I have found out why the Sprint transplant won't fire, I rebuilt the carbs and freed everything up; except the idle screw. They are both seized in the fully closed position. They also look to have the structure strength of twiglets, so I am very worried about shearing them.
The carbs are of course full of petrol, so heat is out of the question. It looks like I will have to take them off if freeing fluid doesn't do the trick and when does any freeing fluid ever work?
Oh well at least I got the downpipe on, with the world's most inaccessible bolt locations.
arggh idle screw seized
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cleverusername
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yorkshire_spam
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Re: arggh idle screw seized
Plus Gas or a mixture of acetone and ATF.
A good soaking.
Then gently tighten and then loosen.... but be prepared for the possibility of it shearing!
A good soaking.
Then gently tighten and then loosen.... but be prepared for the possibility of it shearing!
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MIG Wielder
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Re: arggh idle screw seized
Over the years S.U. carbs; had different solutions to stopping the idle screws vibrating loose. Some have springs ... and some have small locknuts at the base of the screw. If you have an early 1850 parts book have a look on page 19-25. The adjusters are 511726 and the small locknuts are 108350. From memory the lock nuts are an odd size. 4BA comes to mind.
Tony.
Tony.
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dollyman
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Re: arggh idle screw seized
Also try tapping them gently with a small hammer, that sometimes works, well as tightening before undoing as said.
Cheers, Tony.
Cheers, Tony.
NOW A CLUB MEMBER 2017057 
Re: arggh idle screw seized
The idle screws wont stop it firing. Choke out will be off the idle screws on fast idle anyway. Unless I missed something?
Tony
Tony
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xvivalve
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Re: arggh idle screw seized
I'm not sure if there are any idle screws in there as it has been raided several times at shows, but I have a box of dismantled carb components I can have a look through for you if the do shear (and you can successfully extract the bost bit)
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cleverusername
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Re: arggh idle screw seized
The fast idle screw isn't touching the cam, so something is off.
I have taken it apart to check top dead centre. Took the plugs out and physically checked the piston. Can't check compression as the compression gauge we have doesn't work with recessed plugs. However it does have new rings, so in theory that should be ok.
I have a spark, it is roughly timed right, so it must be a fuelling issue.
