Oh ill get slated for this--- need help with bsa bantam

Due to an irresistable impulse buy i am the proud owner of a 1966 BSA d10 tidy enough but been off the road for the last 4 years .Now on getting it home i find it has no spark--ive fitted fresh battery --using my test light whilst checking the points i dicovered the whole bike is live engine/frame/petrol tank????--can anyone throw any light on the subject please(no pun intended probably going to regret choice of words there anyhooo all ideas welcome cheers Stu-

 

Hi Dingerbell You have on earth connection from battery to frame then, me thinks

 

Is it/should it be +ve earth? Some older bikes are.

That was the first thing that went through my mind when I read what the problem was ... although there's nowt up there to stop any stray thoughts doing significant damage!!

 

Apparently all Bamtams left the factory with 6v positive earthing but they can be changed to 12v negative.

This website might help.
http://roosterignitions.com/bantam.php

 

That would be "Bantams"!

 

If engine is live, what ever voltage or polarity is it has a earthing problem i would be looking for my voltmeter and heavy duty jump leads

 

ok thanks all ive had a better look tonight--checked for anything that could be earthing out taped a few dodgy wire ends -- no difference--points working ok powering on and off but still no spark?--strangely though the outside of the coil is live as is the rest of the bike but all the connectors are dead --Maybe should try another coil first ?

 

No do not change anything yet, tell me where you are earthing your test light ?

 

direct to battery negative terminal--

 

ok good with the test light probe start from negative post of battery follow wire from battery the thick one and probe the lead that connects to chassis of bike this is where it should connect to if bike is negative earth, let me know if it is negative earth ?

 

it appears to go from batt terminal to double brown wire one of which goes directly to what appears to be a resin filled regulator and the other dissapears into the harness towards the front of the bike--i cant see a negative earth to the chassis--oh and its had a 12 volt conversion--

 

oh and earth wire from battery has a fuse in it --

 

Has your test light got a filament bulb or led ? Have you got a testing voltmeter ?

First check this fuse with your test light to see if power is going through it,

This bike looks as if it is still positive earth, right lets put the earth of test probe on positive side and follow the thick cable to see where it connects to ? if it connects to frame or engine it is defo positive earth system bike.

 

Scuse my ignorance but if it's fused doesn't that mean it's the live wire not the earth?

 

Correct it looks like this is a positive earth bike just getting D 1962 to follow Positive wire to see if it is going to frame or engine of bike or has someone at some point put a fuse into this wire ???

 

Thank you all for your help --got the old girl running tonight --seems to have been a combination of crap points ropey ignition switch and bad earths (positive earths well spotted)--once again cheers

 

Well done my son happy days

 

thanks for taking the time out to help most appreciated Stu--

 

No problem if a positive outcome