Motorcycles - Ernie Dube
Tech Tip:
Carburetor Synchronizing, Cleaning & Tune Up

For general non-specific make questions

Bad Carbs?

Ernie Has done it again !

by Roger Chartier... and I'll ask Ernie to put in his 2 cents on the subject.

So for my part in this article I want to say my 1980 Suzuki GS750 was running like crapola. I took off the carbs because they were leaking gas from the fuel T. and must have needed cleaning. When I got to a problem loosening screws, rather than strip the screw heads and wreck the whole thing, I'd better ask Ernie to do it.

I gave him the carbs and he got them cleaned up and tightened the thing up replacing O rings etc. I put them back on the bike...sorta.

The airbox rubber boots didn't all fit onto the carbs and I realized that the guy who sold me the bike knew that all along.. Well after busting my butt trying to get in all on correctly I took the whole she bang to Ernie Dube.

He gave me a ration... "Don't you read my articles?" I said of course I had read them...but.

He reminded me about the dish soap method of lubricating stuff to get it on. After he got the airbox tightened onto the carbs he did some magic tricks with hoses and fluids and an intravenous drip to the gas inlet on the carbs and tuned the carburetors for me.

I tried to see what he was doing but like a good magician you never get to see all the tricks...As I rode home I felt the joy of what a bike should ride like. Vroom, Vroom YES!

I wanted to sell it but now???  I like the new feeling of Vroom, Vroom... spunky bike.

Now, as soon as Ernie gets a chance (I hope)

   I'll ask him to fill in the facts as they actually were with some helpful info. He is a very busy guy, so wait until he fills in the rest of the story...

So, Ernie Dube,...what do you have to say? We're waiting...

Ernie's reply:

By Ernie Dube:

Tech Tip: Carburetor Synchronizing

  If you own a bike that has multiple carburetors, they should be synchronized. This means that all the carbs should get the same amount of air in each intake manifold. This is achieved by installing adapters into each intake manifold so vacuum lines can be attached. At the other end of the vacuum lines is some sort of device that can measure the amount of air each carb is allowing to pass. I use a manometer.

   The carbs are adjusted individually according to the manufacturer specs. using special equipment and patience.
By adjusting them, you are in a sense creating one large carb. If you have one carb out of adjustment you can loose as much as 25% of power to the motor. For example: if you have a 2 carb motor, if one carb is out of adjustment, that cylinder is not getting as much air as the other one, which in turn forces the other cylinder to carry the load. (The air is very important in the operation of the carburetor. Air is what caries the fuel into the cylinder to burn. The vacuum caused by the air movement, makes the carb work by moving fuel through a series of orifices). This can eventually cause uneven wear of the valves, bearings, vibrations, loss of power on acceleration and most importantly poor fuel mileage!

   Carburetor synchronization should be checked every couple of years for maximum motor performance. All the tune-ups one could possibly do, could not compare to a good synchronization.


The Author - Roger Chartier