How to tune without a colortune ...

I need to tune some bikes: I have need to tune an XJ650, XJ550, and an XJ700X.

Colortunes are expensive @ something like $50 a pop, that is kind of out of the question, right now. Particularly since my unemployment got screwed up because I made the mistake of taking a 2.5 week temporary job. I am now two weeks behind and haven't a clue when they might get it fixed.

So, I have seen two other methods listed: the "plug chop" and temperature of the pipes. The question was posed as to the appropriate temperature fo the pipes in one thread I found, but I didn't find any answer to the question, although the thread did state the a regular thermometer didn't work as the reaction was too slow but that a laser thermometer should work fine. Still needed would be the appropriate value(s) for the bikes in question.

To do the plug chop test, I would first have to replace all the sparkplugs to get a clean sert, and hope that they didn't get contaminated so fast that I couldn't get a good burn. Nor do I really totally understand a plug chop.

Most people I have spoken to have never heard of a Colortune, not even the people at Jegs Performance Auto, so for the rest of the world, how do they get this set without the colortune? I have trouble believing that normal shops do the chop test.

 

On the 650 - 750 Hitachi, the initial Pilot screw setting is 2 1/2 to 2 3/4 from lightly seated. Other carbs may have a different initial setting. From this initial setting, you can do the "ear" and "tach" method, slowly screw #1 in until you hear the engine consistently miss, then out until the tach returns to it's highest idle, but not more than 1/2 to 3/4 turn.

Repeat 1 thru 4 at least twice. This takes practice, patience, and a good ear. Record the exact angle position of the 4 screws as your initial set.

Drive it at lower neighborhood speeds and 40 MPH back road speeds with a light touch on the throttle. After 15 minutes, read the plugs, adjust the 4 screws a SMALL amount, recording the amount you adjusted them. Write down every change, keep at it. If you have a "bog then go" you are too lean, turn the screws out a little. Eventually you will just be tweaking one carb.

 

That's a real pain, considering that each cycle also means removing the fuel tank so you can adjust. I have a hard time believing that is what the "pros" do ... and since all the pro's I have spoken with have never heard of the Colortune.

 

Get a screwdriver bit that will fit in the pilot screw holes. One of the ones you put in a magnetic tip exchange screwdriver (2 inch long bit). Or a short sewing machine screwdriver.

You should be able to turn the screws without taking anything off the bike then, you may have to carry some sort of gloves so you don't burn yourself on a hot engine, but it's the easiest way i've found to change screw settings on the road while tuning.

 

I've found the easiest way to do a colourtune and synch is to remove the fuel tank, place it on a table (slightly higher than the bike) and run a longer fuel line to the inline fuel filter. It takes me no longer than a minute to rig this up.

Block off the vacuum tube on # 2 carb (or wherever you connect the vacuum line to) and run on prime for the duration.

Simple task then to reach the mixture screws and synch screws without the risk of damaging the heads of those mixture screws.

 

If I were you I would buy the colortune and do your three (4 counting the X) bikes. you would be real good at it by then. find some friends on here or some neighbors or something and tune their bikes for them with it. Charge them whatever you think is fair, maybe 25 bucks. If you do just two bikes for that price then you will be even, any more and you will actually be making money.

 

Doing a bit of research, I found that there is a "12mm adapter" ... do I understand correctly that this would allow me to use the 14mm colortune in both 12mm and 14mm engines?

 

Mike

It's my understanding the Colourtune is available in 12mm and 14mm sizes. I could be wrong but I don't think there are "adapters" as such.

I bought mine (actually have two) in UK last year for GBP25 each.

edited: to say I just checked the website where I bought mine and they are now GBP35!

 

I have heard of the adapter. never seen it, but have heard of it.

 

There are adapters: http://www.gunson.co.uk/tools.aspx?cat=673