always lean

[kevxs]

hi guys, starting to get ready to do some work on the bike for this season and I have a couple nagging problems.

1. headlight only works sometimes. i've done a clean of the connections in the headlight bucket but that didn't help, I'm assuming I have a bad ground somewhere but I dont know where to look.

2. running lean. this bike has always seemed to run lean, i've tired to colortune, adjusted floats, mixture screw nothing seems to help. my carb boots are only a couple years old so i dont think they are the problem but last year i did spray some carb cleaner around them to see if the engine would rev up and it didn't but it did start a small fire around the boots which luckly went out quickly.

i think this fire may be a clue to my lean condition but I could use some input. as always, any suggestions are appreciated

[crazy steve]

Well, a few questions for you...

When you say the headlight doesn't work, is it only the headlight, or do you have problems with the instrument lights too? For a overview of the wiring, look here: http://www.xs11.com/forum/showthread.php?t=35337
If the problem is just the headlight, then the problem will likely be found in the RLU or high/low beam switch and their connections.

'Running lean'. That's a rather broad statement, could you be more specific? Does the bike run badly, if so when/how, have you checked the plugs, do you have the correct jets installed, do you have OEM carbs, stock or non-stock exhaust, pods vs airbox, etc, etc....

[kevxs]

i actually forget if the problem was with the insturment lights as well or not, i haven't looked at it since last season. i think it was just the headlight. i know I did bypass the RLU last season trying to fix the problem but it made no difference. sometimes the headlight works, sometimes not.

when i say running lean i mean that the plugs are alot lighter than I would want and it also stubles at low RPM. when i hook up the colortune i cannot create a red flame no matter how far a turn the mixture screws in or out.

my bike is totally stock, no pods, no different exhaust or jetting.

[Schming]

You are actually looking to achieve a bunsen blue color with the colortune.

[kevxs]

yes i know that I want a blue flame, however i cannot get it rich enough to give me that colour. the directions for the colortune say to adjust the screw so that it turnes from orange to blue however all I can get is whitish blue no matter what I do with the mixture screws.

this leads me to believe that I have another issue at play other than the setting of my mixture screw, from what I understand the mixture screw is more for a final 'fine tuning' of the air/fuel mixture. I know I am running way lean, just cant figure out why.

I should also add that my clips in the carbs are in the middle position

[bikerphil]

yes i know that I want a blue flame, however i cannot get it rich enough to give me that colour. the directions for the colortune say to adjust the screw so that it turnes from orange to blue however all I can get is whitish blue no matter what I do with the mixture screws.

this leads me to believe that I have another issue at play other than the setting of my mixture screw, from what I understand the mixture screw is more for a final 'fine tuning' of the air/fuel mixture. I know I am running way lean, just cant figure out why.

If there is no change in color when turning the mixture screws, the tips might be broken off and stuck in the carb bodies. Take one all the way out and the tip should be pointy (78-79 carbs).

[kevxs]

the tips aren't broken off, I know because I've been there, done that and fixed it. the colour does change a little when I adjust the screws but it definitly does not go from orange to blue, more like light blue to really light blue.

[bikerphil]

Can you get orange flame when revving the bike above 4K? Did you replace your floats by any chance with the plastic ones and set them to the level recommended for the brass ones?

[kevxs]

still running the stock floats and I have them all set to spec (23.5 i think, its been awhile). i think it would turn orange if i revved it but i honestly can't say for sure, its been too long

[bikerphil]

Yep, you probably mean 25.5 which is correct, 23.5 would be too rich for the brass floats. I had a similar problem with another member's carbs a couple weeks ago. The #2 mixture screw wouldn't do anything and I thought it might be a broken tip. Not the case. What I had to end up doing was to blow compressed air thru the pilot circuit while holding my fingers over all the passage exits except for one at a time, making sure they were all clear. Sure enough, one passage was still clogged. It responded normally after all that. If you have any reason to believe the carbs may not be 100% clean, run some Seafoam in them, let them sit overnight, and clean them out again. If all else fails, try going up one size on the pilot jets.

[kevxs]

ok thanks Phil, that gives me somewhere to start. anyone have any idea why a fire would ignite when I sprayed carb cleaner on by carb boots?

[bikerphil]

Maybe arcing spark plug wire near by? You can also check for vacuum leaks with an unlit propane torch, a bit safer than spraying carb cleaner all over.

[Rasputin]

From what I know of the colortune if you can not go from orange to blue with the screw settings you are in the wrong jet range. If an orange color is not possible you need to go bigger jetting. The orange will appear as you richen your carbs. Once the orange color is achieved then you can lean out the mixture to get to your blue ranges. If you can not get the orange flame then you need to change jetting to be richer. If you can not achieve a bunson blue color then you are too rich on the jetting. If you have the paperwork that came with the colortune it is all explained there.

[Diskman01]

Just a quick thought here... What gas are you running? My 78 will run very lean on PB cheap gas. Has 10% ethanol blend and for some reason it runs really really lean (white plug tips). Shell non-ethanol 87octane will foul the plugs driving around town. too rich. I try to mix them a bit as I got tired of fiddling with my floats.

Maybe try a higher grade of gas so it burns slower? No ethanol if possible.

[natemoen]

First you need to check your floats and make sure.they are set right. 23mm if they are the plastic floats only and 25.7mm is they are the brass floats.