M/C2 Sq4 SU jet adjusting tool

Post Reply
User avatar
Brian_Walker
Holder of a Nylon Anorak
Holder of a Nylon Anorak
Posts: 172
Joined: Mon Mar 19, 2018 9:40 am
Location: Sydney, Australia
Contact:

M/C2 Sq4 SU jet adjusting tool

Post by Brian_Walker »

A friend purchased a 1956 SQ4 some time ago and has been slowly fettering various things to produce a very fine machine that has no oil leaks (thanks to the pizza dish mod) and runs like a dream. Being a retired tool maker/fitter and with many years experience restoring vintage bikes he passed this tip across to me to post as he is not keen on social media and didn’t want to post it himself.
The tip relates to adjusting the jet position on a SU M/C 2, with this tool he made up you can adjust the jet position without removing split pins etc that you need to do with a standard spanner, you can even adjust while the engine is running. I haven’t seen this type of thing before but it may have been forgotten in the mists of time. He made his up from a old 5/8” or 16mm 12 point socket and a cheap a shock adjusting tool.
The socket is cut down to remove the bit for the square drive so only the 12 point part of the socket remains. This is then welded (silver soldered) to the shock adjusting tool and finally the socket is cut down the middle to leave the two half socket bits concentric to each other.
Photo below shows the 1) finished tool 2) tool going around the linkage 3) adjusting the jet up or down to centre it properly so it doesn’t bind. Procedure outlined in the manual is followed verbatim and would probably be needed if cork gaskets were replaced or carby dissembled. His bike ran well before but after tweeking acceleration is smooth as, Thanks Greg for passing this on!
fig1.jpg
fig2.jpg
fig3.jpg
1951-52 VCH under restoration
MGriffin
Holder of a Nylon Anorak
Holder of a Nylon Anorak
Posts: 233
Joined: Sun Oct 06, 2019 1:04 pm
Contact:

Re: M/C2 Sq4 SU jet adjusting tool

Post by MGriffin »

or…..you could just buy a Jet adjusting spanner?
Attachments
E8F51AE3-C04B-4DA9-9DB3-DD425AB0CBF5.jpeg
Regards
Michael.

28 Model A
28 Model C
48 Red Hunter
User avatar
Brian_Walker
Holder of a Nylon Anorak
Holder of a Nylon Anorak
Posts: 172
Joined: Mon Mar 19, 2018 9:40 am
Location: Sydney, Australia
Contact:

Re: M/C2 Sq4 SU jet adjusting tool

Post by Brian_Walker »

It doesn't look deep enough to use without removing split pins and disconnecting linkage.
1951-52 VCH under restoration
Post Reply

Who is online

Users browsing this forum: No registered users and 3 guests