1980 750 LTD colortune results...and questions

Ok, today I finally had time to try my colortune out!

So I started with #1. Couldn't get the combustion to change orange unless I had the screw backed out something like 5 turns. So I moved to #2. Found it it wasn't even firing at idle! So I took the carbs off again for a clean, found a little bit of junk, but no smoking gun.
Re-installed carbs and continued on....I wasn't even able to get #2 to turn orange, but if I turned the screw out a bunch, I could get good blue color.

Switched sides and went to #4 and #3. Same results as #1. Got it to turn orange and back to blue... but at about 5 turns out again!

So I went to vaccuum synch and got everything purring like a kitten, but I had no room on the idle adjustment knob to lower the idle....so tomorrow I'm taking them off again to re-do my bench synch and investigate that #2 pilot system again.

My questions are: 1. The colortune worked well and the bike did improve on idle and off of idle, but my pilot screws are way further out than the usual 2 turns starting point. I have stock airbox and exhaust, but there is a few holes drilled around the center hole of the exhaust. This kinda sits ok with me, but it seems very odd to be so far turned out...but the color doesn't lie I guess.

2. I noticed when I got the idle tuned in and took the colortune out for my regular spark plug, the bike idled differently...has anyone else noticed this?

I didn't get to ride around or anything, but initial results seem good, except for the far turned out screws... I am thinking that maybe I should check my float heights too. I can garauntee my pilots are clean. Valves are also adjusted and I have good spark.

Well if I'm reading this correctly then the Colortune did exactly what it should have thus informing you the combustion chamber operations burning lean through ouot the adjustments....

Since it's occuring all 4 carbs, re-jett to rich pilot....

Are you followwing/accomplishing all 3 color tune adjustments?

What do your sparkies look like in using the plug charts?

OMR

Just in case.... Has the Color Tune & 3 Step adjustment charts plus a whole slew of carb info not to mention the Correct Spark Plug readng info....

kzrider.com/index.php?option=com_docman&...d&gid=461&Itemid=108

You are correct, it did tell me that #2 wasn't running right at all. Whats weird is that between turns 2 and 5, nothing changed, but it was clear cut transition between orange and blue flames.

See, I would think rejetting would be the answer, if I wasn't running almost complete stock.

Yes, once I did get step 1 set, the next two were fine. Step two did what was expected and step three was good too.

My spark plugs have a little tan color on the ceramic collar, while they seemed just barely a bit sooty on the rings. But I do ALOT of 60 mph riding, so maybe since I have a good handful of throttle for 99% of my riding it doesn't appear that lean? I'd say overall my plugs look good, but maybe a little lean.

I'm ok with having the screws that far backed out...if that seems reasonable though. I am really wondering what my fuel levels look like... This can have a dramatic effect, correct?

Spark base ring have a light carbon 360 around?
Ground strap 50/50?
Any speckles/particles on the ceramic (pre dentination)?

While riding... RPM held at 4000rpm (55-60mph) does she stutter as if running out of gas/missing?

Same rpm, let go of the throttle and let it snap back, pop out the exhaust?

Vacuum Sync to specification?

Off idle, does she hesitate /lag/lull before taking off?

Then 1-2 choices if above good...
1) leave at 5 turns and adjust accordingly...
Install some new plugs and take a 20 mile run...
Once cooled, pop the plugs out and inspect... If all good, no above symptoms then leave it alone...

2) Re-jet for Richer pilots... The re-Color Tune for adjustments & Sync...

5 turns may just be ok for your configuration.. If plugs aren't indicating burning too lean and no above symptoms, seems good to go....

OMR

my god man did you say speckles? :S :laugh:

Yup... Same speckles on your fore head.... Pre dentination, particle deposits, splotchy, patches... etc... :laugh:

carbon ring - yes, light carbon soot present.
ground strap is about 50/50.
no speckles that I noticed.

As for riding at 4k, no stutter. When cold I sometimes feel like it misses once in a while, but warm it doesn't miss a beat.

snap back from 4k gives no popping. Say, 7k and let it snap shut and it will pop once in a while.

I was vacuum synching after the colortune. I did get them to balance, but I had no way to lower my idle because I was at the end, so I was gonna pull them off, re-bench synch them in the middle of the idle adjustment screw and do it all again tomorrow.

Off idle (when cold) there is just a little hesitation. When warmed up, nothing.

I'll give it a shot tomorrow again and see where I am at. I think tonight after I did my vacuum synch that I could have re-done my colortune. That #2 not firing at all at 2 turns (all the others were firing at 2) and not even turning orange... something is not right there.

I'm just waiting for that picture of Red to say "You're a dumbass Andy" lol.

"Red to say "You're a dumbass Andy" "... :laugh: :laugh: :laugh:

Dave :woohoo:

.

Good point Tim...

Things to keep in mind...

You're only adjusting one carb at a time so on a ideally operating set of carbs you will here the idle smooth out... YES and it get's even better once all 4 carbs are accomplished....

As in this avi clip I did, the jetting was way on the rich side (jetting was NOT accomplished yet)... I took this on the very first motor build/carbs adjustments. This was #1 cylinder carb, had 3 more to go...

Listen closely as the flame turns more bunson blue then yellow.....


Then theres the issue you're having with carb #2... As you've noticed, something not right here on this one....

If you can't see the combustion color changes as your adjusting then Yup, something not working on that carb correctly...

Now once you get all the carbs working correctly, possibly re-jetted, Sync'd, the color tune adjustments completed then YES, you will have to readjust your throttle cables/idle slightly...

If you were that far out where no more adjustmnents can be made as it was, then my best guess it's been that way for who knows how long... So you re-adjust, no big deal...

And who said this tool sucks.... :whistle: ....
especially for carb trouble-shooting....

Once you get this all dialed in, you'll feel the difference on your ride.... Keep at it... Let us know how it turns out for ya...

OMR

Once I run to the store and get some clear tubing, I'm gonna solve this thing today. The more I think about it, #2 butterfly cannot be adjusted, with the exception of the main idle knob. SO, all other butterfly's are adjusted in reference to #2. So, the fact that I was out of adjustment makes me think that my pilots were dumping so much fuel in that even with the idle knob all the way out and butterflys closed I still had a high idle of 1.8k.

Would it be a possibility that each carb is a bit different and because the CV 34's have the pilot holes, transition holes, and then the main and secondary mains that if I tune my pilots according to Colortune's universal instructions I might just have too much fuel causing the high idle?

I'm not sure how familiar you are with the CV34's, but these transition holes are three small holes (bigger than the pilots) located right on the edge of the throttle butterfly. At idle, 2 of these three are covered by the butterfly. These transition holes are also fed by the same pilot system. So, coming from the pilot jet, it goes to these transition holes, then the pilot screw, then the pilot hole. So, maybe these carbs aren't the best example of the orange/bunsen blue transition for tuning? I did notice as I almost closed the screws the flame got much lighter blue, almost whitish/purple and started to miss. then there was the 6 or so turns of good lookin' blue flame (but no color change), but as I got richer it seemed to run better. (I noticed this colortune is good for color, but you can also see the rpm increase as the frequency of the light flash increases) But after an endless 6 or so turns, bam orange. So, I'll give it another shot today, but if I can't get any adjustment on idle after vaccumm synching, I might try splitting the difference between the orange/blue transition and the manual stated 2 turns out and see what happens!

I'm thinking my 550 might work differently (better) because there is no transition circuit between the mains and the pilot system, whereas the only way to adjust these transition holes on my 34's are to adjust the main idle knob.


I'll make sure today in my adventures to actually count the number of turns instead of estimating
I have to admit, this colortune is pretty cool tool. Even if I can't get it to work as a tuning tool, it's a helluva troubleshooting too at a minimum.