Jet assembly & carb adjustment

[annsteel]

Hello, I need to replace the jet assembly as it is leaking and adjust my su carb.
Can you assist please?

[philthehill]

All the information you require is contained in the link below and the sub links contained within it.
https://sucarb.co.uk/technical/category ... rburetters

[annsteel]

Thank you Phil. As a basic mechanic only can you give me more info please. From your experience or others. Thanks Ann

[philthehill]

Replacing the jet assy is relatively easy and if you follow the instructions in the wksp man there should be no problems.
Make sure that the jet/seals are ethanol compatible.
If you are doing a straight jet replacement you may find that there will be no requirement to centralise the jet. If the damper pistons falls with a clunk all is ok.
Make sure that the union seal on the flex pipe into the bottom of the float chamber from the jet is in place when you screw the union into the bottom of the float chamber otherwise it will leak.
Please feel free to come back on here if you want further advise.

[svenedin]

As Phil says, it is quite straightforward to replace the jet assembly but it is quite easy to mess up fitting the jet fuel pipe to the float bowl especially if you are doing this with the carburettor in-situ rather than on the bench. If doing this with the carb fitted to the engine, at the very least, remove the air filter and housing and also the plate that the air filter baseplate sits on (you will need a new gasket). This is so you can see what you are doing properly. The new jet assemblies have a Viton O-ring for sealing with the float bowl. This is ethanol resistant. It is essential to ensure that all of the old O-ring has been removed if it either sticks and does not come out with the jet pipe or disintegrates (and it is next to impossible to see with the carb installed). It is better to do a jet assembly replacement on the bench if you have never done this before. Remember you will need a number of new gaskets if removing and re-installing the carb.

Have a look at this video which explains it very well.

https://www.youtube.com/watch?v=ZPzu2zzyGCQ

Stephen

[annsteel]

Hello Stehen,
Thank you. I have studied the video. I can see the brass nut goes into the dash pot but the black plastic piece on the other end? How does that fit? There does not appear to be a fitting? Thanks....

[philthehill]

The black plastic of the jet is secured by a screw to the choke linkage.
The flexible hose of the jet just screws into the bottom of the float chamber.

[Davemate]

Have a look on here
It’s a idiots guide (no offence meant)

https://www.mgexp.com/phile/1/283532/SU_idiot_guide.PDF