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So how the heck do you sync Mikuni Flat Slides?

  • Thread starter Thread starter zoo mob
  • Start date Start date
Z

zoo mob

Guest
I've synced carbs on SOHC4 Hondas before, but these look nothing like them an have no obvious vacuum ports.

IMG_2376.jpg


IMG_2374.jpg
 
zoo mob said:
So how the heck do you sync Mikuni Flat Slides?
Click to expand...

The same way you sync the stock carbs.
shrug2.gif


See that little screw that needs an allen wrench that is in the metal runner on the cylinder head?

That is where you put your adapters.

.
 
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Oh yeah, I should mention that these are on a stock 1980 GS1100E with stock exhaust. The bike came with these any idea which model they are?
 
Well, I'm feeling like a moron I guess. Can I be walked through the procedure in a sentence or two?
 
I have no experience with those carbs, but your first step is going to be to connect your vacuum gauges.

Morgan Carbtune is highly preferred.

.
 
Take the tops off one Carb is not adjustable the other three have adjusting screws and locknuts set those three to match the nonadjustable one. Not hard to do.
 
synq the slides? or the air flow?
slides are operated by the rod on top, check with mikuni on there site they might have exact documents for those, or set them all to open and close the same real easy like someone said already, if your talkin about carb flow there is a different style of flow tuner not the morgan multi hose style, i think those hose outlets are for air but thats all
are there hose outlets on all the carbs??
 
zoo mob said:
Well, I'm feeling like a moron I guess. Can I be walked through the procedure in a sentence or two?
Click to expand...

Hook up the gauges to the adapter tubes you install in the intake ports where the small allen screws are. Remove the carb tops. #3 is the "fixed" carb that doesn't move & you sync the other 3 carbs to it. The phillips screw on the top of each carb is the LOCK screw & the HEX nut is the adjuster. It takes very LITTLE adjustment on that nut to cause a BIG change in the sync. Turn the idle up to 2000-2500 rpm to sync. Call me at 714--356-7845 if you need help. Ray.
 
Thanks, this makes things abundantly clearer. It might be a couple of days, but I'll post back with results....and likely more questions.
 
As Ray alluded to in his post the adjusters are very sensitive with a little movement making a BIG change. The adjuster is not a threaded piece where you can fine tune it with a fraction of a turn. Instead it's a small offset cam that doesn't move much to make a change. In fact, the Mikuni manual I got from Sudco recommends doing a "bench synch" only on them. A bench synch is where you pull the carbs out and then use a small drill bit or piece of wire to manually set all of the slides to the same opening height. You adjust each carb (except #3 which is not adjustable) until you have a "slip fit" on the drill bit or wire much like you would when adjusting something with a feeler gauge. With the sensitivity of the adjusters, its a real tedious process.
 
I've done bench syncs on them that were SPOT ON & they ran like crap till I got the vacuum gauges on & synced them correctly. Ray.
 
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I guess you could use the vacuum ports on the engine or the carbs. The flatslide carbs have vacuum ports on them as well but you can't see them in your pics. They are on the engine side (duh!) of the carbs and have a little rubber cap on them. At least my RS36s do. Naturally they are difficult to access because synching an engine must be difficult. :-)
 
JimmyR said:
I guess you could use the vacuum ports on the engine or the carbs. The flatslide carbs have vacuum ports on them as well but you can't see them in your pics. They are on the engine side (duh!) of the carbs and have a little rubber cap on them. At least my RS36s do. Naturally they are difficult to access because synching an engine must be difficult. :-)
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thats what i was getting at as well ,those lines could be vent tubes that have tubes just ran to a canister or left open, so i coudnt say but mik site should
 
The float bowl vents are on the rear underneath the float bowls. They either have a thin rubbery hose hanging from them or are just left uncapped. They should not have a cap on them! They face down. The vacuum ports are facing straight up on the engine side of the carbs and should have a little cylindrical rubber cap held on with a wire loop.
 
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