Colortune

[nzemke]

So I'm feeling kind of sheepish on this but I'm sitting at work trying to find out what size of colortune that I need for the XS. Is it the 10mm or the 14mm?? I have looked through the service manual and it doesn't say. And no one seems to say out right what size it is...but just that its what they used.

Thank you in advance for the answer!

[XJ Rob]

I'm pretty sure it's 14mm.

[BA80]

Never heard of a color tune working right on an XS with stock coils. An unnecessary waste of money in my opinion. It only works to adjust idle mixture anyway and it'll usually leave you running lean there.

[IanDMacDonald]

I have one of each size. I found it to be a waste of money. Best method to tune is plug chop & sync.

[nzemke]

I saw a post on another site where they were saying that you should get to the blue then push it right to where the yellow is starting to show and that works better then the "blue" because of the running lean part.

What did you find useless about it? I'm just trying to completely rule out using it.

[nzemke]

Never heard of a color tune working right on an XS with stock coils. An unnecessary waste of money in my opinion. It only works to adjust idle mixture anyway and it'll usually leave you running lean there.

Why not on the stock coils?

[natemoen]

I agree, they are not worth it. I bought one, used it a couple times and now it lives in a drawer in my toolbox.

It does not function like a real spark plug. Maybe if the electrode was actually exposed like a real spark plug it would work, but the electrode is buried way up inside the threads.

[BA80]

Stock coils have fairly weak spark from the git go and after 40 years, well you get the point. Whenever I've seen a Color Tune hooked to stock coils in most cases all it does is cause a misfire on whatever cylinder its on.

It'll work, to it's limited extent, on stronger after market coils but usually they don't last long and the ones that do are not cheap.

Best to just tune with vacuum gauges and plug chop I guess. (I've never found the need for the plug chop but then I've never tried to outguess the engineers)

[nzemke]

My big problem right now is that it is backfiring a lot and I know that the third carb is going to be off because when I got this bike the needle was broke off in there and the only way I could get it out was to drill it with the smallest possible drill bit I could buy...and that was still a smidge larger then the original hole...and not sure how that is going to affect it. If its making the popping noises that mean I need to turn them out a little more?

[BA80]

Heh heh...like I've always said, there are demons in that #3 carb.

Is it popping on idle or deceleration? Have you synced those carbs?

The size of the idle mixture screw shouldn't make a difference as long as it will still close off completely because the flow is adjustable i.e. the ADJUSTING SCREW. No, in most cases the adjustment won't be EXACTLY the same on all the carbs.

[nzemke]

I did sync them, and I'm getting my heaviest popping between 2.5k and 4k

[BA80]

Are you sure there are no holes in the slide diaphragms? Did you make sure those 3 little holes behind the throttle plates are clean? Does it go away if you ease up on the throttle?

[nzemke]

I had a second set of carbs (that was broken beyond repair when pulling brass) and went through them and grabbed the best looking of the 4.

I hate to have to do it but I guess I will have to pull the carbs again to check those holes. But they have looked pretty clean every time I have stared at them while bench setting the carbs before putting them back on.

And if I am thinking clearly it lets up a bit as I let off. and it gets a little sluggish when its doing that.

[BA80]

If it gets better with a wider throttle or less throttle it'll tell you where the problem is. Look at THIS and it'll give you a little insight into how things work. Ours has no "cutaway" but that's where those 3 holes come into play with the XS.

One other thing you might give a try, I don't know if you've done any checking on the pickup coil wires but the XS has a vacuum advance system just like cars did in 1980. The wires to the pickup coils that signal the tci to fire the coils will get bad from flexing over the years. LOOK HERE

You might unplug the hose that runs to the vacuum advance unit and to the #2 coil and see if that makes a difference.

[nzemke]

Thank you! Plenty there to read up on! And I will try undoing unseating the vacuum advance and see what happens.