SV poor running question

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bevanclark
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SV poor running question

Postby bevanclark » Mon Jul 02, 2018 12:21 am

Hi folks,
Trying to assist a bloke on another forum:
1932 BSA 500 sv, only starts and runs reasonably on full retard. Says it runs in 1st & 2nd, then dies if he changes up. He reckons it goes ok up and down hill.
Incorrect timing is the obvious cause, but he says it is correct.
Any other possible causes fit these symptoms ?
Cheers,
Bevan

nevhunter
Holder of a Golden Anorak
Holder of a Golden Anorak
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Re: SV poor running question

Postby nevhunter » Mon Jul 02, 2018 1:41 am

When in doubt start with the magneto. Perhaps the timing between the points and the magnet is wrong due to mixing parts sometime in the past or the "weak" key is damaged on the taper of the points assembly where it fits onto the end of the armature. IF this is wrong you lose all spark at some place in the advance retard movement. Check also the High tension slip ring isn't worn hollow where the spark occurs or brush sticking and the spark is generally adequate. You should get about 1/4 inch spark onto the plug when the motor is at a fast idle . Don't use an "R" plug or resistor "suppressor" leads. Check point gap. It may also be geared too tall. and see if lowering the airslide helps at higher throttle opening when it dies. Nev

bevanclark
Posts: 24
Joined: Fri Jun 08, 2018 3:58 am
Contact:

Re: SV poor running question

Postby bevanclark » Mon Jul 02, 2018 7:02 am

Thanks Nev,
Will pass it on.
Cheers,
Bevan


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