Author Topic: Setting up carbs (Read 3053 times)

bandit4 · « **on:** September 21, 2005, 07:18:24 AM »

Hi i've had a search and didn't find what i was looking for, i'm not sure if anyone remembers but my brothers got a bandit 400, not running. So we stripped and cleaned the carbs and found the previous owner's mechanical skills were nothing short of shocking. Some of the springs that pass through the diaphrams were kinked, one of the mixture screws was completely screwed in, so damn tight but the others were fine. We've now got it running but it idles quite high. adjusting the idle screw doesn't help much as you adjust it down to idling about 1500 revs (is that about right?) and then rev the engine and it goes bk to idling at 3000. We're thinking the mixture screws need setting up, what is the default setting so we have a base to start tuning on? Is there a defualt/factory setting i.e. 2 turns out for the mixture screws? thanks for any help guys, i'll post a picture soon of the bike.

PitterB4 · « **Reply #1 on:** September 21, 2005, 12:15:28 PM »

I'll bet the synch is WAY out of whack, too! You do need to get your mixture screws set correctly first though. I don't have my manual in front of me but I think the stock setting is 1.75 turns out.

b4cruz · « **Reply #2 on:** September 21, 2005, 01:39:02 PM »

mine was sensative
did my valves and it did exactly what you described with the idle
you gotta put the screws to the stock setting
try to get the idle as close to 1500 with the airbox & filter on
then clean & ballance those carbs
my adjustments were so tiny
but when i was done it, it was DONE
been a few months now and it starts everytime and runs perfect
but its always happiest when its ridden often and at the higher RPMs!

PitterB4 · « **Reply #3 on:** September 21, 2005, 01:43:24 PM »

Quote from: "b4cruz"

...but its always happiest when its ridden often and at the higher RPMs!

Aren't you happiest when it's ridden at the higher RPMs???

Maniac · « **Reply #4 on:** September 21, 2005, 01:46:23 PM »

Quote from: "PitterB4"

Quote from: "b4cruz"
...but its always happiest when its ridden often and at the higher RPMs!

Aren't you happiest when it's ridden at the higher RPMs???

The bike's happy, we're happy, everyone's happy!

b4cruz · « **Reply #5 on:** September 21, 2005, 03:57:12 PM »

YES

!

I only have the stock pipes
but even still as long as I have ear plugs
high RPMS are like a coupon for crack in the ghetto for me and the BIKE!
As long as the bike is revving and the pilot is skilled
our b4s will keep up with most anything out there
got the bike still working on the skilled part

b4cruz · « **Reply #6 on:** September 21, 2005, 04:00:38 PM »

when you are tuning the bike it will also raise RPMs a good three times before its up to running temperature. This is how I can tell my bike is ready to ride. I don't like using choke unless it doesn't start the first time. I just use my idle screw slowly turn it down everytime the RPM does the jump. You may want to warm up the bike before you do any adjustments.
b4s are cold blooded

B4s hate

carbs out of sync
wimpy old o-rings
cheap batteries
low rpms
sitting for over 1 week
the original fork springs and rear shock they came with
and not being warmed up a good 5-8 minutes till idle is steady at 1500