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Hooking up SR400 Carb

Discussion in 'Technical and Troubleshooting Torque' started by mattb, Jan 26, 2010.

  1. #1 mattb, Jan 26, 2010
    Last edited by a moderator: Jul 13, 2015
    QuarterWit has loaned me his VM32 SR400 carb to try to get the settings worked out to run with the SR400 engine I installed in my '78 500 a few months ago. The bike's been off the road all this time, aside from a test-run which showed the original 500 VM34 was way out jetting-wise. Anyway, I'm unsure about a couple of hoses and spigots.

    Here's a left side view. You can see a hose running from the 'manifold'. It can touch but not properly reach the fuel tap. You can also see a spigot to the right or rear of the carb.

    Here's a right side view. You can see, to the left, a hose, which is quite long - it could easily reach the fuel tap suction spigot. Just to the right of it is another spigot.

    Obviously one of these hoses goes to the suction at the fuel tap. But where does the other go? What of those two spigots? Intelligent guesses welcome. There's an electrical thing coming out of the carb too, but I'll just pretend it doesn't exist.

    Here's the bike taken at 2am as the drugs wore off. Unregistered, unridden for just short of a year, and ready to hit the open plains and explode my mind into outer space as I reach for the stars and embrace the Nightrider.


    Tomorrow, when I get these hoses sorted, I'll kick her over for the first time in a while. Sweet Mother of Mercy, I long for that thump after living life with a boring four cylinder hum. The bank gave me this thing called a credit card: it gives you free money. This baby will ride legally again, without being hassled by the pigs! I'm thinking of taking it in this freakin' crazy direction [media=youtube]YswkF-d2VZ8[/media] 'cause I've had it with The Man! A bit of bent pipe and a fishtail bolt-on's gonna get me bent! Way gone!
  2. The hose coming out of the 'manifold' either needs to go to the vacuum side of the fuel tap or be blocked off. The other stuff might be involved with emission control. I'd suggest looking at a standard SR 400 to get some clues. The problem with just deleting emission stuff is that you may end up with other problems (flat spots?) as the carb will not be working as designed. I'd be very surprised if a 500 carb in good condition would need much adjustment to work with the 400.
  3. The electrical thing .... just attach it to either the battery positive or the earth. Or save time and attach it to both. It's not like anything is likely to go wrong.