Black plugs???

[drooker56]

I had a terrible mis after phsychoreefer came over to help sync my carbs. I finally put in some new plugs the others were terribly black (sooty). The mis was gone and she ran like never before. After that short ride I came home let her cool and pulled the new plugs and they were already black. I am having trouble understanding the tech tip on this. does this mean my mixture is rich or lean and which way do i go with my screws or does this mean something entirely different with a different fix. I am running pods and my screws are about 2 1/2 out, or so I think. Any help would be much appreciated.

[drooker56]

please don't think I am an idiot I am just sick of being counterproductive with my bike maintinence. It seems I do everything 3 times before I get it right. I think I am losing my mind in my old age and hey why guess when you guys are all there to help fools like me?

[dbeardslee]

Black plugs are an indication of a rich condition. I find a colortune plug indispensable when setting carbs. It lets you see what's actually going on in the combustion chamber, and IMHO makes it much easier to get them set correctly. 2.5 turns out seems a bit much, but without knowing the particulars of your setup it's hard to say. It's usually a good idea to put the particulars of your setup in your signature (modifications, jetting, etc.) as modifications to exhaust and intake will affect jetting, and that will affect plug condition. You can try turning the screws in (1/2 turn at a time, then run her and check 'em), and that might solve the problem. What really has a significant affect on plug color is float height. If turning the screws in doesn't solve the problem, you might try raising your floats (when they're upside down on the bench) 1-2mm. To really do it right you also need to resync after making changes to your carbs. The sync should always be the last thing you do in a tune up.

[Ken Talbot]

Along with black plugs, what sort of mileage are you getting from your bike? If you are not well up towards the 30 - 40 mpg that well set-up carbs should deliver, you might want to start like dbeardslee suggests with your floats.

I put up with very black plugs and poor mileage for way too long. By moving the floats 2mm "leaner" (i.e. higher when the bank is upside down on a bench), my plugs came back to a good colour, and my mileage increased immediately by 10 mpg.

Start there, resync, colortune or 'colortune by ear', then see how the plugs look and what the mileage is.

[drooker56]

I will try both the floats and going to two turns out. One thing I have noticed is the pilot scre on carb 4 (left one) will not go in as the others do. when its tight the spring is barely compressed. I checked it out and there is no obstruction. Why could this be? Has anyone heard of this? I will pull the carbs today. what about float level makes this occur?

[dbeardslee]

Over time the springs on the mixture screws may have gotten weak. George fix sells some very complete rebuild kits that include new mixture screws and springs. You might also check to make sure the tip isn't broken off on that mixture screw. When you turn those screws in never go in farther than "lightly seated". More than that and your asking for trouble - broken tips can be a PITA to remove.

The floats control the fuel level inside the bowls, which in turn regulates how much fuel is available to the internal fuel circuits. It affects the leanness/richness across the entire rpm range.

Also, if you don't have the tools, here's something you might want to think about - Carbtune/Colortune Offer. If you order the kit, you'll need the 14mm colortune.

[drooker56]

I put rebuild kits in, the spring and needle are in perfect shape and ther is no tip stuck or at least I cannot see one, there is a clear hole straight through.

[dbeardslee]

Drooker - Do you have mods to your intake or exhaust, or are you all stock? Do you know what your jetting is? If you're all stock, with the 137.5 mains and 42.5 pilots, I would be surprised if your mixture screws needed to be more than 1.5-2 turns out from lightly seated. The reason I like to use the colortune to adjust my mixtures is because it shows you what's going on. Rarely is the same number of turns going to have the same affect on all carbs. Slight differences in the shape of the mixture screws, or slight differences in the draw from the pistons will affect where the screws need to be. The end result is, that when properly adjusted, you will probably have a different number of turns on every carb. Some people use an auxiliary tach to adjust them (the stock tach isn't accurate enough), and some people can adjust them by ear. Personally I've never been able to get acceptable results from either of those methods, but the colortune works well for me.

[drooker56]

your right, I think I need a colortune. It will probobly be a while until i can swing one but i will let you know what kind of results I get. I will have to order one as I cannot find anyone locally who sells them.

[psycoreefer]

I've had good luck tuning by ear, maybe not as good as a color tune but my plugs don't turn black, read the tech tip and give it a try. You'll definatly want to check what jets you've got and where your float level is set if you've got the carbs off though, hard to make adjustments if you don't know where your starting.

[drooker56]

everything on my setup is stock except for pod filters and 4 into 2 straight pipes. Could this float level thing be why my idle hangs high at stops?

Brian, I can't tell a damn thing by ear as you know my bike is just too damn loud to notice slight variations. We need to get together soon and ride, I will let you know when we have a sitter next.

[dbeardslee]

Drooker - With pods and the 4/2 straight pipes your jetting is probably lean if the jets are still stock. Take a look in the tech tips under "Jetting Recommendations" and it will give you a pretty good idea what you need. Why, if it's lean, are my plugs black, you ask. Don't know why, but I do know that Betsy would foul plugs in no time flat until I got the jetting right and the carbs properly adjusted. The jetting is definitely the first thing to address - if it isn't right you're whistling in the wind trying to adjust them.

[TopCatGr58]

I put rebuild kits in, the spring and needle are in perfect shape and ther is no tip stuck or at least I cannot see one, there is a clear hole straight through.

Hey Drooker,

Where did you get your kits from?? eBay?? And were they labelled K&L?? There have been reports and anectdotal stories about folks either getting the wrong kits with the wrong style pilot jets which cause severe richness. When those same folks put in either real Mikuni jets, or their cleaned up old ones, then the bikes ran right again!?

Also, your 79 should have had caps/screws over the pilot jet chamber, because the pilots draw their fuel from the MAIN JET tower via a small tunnel between the two towers. BUT if you don't have the Pilot jet towers capped, then they draw fuel both thru the tunnel and directly from the float bowl causing overly rich condition!

AHA...also what brand of INDY PODS are you running...EMGO perhaps??? Are they cone shaped like K&N? These pods are also known to cause problems because of a prominent mounting lip on the inside that restricts airflow thru the ports in the inlet bell, again causing overly rich condition!?
T.C.

[psycoreefer]

If you need pilot jets let me know, I have an extra set i got while trying to sort out my carbs, I also have a set 2 sizes larger then stock as well as some one size up mains. I've got a few other carb parts around too, stock emulsion tubes, K&L needles, ask me before you go buy something....
As for tuning the idle mix, I'd be happy to give it a go for you, bring the bike over sometime and we can see what we can do. I know it's loud but I don't care about my neighbors, the ones on either side are renters and the only other one that speaks english I've already had to call the cops on so they can deal with loud.....

[foreda]

Black Plugs

I know there are a lot of people here that can tune an engine by ear. I am not one of these people since I am about half deaf. I bought the ColorTune plug to help me set air/ fuel mixture. I was having similar problems trying to sync a set of carbs and get the air/fuel mixture right using the usual rpm rise/ fall method described in several posts on this site. After receiving the colortune plug, I found that no matter where I set the mixture screws, the color would never change. This proved to me that there was a problem with the kits that I was using. After cleaning and reinstalling the original jets and needles, I was able to set the mixture close to perfect. The symptoms that I was having with these kits were hanging idle, and black plugs.