Weber DCOE Idle adjustment help please

[simon metcalfe]

I am trying to set up the idle speed on my crossflow. The warm engine idles at about 1100 rpm - however, whilst the idle adjustment screws on the rear carb impair or improve the performance in the usual way those on the front carb seem to make no difference to the set up at all - even if screwed down to seat completely so I can't set the idle speed up correctly across both carbs. I've unscrewed the screws and cleaned - all seems ok there and have also removed and checked the idle jets themselves - again all ok. The throttle cable, linkage etc is also all ok. Any thoughts or suggestions much appreciated.

[John Alston]

Make sure both carbs are drawing in the same amount of air by balancing with the throttle stops. If you have not got a suitable gauge, a reasonable job can be achieved by using a length of tubing held to the ear and into each choke in turn and adjusting the stop screws to get an even hiss. Once this is achieved, fine tune the idle with the air control screws.

[Birkin S3 ZA.]

 

Have you balanced the carbs properly?

 

Start with balancing the carbs followed by setting the idle mixture and the idle speed.

 

Idle speed and idle mixture might have to be done several times to get it right.

 

If all the jets and passages are clean it should be straight forward,

if you still struggle look for blocked jets, or air leaks, even ignition problems.

 

Chris.

[Eugene]

whilst the idle adjustment screws on the rear carb impair or improve the performance in the usual way those on the front carb

Those do not sound like the idle adjustment screws... they sound like the idle mixture screws.

 

The idle is adjusted by the throttle stop screw.

 

But, you do need to get the balance correct, and possible air bleed too.

 

It is actually very simple - see: http://www.carburetion.com/Weber/adjust.htm

[simon metcalfe]

Many thanks all for this advice - I had overlooked the fact that I need to balance them first - then adjust the idle mixtures. Will try again....Thanks again, Simon

[Gordon C]

If you fancy treating yourself to a to a nice balance tool have a look at the Synchrometer. Very easy to use and works a treat on carbs as well as throttle bodies

[simon metcalfe]

Balancing first made all the difference - now running perfectly. Many thanks for the Syncrometer link Woosh - I am already convinced I need one of those

 

Thanks again to all for your help, Simon.

[Neil66]

Synchrometer.. pah...!

 

In my day we did it with a length of syphon hose - one end down the barrel and the other in yer ear 😬

[CaterBram]

But a synchro meter will still work in the middle of a noisy paddock where you would not here the sutulties of the hose

 

Edited by - CaterBram on 30 Apr 2013 20:49:03

[simon metcalfe]

...have to say, I used the length of tubing today and it worked very well - will be interesting to compare my settings achieved with the tube with the Syncrometer measurements.