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New Weber 38/38 Carb No Start

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3.6K views 3 replies 2 participants last post by  Sarge  
#1 ·
Just installed a Weber 38/38 with elec choke today. On the first cold start to warm up, had it running pretty decent. Got cocky and proceeded to adjust idle mixture. Seems the 38/38 has two idle mixture screws (Or am I wrong), one on the passenger side of carb and one on the drivers side at the base. Fiddled with the passenger side one with a little bit of success. Went to the drivers side one. As soon as I moved the screw, the vehicle stalled, and will not start again. The only directions I received with the carb are for a 32/36. I have one of those on another vehicle, and have had no problems adjusting it. So basically does the 38/38 have two idle mixture screws as it looks like to me? What do I need to do to get the vehicle stared again?
 
#2 ·
Found out why it would'nt start, the ign fuse was blown. Can't keep it running now. Idle mixtures screws, if they are both idle mixture screws, may be way out of whack. What is the starting point for them? Engine is not cold and not hot (from messing with it), outside temp is 75 degrees, is engine temp a problem to begin with?
 
#4 ·
Check the choke wire, make sure it's not shorted and supplies +12v to the choke element when the key is in the "on" position. Starting point on the idle mix screws (yes, both of them) is 1.5 turns out unless it's one of mine. Adjust one out a bit and see if the engine speed changes up or down. Both screws must be adjusted evenly and balanced to achieve proper throttle response off-idle. They can be balanced by counting the number of turns from stop , just lightly bottom them, do not force them into the seats hard . Base idle mix adjustments are made with the engine at full temp and the choke open , engine idle should be below 600 or so rpm to assure the throttle blades are closed. Adjust the mix for the best overall smoothness and rpm's, once adjusted the mix should not have to be re-adjusted to achieve proper idle speed (750-800rpms). If you try to raise the idle speed and the engine falls flat it is likely the idle jets are too small. Most 38DGAS are built with 45-50 idle jets , most Suzuki's require 60-65's for proper off-idle respnse due to the shape of the intake plenum. Also, the intake really should be flowed for the carb to work properly otherwise it is breathing through a serious restriction.
Sarge