Colortune curiosity & poppita poppita pop poppita

[KA1J]

Stock jets, stock airbox, using a "dry cleaned" paper filter, Jardine Spaghetti

I'm used to using my carbtune & colortune on my XJ650 Maxim so when I used them on the XJ11 yesterday all went well with the carbtuning other than the Hitachi carbs use Philips head screws to adjust and their access to the screw head is much better than these Mikuni offer. using the colortune, the rod on #4 was very high and the rest were irregular to start, now all are jiggling within 1-3mm of each other, all at the same peaks & lows.

The colortuning did not go so well; When I installed the colortune, the engine ran badly, wanting to stall even though it idled beautifully after carbtuning. When I put the spark plug in it ran like an electric motor & when I put the colortune back in again it idled terribly and there was no orange I could get at any adjustment of the idle mixture screw. Not running properly with the colortune in place I wouldn't expect any color change to be valid.

I never have seen such a result with using the colortune on the 650, in fact it runs just about as well with the colortune in place as it does with the spark plug in there. Anyone else had this issue using a colortune?

Also

The bike now has 140 miles on it with the new rings and I'm following Motoman's break-in http://www.mototuneusa.com/break_in_secrets.htm (changed the oil/filter at 20 miles & will do the same at 200 miles) I have hardly used the brake and have done mostly full throttle & then zero throttle rarely going over 5k RPM. I've tried to emulate the racetrack scenario break-in procedure he described.

I have nice acceleration in that it goes from 55 to 70mph in a tad less than 3 seconds (counting one elephant, two elephant...) and then zero throttle till it is at 55 & then full throttle back to 70 & repeat. I've been driving on the interstate doing this for most of the 140 miles when there's nobody close behind. But when I decelerate I hear crackle/popping from the exhaust.

What causes this crackle popping? I've heard it on other bikes in the past.

Lastly, I gassed up just before the interstate & drove to Boston driving that accel/decel break-in method which is a killer for MPG and I gassed up in Boston; I had gone 92 miles using 2.73 gallons which is around 33.7 MPG which tells me when I drive like normal I ought to do pretty well.

Curious about the colortune and the crackling

[CatatonicBug]

I've never had that happen with the colortune plug. However, the colortune usually SOLVES the crackle-popping when it's working properly. Are you getting a good connection with the lead between the plug wire and the colortune plug? Make sure the inside of the colortune plug is clean and free of carbon traces. It may be shorting out.

[GLoweVA]

Silly question, but does the colortune plug have the right gap?
I'd think the XS11 coils need a certian gap to provide the right spark.

[DAVINCI]

Crackle-poppiti-pop on decel signals a lean mixture. You don't need the colortune to adjust the mixture. Leave the carbtune in place and adjust mixture for highest vacuum on each cylinder, then balance one more time. If it still pops on decel, turn mixture screws out 1/4 turn and test. Do that till the pop goes away. The jardine may be the culprit, causing you to need more fuel.

[KA1J]

I'm in Boston at my GF's place & don't have the plug with me to look for carbon traces inside (I did lend it out & several people used it in-between my last use & now...). I'll check it out & see if there is anything obvious that's wrong & if all looks good I'll try it on my 650 and if it acts the same I'll know it's in the plug.

Somewhere in lending it out the screw on cap part got lost & I'll have to find another loose cap to put on the extension. (I'm not using the original caps). I made a temp top "nut" out of aluminum foil so the colortune had a good connection.

I'm also using the green Dyna coils.

[KA1J]

Davinci, I can do that, thanks for the idea.

I just wish the placement on the adjustment balancing screws on the Mikunis made it easier to get to them. They're really hard to access, especially the center one.

[Axel]

early -late colortune

I recall a wise man telling me that there is a difference between early and late colortune plugs . More area inside the plug on the old ones make for a slight difference in displacement(?) and therefore runs rough . Newer ones make this less of a problem .
Anyway - It is always a chore colortuning my carbs and since I have them very close , I usually adjust according to sparkplug color and degree of popping with an eye on how blue my headers are getting over time .
So I also have a hard time with the XJ1100 but not impossible and it runs great after with the iridium plugs .
Also ,another wise man said it should take less than a minute - not to get too hung up on getting it exact .
I usually turn the screw out until I find the orange threshhold and come back about a quarter turn.
Somebody correct me if I'm confused.

[skids]

If I am understanding this, you set the carbs and then it started running badly after some break-in miles? Perhaps the breakin caused the vacuum to change as the rings set-in. If that is the case, resynch it and colortune it again. When I use it, I usually go with just off idle...maybe 1200 to 1500rpms.

Personally, I think you could warm-up the bike, install a new set of plugs, and check for color after about 4 or 5 minutes of subsequent running at the same rpms. I have done that with pretty good results. You might have to use a torch to burn off carbon between adjustment tests.

[KA1J]

Axel, On the XJ650 I get the colortune reading so there's a bit of dark blue & if I go a little more there's a lot of orange. I have it on the cusp so there's mostly dark blue with flecks of orange and it works great. I bought the colortune last spring from Len Chacal at XJbikes

Skids, I did 23 miles of Motoman's break-in and then changed the oil & filter. I took the bike for a two mile ride & came back and then adjusted the carbtuning so all rods were level. At this point the engine was idling nicely and the tach was not swinging but was holding steady. Once I was happy with the carbtune I got out the colortune and put it in & started up the engine & it ran terribly and the color in the colortune was bright/light blue. I ran the idle jet adjustment all the way in and all the way out to look for orange but the blue remained throughout. The bike stumbled quite a bit with the colortune in and I had to restart it maybe three times while I turned the adjustment screw/jet. As soon as I put the plug (Iridium) back in it again purred like a kitten. I never had anything like that experience with the colortune on the 650 Maxim.

I'll be back in CT tomorrow and will give the colortune a going over & will try it in the 650 & see if I have the same issue with it there.

Gotta tell you it was a real surprise to have this poor running/lack of change with adjustment because the colortune has been pure gold with the 650.

[natemoen]

I am having a somewhat similar issue with my colortune plug right now, no idea what is wrong.

[TADracer]

I'm also using the green Dyna coils.

Heres a possibility. Green Dyna coils are 3 ohm so, have you bypassed the balast resistor with these coils? With the resistor in the line it will give you a weak enough spark that the bike may run Ok with properly gapped plugs but the 'generic' gap on the color tune may not spark very well. Just a thought.

[natemoen]

Heres a possibility. Green Dyna coils are 3 ohm so, have you bypassed the balast resistor with these coils? With the resistor in the line it will give you a weak enough spark that the bike may run Ok with properly gapped plugs but the 'generic' gap on the color tune may not spark very well. Just a thought.

His XJ never had the ballast resistor. They ditched that thing for the '81 model year.

[81xsproject]

Yep, this is exactly what happened with my colortune experience. I threw mine away and started doing as Randy suggests, adjusting for the highest vacuum at a given RPM (you have to re-adjust the idle speed to keep it consistent). Like all other methods, it takes a few repetitions along with re-syncing.

[DAVINCI]

Yep, old school motors and old school methods go well together.

[natemoen]

Never heard this method until this thread. But I am going to do it now.