jscobey

What are some signs that your carbs need to be balanced? How often does it need to be done? Anyone come up with a simple DIY gauge to balance them? I've seen the tubes filled with liquid but is that the easiest thing to make?

Carbs still seem to be a bit taboo to me but I wanna make sure I'm keeping them in good shape.

NZSpokes

Ive tried the make my own version and it kinda worked. Then I bought a Carbtune from the UK. Brilliant thing. Balance if you have worked on the carbs or done a valve adjustment. Ive set mine up so its a 5min job with hoses tucked behind the frame rails.

kenmoore

Carb tune from the U.K for me as well.

As we say in Oz , piece of **** and so simple.

Tucked my takeoff hoses behind the frame rails as well.

This is a great mod that makes syncing a breaze.

Can post pics jscobey if you like.

E.Marquez

Any time they have been off or adjusted
Any time the motor is doing most anything it's not supposed to,..carb fart,,, random idle, ect.. take a few moments to sync the carbs.

Many have good results from a DIY gauge, I still like and use my Motion Pro carb sticks.

sailorjerry

This is the one I made.


http://m.instructables.com/id/DIY-Du...tor-Sync-Tool/


It works well just make sure when you make your adjustments that you give the liquid time to level off. It's really easy to go to far on your adjustment with this set up, so make a minor adjustment and let it sit for a minute and recheck.

superman22x

What you are making is a manometer. Very simple, and the DIY is 100% as accurate as the expensive ones. Especially with a 2 cylinder. A simple U-tube manometer is all you need. I have mine set up for 3 cylinders, and a valve on the bottom with a line that can pull in transmission fluid from a bottle. But I'll snap a picture and try and remember to post it. Cost me next to nothing to build. Transmission fluid actually would allow for more accuracy than the mercury ones.

EDIT:

Ok, this thread inspired me to finally sync my carbs. Hopefully that fixes my idle issue (bike sometimes dies out, other times idles at 1800+).
I took a picture of my manometer. But first, I'm going to get into the science. I'm a Mech engineer, so this is my thing, haha. Manometers work on Bernoulli's principle. Pressure (vacuum of the intake) is equivalent to potential energy (height of a column of liquid). Rho*gravity*height = pressure. Therefore, the difference between two columns of liquid is equivalent to the difference in pressure. We don't care what the actual pressure is, as long as it's the same in both cylinders. So that's why the actual height doesn't matter.
Manometers can be built two different ways. As a U-tube manometer to measure a pressure difference. Or a reservoir manometer, that just draws a column of liquid. Mine is basically both.

Notice the center line is not connected. A third or fourth line can be added easily to sync more cylinders. I found the VTR really easy to sync compared to the three and four cylinders I have done in the past.



So in the picture here, I attach the two lines to the two cylinders (you will need vacuum hose off the cylinders to attach to this clear tubing, the clear tubing will melt on the cylinder otherwise), with the valve open. On the otherside of the valve, the line dips into a bottle of trans fluid. Initially, I use this to draw fluid into the manometer. I also use this to get the carbs within reasonable sync if they were really bad. Then I close the valve with a few inches of fluid in each tube, and adjust the screw with the bike running until both columns are the same height. Sync at a speed a little above idle.

When building the manometer, I used fittings from Menards and line from Menards, along with a few vacuum fittings. It helps if you add in restricters also. I recommend 1/4" or bigger line for the bottom portion, otherwise your fluid columns will dance around too much and take a long time to return to static.