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MG TD TF 1500 - My SU Carbs

I was going to send my carbs out to be rebuilt, but after thinking about it, they work perfectly, engine idles like a dream and when giving the throttle a little push, the engine snaps to life instantaneously with no hesitation! My question is, the primer jet on the bottom,(illustration), is stiff and has to be forced slightly to return it to the rest position. How can I correct this so they work freely? PJ



Paul S Jennings

Paul, obvious thing you probably already verified, but is your return spring correct, part 21. Regards, Tom
tm peterson

Check Toms' suggestion first then try replacing the washers and cork seals.When these start to degrade they can make it harder to turn, esp the big cork seal at the top. Lastly make sure the jet is properly centered.
Geoffrey M Baker

Tom, the return spring seems to be ok, I believe the seal might be too tight on the jet. I'm going to take Geoffreys suggestion and order new washers and seals. Question, can I replace these without pulling the carbs? The side panels will be off again after I get done fitting everything up on the sheet metal, so the carbs will be accessible again. PJ
Paul S Jennings

Gents,
Also, pull part 20 (Moss Illustration) and polish with 2000 grit wet paper or a quality metal polish. Be certain the through hole has no burrs. Submerge the cork seals in light oil for at least 24 hours. Reassemble and it should return smoothly if the springs are good. If you use too long a cotter pin at the bottom of the jet connection 9part 20 again) it can contact the bottom of the jet nut and prevent jet from returning to choke off position.

Jim Haskins 1953 TD
J. M. Haskins

Paul S. You can pull the parts in your red marking out together by disconnecting nut
# 20. All parts will come out down.
Thoralf. Norway TD 4490
Thoralf Sorensen (TD4490)

Paul, you can pull the entire jet assembly out as a single piece. Jim is correct, soak the seals for 24 hours in oil. Make sure the brass concave washers face in the proper direction when reassembling, and ditto to Jim's suggestion about polishing the jet tube (20). Once reassembling, the big cork seal at the top should pretty much disappear into the metal washer (#25?) and you can reassemble it all as a single unit and return to carb.
It should all fit smoothly and turn easily if not, check the centering on the jet and try alternately easing the cover off and on and centering the jet until the piston drops smoothly, then tighten all down.
Then put return springs back! I left out the last step and wondered why everything was suddenly running rich again:)
Hopefully all will be well...
Geoffrey M Baker

This thread was discussed between 04/06/2014 and 05/06/2014

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