Author Topic: Carb tuning,..how exactly? (Read 4171 times)

Farre · « **on:** March 26, 2006, 07:10:21 AM »

Hi,
I've been looking into changing the settings on the B4 carbs. To me, which practically zilch experience, it looks like an intangible mess of screws and needles.
I'm pretty sure my carbs are not doing what they're supposed to do: much too lean and not correctly set relative to the others (middle cylinders should run cooler than outer cyl's). In idle you can hear the rhythm changing..

Now i want to get this straight of what one needs to do. Please correct me if i miss anything or say something wrong.
-First one must 'read the plugs' (on a hot engine) in low rpm's (pilot jets), high rpm's (main jet).
-according to the readings one must screw in/out the mixture screws, located on the float bowls for adjusting the condition in the low rpm's
-one must adjust the height of the main jet needle in the high rpm's. This is done by changing the clip position and/or shimming the needle.

Is this correct?
So my neighbours will see me race up and down the street a lot of times for reading the plugs, i take it this cannot be done in neutral?

I must say i've learned already a lot from this Board, but experience can only come when you do it yourself..

Farre · « **Reply #1 on:** March 26, 2006, 09:47:09 AM »

about the shims, anyplace where we can get them, besides from the US or Canada? they should be easily available, but i've been into some shops and didn't find exactly something that might fit the picture...

gsxr400 racer · « **Reply #2 on:** March 26, 2006, 11:54:52 AM »

got a pipe , slip on , modified air box, different air filter(k&n). buy a jet kit
shims for clips radio shack (take a needle out take it to the local hardware and and buy a washer the same thickness as the clip and same distance around)
fuel screw _ idle to 1/8 throttle
pilot jet- off idle to 1/4 throttle
neddle- 1/4 to 3/4 throttle
maIN JET-1/2- WFO(WIDE FRICKEN OPEN)

Red01 · « **Reply #3 on:** March 26, 2006, 01:36:26 PM »

They probably don't have Radio Shack stores in Belguim, and if your hardware stores don't carry anything that small, try a shop that deals in electronics. Washers that small are common in that sort of stuff.

gsxr400 racer · « **Reply #4 on:** March 26, 2006, 02:53:55 PM »

tHATS WHAT I WAS GETTING AT BY RADIO SHACK, But well explained thanks Big Red!

Farre · « **Reply #5 on:** March 26, 2006, 05:06:09 PM »

i didn't make any other mistake?

I didn't know all those were adjustable!
I found in the manual that the pilot screw base setting is 1 1/2 turn back out.
but the three others are question marks.. anybody know a setting that should be safe for these?

About the middle cylinder being cooler, does this mean the settings of all four should be a little richer?

FYI, i don't have anything out of the ordinary on my bike, no slip-on, no K&N filter, i just want it to run smoother

Krautwagen · « **Reply #6 on:** March 26, 2006, 07:00:17 PM »

http://www.factorypro.com/tech/carbtune,CV,high_rpm_engines.html

gsxr400 racer · « **Reply #7 on:** March 26, 2006, 08:04:53 PM »

try syncing the carbs

Farre · « **Reply #8 on:** March 27, 2006, 02:50:36 AM »

i synced them in January. It's better but still way too lean. When i suddenly yank the throttle, the bike first lurches BACK, and then lurches forward!

gsxr400 racer · « **Reply #9 on:** March 27, 2006, 11:27:16 AM »

raise your needles up a skoosh.

Farre · « **Reply #10 on:** March 27, 2006, 12:01:28 PM »

Thanks! Will do!
Don't know when, maybe this weekend? The shit is i have to depend on somebody else as i don't have a car drivers license

Funny sidenote: the bike is working better now, i'm guessing because the temperature has raised quite a bit. It's indeed too lean