Emulsion tubes on an SF

[IMIX]

Hello,
Finally got a good reason to take apart my carbs myself (bike shut down the other night, pouring gas out o the carbs).
I've found a few things that I suspect has been the cause of my horrible 25MPG. (besides the now obvious gunk I've cleaned out of the gas and air lines)
1st, one of the float posts is broken so the float tab doesn't stop it from sinking all the way down.
2nd, I discovered two different kinds of emulsion tubes in my carbs.
2 have 10 holes in them, the other 2 have 16.
the problem is, that the 2 with 16 holes are on carbs's 3 + 4.
I read in Blaine's carb faq that "Some models mixed two different needle jets having less holes on 2-3 and more holes on 1-4, probably to richen the mixture on the inner cylinders for better cooling."
so, just so I am straight on this:
Do I need to put the 16 hole emulsion tubes on carbs 1 + 4??

I want to do this right, this is my first time with ANY carburators open, and I really want good MPG and good performance.
Also, since I have these things open, would you suggest replacing all the jets with new ones?
these don't look so bad, no metal marring, and they've cleaned up decently.
Any help would be appreciated.
Thanks,
~Eric

[TopCatGr58]

Hey Eric,

The float post....if still there, can be repaired with JB Weld, it holds in fuel just fine once cured!

Like you found, would be okay to put the leaner emulsion tubes as you stated. The jets should be fine as long as they are thoroughly cleaned, ensuring that the small vent holes in their sides(pilot jets) are clear and not clogged, same for the emulsion tubes.

As for MPG, folks have stated that setting the floats a little higher/leaner can improve the mileage, but having a good vac. synch will contribute much to the mileage.

There have been posts on how to try to rejuvenate the solid metal float needles and seats, but might be easier to just get new ones. Ensure that your floats actually float, and don't have pinhole leaks.

Also inspect the vacuum slide rubber diaphragms for pinholes, can be repaired if found. Check the synch port caps on the intake manifolds for dry/hardening/cracking...can cause vacuum leaks. Don't forget to check the intake manifolds where they bolt to the head. Don't forget the inline fuel filters!
T.C.

[red bandit]

Don't forget to rinse your tank w/ petcocks off. 25 mpg is a bit low. If you twist on the throttle a lot don't expect to get over 30.

[TADracer]

Hey Eric,

I have a 79 'SF and you are right, the inboard carbs do have different emulsion tubes on the theory that the 2 & 3 cylinders do not get as much cooling from the wind.

If you are going through your carbs do not forget to check your float levels very carefully. Even a MM or two off can affect your mixture. Factory level for an SF should be set at 25.7MM from the gasket surface (not the gasket) with the floats resting on the springs in the needle valve. Its easy to make a gauge or two from some scrap sheet metal.

Also, as you already found out, removing the float pins can be damaging. When you are ready to install them again do not tap them all the way in, just push them in with your finger. The bowl will make them captive and they will stay in place just lightly pushed onto the holes so next time you need to remove them it will be easy.

Good luck!

[IMIX]

Thanks everyone for the great advice!
The diaphragm's are in surprisingly good shape. Is there anything I can put on the material to make them last? or just leave them be?

I just ordered a Morgan Carbtune pro vac sync with the colortune kit, so I can tune things in just right.

I will be paying close attention to the float setting. I realize now how badly the PO messed my bike up. I'm really excited to see her perform when I get everything tweaked just right.

I was really reluctant to tackle the carbs myself, but now that I have them out I realize its really no big deal. Like everything i guess..
I'm an electrical tech, so i KNOW how easy it is to screw things up you don't know about.

I have to say with my whole being:
THANKS to this site, and everyone here with their years of experience and love of these bikes.
I would have NEVER been able to restore my bike without XS11.com.
Other bike owners should be so lucky to have a phenomenal resource as this one.
again: THANK YOU ALL!!!!