Just done an overall on the carbs (the missus still ain't talking to me :x  did it on the kitchen table, spilt petrol all over it, now it's got a couple of nice stains on it). Any way i'm a little confused. my manual says turn out the mixture screw 1.1/4 turns (it's a 1991 bike) but when i dissassembled the carbs they were set at 2 turns?? and i've read on this site about turning it 3 or 3.1/2 turns. What does this screw actually do and what is the best setting??  its fitted with standard 40 pilots & 120 mains.
Also, is balancing carbs really necessary as i dont want to fork out precious cash on something i'm only going to use once in a blue moon.

Beats me. I would guess that balancing the carbs would be important.

I don't really have an answer to this question. I just wanted to get to 400 posts this evening and felt bad that nobody had answered this question in nearly 7 years.

You can make your own sync tool for a few bucks:

http://www.google.com/search?sourceid=chrome&ie=UTF-8&q=build+carb+sync+tool

The mix screw adjusts the amount of air allowed to draw fuel through the low speed circuit.

When you turn it in, you occlude a passageway that lets air through, so less air gets through and less fuel gets drawn with the air.

When you turn it out, you open up the passageway and more fuel comes through with the air.

In other words, turning it out enrichens the mixture, turning it in leans the mixture.

From the factory, it's set around 2 turns out.  What manual do you have, btw?

Buy a Carbtune pro. It's cheaper than having your shop balance your carbs and you can sell the tool after using it to make it even cheaper.

You can do a pretty good job syncing the carbs by eye.  Or you can create your own carb sync tool for about ~$12 using colored water and aquarium accessories.  Here's mine:

I guess stoo felt ignored and left.  He hasn't been seen since August of 2003.

- Porkchop

Quote from: XealotX on May 09, 2010, 08:25:09 PM
I don't really have an answer to this question. I just wanted to get to 400 posts this evening and felt bad that nobody had answered this question in nearly 7 years.

Quote from: XealotX on May 09, 2010, 08:25:09 PM
Beats me. I would guess that balancing the carbs would be important.

I don't really have an answer to this question. I just wanted to get to 400 posts this evening and felt bad that nobody had answered this question in nearly 7 years.

Also having done/tried a carb synch this weekend I disagree. It's a pain in the rump on an 04, and I probably did more to mess up the carbs in the process than I did to correct anything...

Quote from: 007brendan on May 09, 2010, 11:10:17 PM
You can do a pretty good job syncing the carbs by eye.  Or you can create your own carb sync tool for about ~$12 using colored water and aquarium accessories.  Here's mine:

or use gas instead of water so if it gets sucked into the engine it just burns

oh, and the mixture screw lets more or less gas into the mixture. theres a port that the gas takes that goes past the inside tip of the mixture screw on the inside of the carb, screwing the screw out makes the path bigger, thus allowing more gas to flow and enriching your mixture and visa versa

Quote from: gregvhen on May 10, 2010, 08:43:37 PM
or use gas instead of water so if it gets sucked into the engine it just burns

Great idea!

Synchronizing the vacuum between the carbs ensures that one cylinder will not be working harder than the other one, which would lead to premature wear, inconsistant carburetion, hesitant acceleration, overheating, decrease in power...