Color tune

Good to know this. My booklet seems ancient by comparison and only deals with idling, but the unit looks identical.

Don't buy it. It is useless, frankly unless you have a dyno. I bought (and still have) one about 25 years ago. Unless you can watch when the engine is under load, you will only optimize your idle mixture.

montelatici said:

Don't buy it. It is useless, frankly unless you have a dyno. I bought (and still have) one about 25 years ago. Unless you can watch when the engine is under load, you will only optimize your idle mixture.

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I agree, but you can't knock it for idle mixture. Useless for anything else. Only reason I have used it for the idle is because I already had one so it didn't cost me anything.

I have one, but my Norton likes a bit more rich mix than the "ideal" spot, so the tool is only a guide for the starting point. On my brother's inline 4 ricer the color tune is the only way to get 4 cylinders set up right. It really does work.

Be aware that the tool comes with a plastic shroud tube for viewing the flame, and if you let the engine get too hot the tube will melt into a gooey mess. DAMHIK.

I use mine just to set up the idle mixture but I find it prefers to be a bit richer than the Colortune suggests. A problem I'm having is that after running it for a few minutes the spark starts to track across the (quartz?) window and it has to be allowed to cool down before it will work again.

Back in the 70's I had an early model Colortune before the specific bike Colortune was introduced. It looked more like a regular spark plug where what is normally white insulator was all clear material. One day when using it to set up my Dommie Monobloc there was a loud bang and the clear part of the plug shot past my ear. Since then I've always been reluctant to raise the revs above idle when Colortuning!

For last decade on other lists I've learned that Color tunes are at best usless and at worse give wrong reading. Can not be used to tune but for idle mix. By gosh and by golly trail and error if only way to go on our old bikes. Even Comstock EFI don't use no stinking Color tunes which likely can't read right with new lean clean burn gasoline. Only extra expensive wide band O2 sensors give useful reading outside of WOT. If nit picking on old school plug chops, even that really requires cutting plug open to see base of porcelain.

A side note on heat range selection, thermal stain should show up on plug side of the electrode bend. Some soot on plug thread rim flat is desirable finding.

hobot

Colour tunes are a complete waste of time! The old plug chop is infact a better indication. Unless you can see what's going on under all throttle positions . Simply reving the engine on its stand is no good. Engine load and slide openings will produce rich and weak mixtures, but because these are short you donot notice them. As long as the overall effect is average "correct" .

batrider said:

"Bunsen blue" they call it.

Orange is too rich. Just like a Bunsen burner.

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