Tuning Triple SU's

[satzman]

Anyone have a tech article source with visuals.? Would like to try to balance my SU's without going totally crazy. Thanks.

 

[LarryK]

First loosen linkages just enough to make sure that all the butterflies are closed. Then check stops to see if they are letting the butterflies close. Turn idle screws down and adjust up just enough to see the buttterfly move. Then check to see if the dampers raise up and down smoothly. Make sure oil levels are correct. Do you have a UNY-SYN tool, a sychronizer tool that uses the horn for air pressure so you can balance them. If not use a 3/8" vacuum hose and you will put hose in horn of carb and listen to the sound of each carb and turn adjustment until they sound same. Then readjust idle to set RPMs then tighten linkages and recheck. You can get a carb tuner book from XKS Unlimited or through Amazon. Not a hard job, just need a little patience. If you still have problems, squirt some wd-40 or something like it around butterfly shafts to make sure they are sealed properly.

 

[Marvin Gruber]

Only thing I could add to Larry's post is warm the engine up before using the UNY SYN tool. Not a bad job or hard to do.


Marv

 

[satzman]

thanks all. I'll give it a shot.

 

[Wizard]

Back before I could afford a UniSyn, I bought an SU tuning kit.

It was 3 pieces of bent up wire.
One for the center carb & two for the outer carbs.

They fit in the dash pots with the damper removed to show how far the needle was out of the jet..

The idea was to adjust the vacuum needle until all of the carbs raised at the same rate.

Gary.

 

[LarryK]

The kit works pretty well, but doesn't have the stability of the oil caps on. Use it in conjunction with a 3/8"or 5/16" vacuum hose and listen to each carb and make sure the sucking noise is the same ( like a stethescope only without the pad.) Listen and adjust with sight and sound, you will be amazed at what you can do. Also listen around the throttle shafts for leaks.
I started with this kit and still have it. Unisyn isn't much easier just a floating ball that is visible and good for the person that cannot hear differences in the carb intake hiss. Haynes has a book " Tuning SU Carburators " available at Barnes and Noble or Borders and thru Amazon.com.

 

[MGZT260]

Do the carbs have vacuum ports capped off? Invest in three identical brand vacuum gauges (pretty inexpensive at Harbor Freight) and connect them all at once - will be more accurate than UNI-SYN in my opinion - experience from balancing 4 carbs on a Kawasaki 900. (as well as numerous doubles on MG)