Diving into carbs - first question!!

[11Rider]

Hi my friends. I posted a week or so ago about my 79 Special running bad off idle up to 3k rpm. I just started taking the carbs apart and the first thing I noticed was that everything looks REALLY clean so far. Also, I noticed that the needles has a springy orientation toward the engine. Now, if my memory serves me correctly on my other bikes the needles were to spring toward the airbox. Could anyone verify which way is correct?

Also, on the 79 Special I had in 1979, I raised the jet needles one notch and it made the bike run better overall. I do believe I will have to do something with my low rpm circuit, but should I raise the jet needles a notch while I'm in there as well? Thank you very much.

[TopCatGr58]

Hey Rider,

I think you may be confusing some of us? The needles you are speaking of are probably the vacuum slide needles that slide down into the emulsion tubes aka main jet nozzle. They are mounted with a spring, but I don't ever recall anyone specifically stating that they needed to be tensed/flexed towards the engine side vs. the airbox side?

Glad to hear things are appearing clean, but you will want to make sure you remove the pilot JET as well as the main jet nozzle/emulsion tube, very fine ports there that can get clogged with fuel/varnish easily. Also the pilot/idle jet SCREW on the top front of the carb body. Need to spritz cleaner into the pilot jet tower, ports in the inlet bell, pilot jet screw tower, etc., and ensure it sprays thru to the little ports on the intake side inside the carb throat. Don't forget to test the float bowl jet to make sure it's open.

Raising the slide needle richens things up but moreso for the mid/upper range for when you're getting onto the throttle and into the mains more, vs. the pilot circuit. To fatten up the low rpm range without necessarily over richening up the mid/upper range, folks usually turn the pilot jet SCREWS out a 1/2 turn or so, test, and turn again. However, it's stated that if more than 3 turns out you should go to the next larger pilot jet size.

Also, lots of tuning is trial and error/test! Remember, these carbs are now 30 years old, the slide springs are also, and some folks reported that they actually had gotten weak and perhaps the slide was rising too quickly flooding the carbs before the engine could handle the load. Some stretched their springs, others got NEW ones, etc., and reported that their throttle response became better....YMMV!

Don't know if you have any MODS..intake or exhaust on your current bike which could also affect tuning processes. Best to place that info in your SIGNATURE so it's shown with every post you make.
T.C.

[skids]

My 78's tend to slide in the emusion tubes towards the engine. They are not centered. There is only one way to put them back together so don't worry.

[11Rider]

OK guys thanks. I probably didn't describe it well, but the needle that comes down out of the bottom of the slide is mounted in such a way that there is a small spring on top of it and a little nub on the plastic piece above it. This will give a little tilt/bias on the needle. I'm glad to hear it's supposed to tilt toward the engine side. Thank you

[11Rider]

Oh also, is it worth taking the pilot jet screws out and spritzing carb or brake cleaner in them in an effort to clean up the low RPM hesitation and avoid completely dismantling the carbs or would this just be a waste of time?

[DGXSER]

Honestly, once the carbs are out of the bike, I would definitely take the time and effort to completely strip and clean them. Find the "Carb cleaning 101" thread, follow it.

Trying to do part of the job is why the "triple clean" term was created

[11Rider]

You're right. I've already started the process anyway so I'll finish getting them out tomorrow. Thank you