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Air Screw
- Thread starter Gpaws1968
- Start date
See red circles
From the factory they are capped with a pushed in brass plug.
From the factory they are capped with a pushed in brass plug.
Gpaws1968
XS650 Enthusiast
So I can't adjust it?
Gpaws1968
XS650 Enthusiast
JJames
XS650 Addict
You can and probably should adjust it. They were set very lean and capped at the factory for emissions. If the caps have not been removed already, not too difficult to drill/pop them out. You will want to remove the screws plus spring washer and O-rings in order to clean this circuit. First, before removing, gently turn the screws clockwise by half turns, counting as you go. Stop as you feel resistance as tightening them completely will damage the tips and their ability to meter mixture accurately. This will give you a baseline setting. When reassembling, return screws to baseline and then adjust. Clockwise to lean. Counterclockwise to richen. Have fun.
Gpaws1968
XS650 Enthusiast
I thought I was going crazy yesterday when I couldn't find the screw, thank you
Gpaws1968
XS650 Enthusiast
How many turns out is the default, I'm thinking 10 half turns.
I am guessing as my bike is older, but perhaps 1.5 full turns out from lightly seated. A guru will correct me
The BS34s were pretty E.P.A. strangled so like more. On a stock bike, somewhere in the 3 to 3.5 turns out range is usually needed. If you've modded the bike and changed the jetting, a bit less will work. On my '83 with one size larger pilots and one size smaller air jets, the screws are set at about 2.5 turns out.
Gpaws1968
XS650 Enthusiast
It is hard to keep running when cold, the slightest move of the throttle and it dies and when you do get it to rev it backfires, when warmed up it runs great.
You need a richer mix when the engine is cold, that's what the choke is for. If it's doing this with the choke on then maybe the chokes aren't working, or working fully. Maybe the choke feed jets in the float bowls are plugged or partially plugged. Here's how to check them .....
Gpaws1968
XS650 Enthusiast
Yeah, I have the chock fully out, then when I can rev it I go halfway with the chock then when I start riding it, I push the choke all the way in
Gpaws1968
XS650 Enthusiast
So, I'm back
I turned the screws out 4 turns and it starts better when cold but has a dead spot at low revs and intermittent backfire, I'm getting a 90-degree screwdriver so will start tuning.
I turned the screws out 4 turns and it starts better when cold but has a dead spot at low revs and intermittent backfire, I'm getting a 90-degree screwdriver so will start tuning.
JJames
XS650 Addict
I found this to be useful for adjusting bs34 idle screws. Craftsman 41380. It will fit 1/4" ratchet but I've always used it on its own. Drop the bit down the hole and turn slowly until the blade falls into the screw slot. You can maintain downward pressure with a finger. A line across the top and side represent 0 or 12 o' clock. Easy to read and make precise adjustments.
