here. I certainly didn't say I could set mixture "by visual assessment," or say anything against (or even about) gas analysers.

No, I don't think I'm an engineer, either.

Bernhard said:

some of you out there will have ridded a Yamaha watercooled TZ 350, :

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The subject here is a Norton Atlas.
Suggest we stick to it....

There are other forums for blue smokes.
Bet they don't race tune them with colortunes either.
If they expect to win, anyway....

Some bikes can only achieve proper idle adjustment IF the bike has been properly warmed up first, 10 miles or so should do it.

Well it's been awhile, but the problem that I started this post with has seemed to have returned.

67 Atlas starts 1-3 kicks after sitting- and after I've run rhe #78 drill bit through the air/fuel hole to clean the junk out of them. Bike runs well for about 20 minutes or more, then will just die downshifting for a stop or idling at a stoplight. I'f I kick it quick, it fires back up, but I have to keep the reves above 1500 or it'll die out again.
Plugs checked and not wet, sparks when grounded against head. Bike just gets hot and quits.
Previous advice offered before was maybe my auto advance was sticking/not functioning, maybe the capacitators in the mag were in need of replacing.
How do I check if the auto advance is funtioning properly? Should iIreplace the mag capacitators regrdless? I've had the bike for a few years and don't know necessarily what's original and what's not.
Any advice appreciated...

If it wont idle and the jets are reasonably new and passages clear, an air leak?

How many miles on the carbs? Maybe the slides and/or needle are worn?

Try spraying WD40 around the carb/manifold and manifold/head interfaces when it is running to see if you get exhaust smoke or rev changes. To test external air leak

Do your mag points need cleaning?

wjrich said:

Well it's been awhile, but the problem that I started this post with has seemed to have returned.

How do I check if the auto advance is funtioning properly? Should iIreplace the mag capacitators regrdless? I've had the bike for a few years and don't know necessarily what's original and what's not.
Any advice appreciated...

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I do not think your problem is the AAU, but you can easily check that it is not sticking by removing the points cover on the magneto, and checking that the rubbing block can be advanced with the fingers, and that it returns on its own.

Dying hot is classically a bad capacitor in the magneto, but your report that you can restart immediately without waiting for a cool-down, seems to negate or rule out the capacitor ...... still makes me suspicious. Lay a plug against the head when the engine is cold, and get an assessment of how "snappy" the spark is. Then do the same when it quits hot. If the spark seems significantly weaker, I would blame the capacitor.

Slick

Check for rust in tank clogging the petcock filter...

Thanks all!
Tank has almost no visble rust, and when stopped after cutting out, i've pulled the fuel line and tested for flow- strong as it is at a pre-ride test. Carbs are relatively new- about 3 years- Amal concentrics which I clean out with the drill bit and carb cleaner before almost every ride. I also run the carbs dry at the end of a ride since the bike may sit for a week or 2 between rides. Jobs for this weekend (before I pull the outer cover to play with clutch as per other thread):
-check petcock filter
-Check gas cap vent
-check mag points/auto advance
-do the WD-40 leak test
Any thoughts of the replacement of the mag capacitators just for preventative value?