Tuning 850 carb

Liebherr1750

New member
Joined
May 21, 2018
Messages
12
Hello guys , I have a 1974 seat 850 with Weber carb I’m having trouble getting it to idle no matter what I do it keeps hunting and don’t react to the air screw should there be a rubber o ring on the air screw ? Can anyone help maybe had same problems
 

timmycm850

Active member
Joined
Feb 28, 2016
Messages
517
Hi Liebherr.

locate the idle jet/s on your carb and take it/them out separate the two halves and blow them through with air and then refit.

look through your workshop manual to ensure you are cleaning out the idle jet.

next put some fresh petrol in the car as modern petrol degrades like its going out of fashion( oh petrol actually is! ).

Tim
 

Crawling Finn

New member
Joined
May 1, 2021
Messages
1
Hi Liebherr,

Small air leak could cause symptoms like that, and there is a very simple method you can use to check if that's the case: Start the engine and whilst it is running, spray small amount of some flammable liquid around the carb flange and other areas where the leak could be. For example carb cleaner or brake cleaner works well. If the revs rise you know that you have a leak.

Small leak wouldn't affect running on higher rpm when air flow is greater, but on idle the mixture will lean too much for engine to run correctly.

Cheerio,
Crawling Finn
 
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Liebherr1750

New member
Joined
May 21, 2018
Messages
12
Cheers guys for info, I found the source of the problem I was missing an o ring from the idle jet ,
 
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