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Discussion Starter · #1 ·
Will the air bypass screws make a difference?
Got my ST2 running:), custom 2-1 exhaust CF can, Ferrachi eprom[fbf150?], It seemed good at first but then seemed to get rich after 50 or so miles, it idled at about 800 rpm.
I adjusted the trim clockwise[one site said that is leaner, another says that is richer?] It seems to have leaned it out, now the idle is inconsistent. 1200 rpm sometimes, 2100 rpm other times. If I just pull in clutch when slowing, it seems to hang at 2000-2100. If I run it down to 1400 before pulling in the clutch, it will stay idling at 1200-1400.
Tps has been adjusted, carbs synced, air screws about 3 turns out.
Setting the sag? Full of fuel? Empty? About 45lbs. difference.:confused:
0-10mm free sag, 20-30mm laden sag, Is that 20-30 total or 10 + 20-30, so 40mm total laden sag for cruising. Another site says 35% of travel[about 40-45mm] for laden sag.
One site says start with compresion damping full off, another says start with comp. full on? Go figure.:think:
 

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Blame the universe not the tank!
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3,234 Posts
3 turns out on the air screw seems a lot. I don't know about that year bike though.
 

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air screws about 3 turns out.
That does seem like a lot. I can't tell from your post if you’re running lean or rich now at idle. I'll assume lean. Try turning those screws in some. It's not like the old carb days where you run the pilots out 1.5 to 3 turns to start. I guess it is kind of like that, as they effect idle and just off idle throttle, but 3 turns is a lot for these air bleeds. If you have them out that much, I wonder if your idle set screw is set correctly. I think I have one of mine all the way in with the other turned out just enough to have a balanced TB at idle (I use a Twin Max balancer). Admittedly, I have no idea what my CO is at idle, but the bike runs perfect, so I assume it's close! If you're running rich at idle with them wound out that much, I'd say something else is way out. Fall back and start at the TPS setting again to be sure everything is correct. The procedure I have used to do this has you winding the air bleeds all the way in and idle set screw all the way out (butterflies fully closed) to set the TPS. Next you set coarse idle with the set screw; fine tuning with the air bleeds for a balanced TB at idle. Then, of course, TB balance at part throttle (air bleeds have no effect here) to balance with the actual TB balance screw. My understanding is the air bleeds only have an effect at idle to set a combination of correct CO, proper idle speed and TB balance.
 
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