Card Adjustment Screws

[Whiskey69]

Hi Guys, just when I thought the BSA Starfire is the best bike ever made…….
I had her starting well (if the clutch doesn’t slip), good idle, going pretty well, looking good, life was good, but……
First noticed the idle was fluctuating, then just really high, like 30mph in third with no throttle! Try stopping, holding the brake and clutch and turning the ignition key off without letting the engine bounce off the rev limiter (is there one?)
Quick inspection, it seems the vibrations are winding the adjustment screws in, both of them, so winding the idle screw out kills the engine, arrrrrrrrh, any way got home, stopped twice in 12miles for adjustments.
Ordered and fitted new o-rings as that is all that keeps the screws in place, but just 500 miles before I had replaced these?
Do you guys use anything else to keep these screws secure?
Cheers
Whiskey69

[tdc]

When you say' the adjustment screws' do you mean the throttle stop screw and the pilot adjustment screw ? assuming that you have an Amal carb.

[DAVE BRADY]

Hi,

The new 'O' rings should make a big difference.  If they go in easy then they are too thin so try a slightly thicker one.  It may be a squeeze to get them in but they will hold the screws in place.

Dave.

[A10 JWO]

Hitchcock M/C's are brilliant for Amal Parts and they know what they are talking about. Normally overnight post.

[chaz]

http://amalcarb.co.uk/carbspec/carburettor/spares/id/4878/
does not show o rings. but the part description does say with oring. it is possible the threads in the body could be worn, the other thing is the pointed ends can get worn.
once set and happy , there are a couple of options, a non setting thread locker, medium strength or another fix is a wax seal,

[BEESY]

Mine has o rings. Got new ones in a re furb kit from Amal.

[Whiskey69]

Hi Guys
Latest, i had fitted new o-rings when i purchased a carb rebuild kit a while ago, and new idle and mixture screws.
Had a good look at them measured them up, I think the o-ring size should be BS006, so tried these, I bit more resistance but not secure enough in my opinion, so tried the next size BS007, the only way to get these into the carb was to give the screw holes a very light lead in, by hand with a drill
That’s better, they won’t move now, unless you try
Went for a run, back to perfect normal, good idle and starting
Thanks for your help, I hope this helps others
Whiskey

[courtney]

That's good to know and thanks for the update. It's helpful looking through old topics to find a solution has been found.

[Mike40M]

On the NOC forum, the same problem was discussed a few months ago. So it happens to Nortons too. On quick fix while waiting for new O-rings was:
" in the meantime some dabs of rubber solution applied to bridge the ends of the screws to the carb body have proved effective."