3 replies to this topic

[mk1sdl]

Hi,

 

I am having problems setting up my carb properly.

 

As far as I can tell, there are three things that can be turned to adjust the settings..

 

• The mixture nut that sits underneath the carb below the jet
• A sprung screw at the front facing slightly downwards
• A sprung screw screw on the left (when facing the carb from the bonnet - no 1 cylinder to the right) which faces upwards

 

Even with the mixture nut wound all the way in, the engine revs still rise when lifting the piston carrying the needle

The engine revs won't drop below 1000 rpm even with the sprung screw at the front (fast idle??) wound all the way out

What does the other screw set? It appears to push up against the choke cam..

 

Are there default settings for each of these to use as a starter point for getting idle speed and mixture set up properly?

 

 

Many thanks!

 

 

[cal844]

You need to play about with the mixture, using the lifting pin might get it close (I have no experience using this method as I only use Hs4 carbs)

All I do is set the choke so the linkage is in the fully closed position. Set cable so the dash end is fully closed when the carb is fully closed but the cable is slightly loose.

There is a procedure to set the idle mixture and centre the jet in relation to the needle. (I THINK its level with the bridge of the carb then 2 full turns rich)

The small screw onto the choke cam is so the throttle is opened slightly with the choke on.

Hope this is some help... then again I may be totally wrong

Regards

Cal

Edited by cal844, 30 May 2020 - 08:10 PM.

[Homersimpson]

When lifting the carb piston you need to only lift it a small amount (I think its 1/32"), a lot of people push the plunger right in which doesn't give the right effect and leads to a false diagnosis.

[timmy850]

Is the timing set correctly at idle?

One screw is the idle speed, and the other one sets how much the throttle opens with the choke on

Is the jet raised back up and the choke loose?

What needle to you have fitted?