Greetings. I am new here and new to the world of BSA's.
I recently picked up a nice original 1967 Thunderbolt A65 for a good price. It sat a while with the previous owner who just bought it to restore it (I like it as is). So I've changed all the oils and cleaned out the gas tank. It fired right up, but did not want to idle so I pulled the AMALMonobloc carb off and dismantled it and cleaned it with Berrymans. I'm sorting a few more things out before I start it again.
The spark plugs in it now are NGK B8ES and they appear to be in good shape, but the manual says B7ES for single carb engines 1966 and onward so I went out and bought what the manual says. I'm told the top end was rebuilt and it does have electronic ignition on it.
Finally the questions---Should I switch to the proper B7ES or does it need the B8ES because of the electronic ignition?? Or does it even matter?? I just don't want to do any damage from too hot of a spark plug.
You are one luck man that is a nice BEEZA. OK you already did one of the best things for her and installed a modern ign. start out fat (IE) B8ES and work you're way to happyness. Remmember to jet for low end as well as mid. and high with the FEDS putting ethol and ketone in our petrol a little Marvel Mystery Oil added to every tank does wonders also. And remember it is better to have run fat and fowled plugs than run lean and burned hole in pistons or worse. Good Night and Good Luck Signed the GreenMonster
Good Night and Good Luck Signed GreenMonster
#26410 - 06/21/0711:56 amRe: NGK B7ES or B8ES - Does it matter? 67 Thunderbolt A65
EI instead of points shouldn't make any difference as far as plug choice is concerned.
With regard to plug selection, think a lot depends upon type of riding. If mostly around town and gentle touring I would think E7's are OK. Well at least I know several riders who haven't experienced any problem using them.
On the other hand if you are going to ride it hard, I would recommend the colder E8's to be on the safe side.
In order to negate the fouling potential of the colder plugs its a good idea to use the fine wire type (Gold palladuim, iridium platinum etc). Unfortunately I'm not up to speed at the moment as to whats available out there as fine wire plugs are concerned. Currently I'm using B8VS's (Gold Palladium) in my BSA R3 (different animal to the Thunderbolt I know)but they are no longer available as I understand it.
#26411 - 06/21/075:54 pmRe: NGK B7ES or B8ES - Does it matter? 67 Thunderbolt A65
Joined: Feb 2007 Posts: 2,200Semper Gumby
BritBike Forum member
NGK BR8EIX is the iridium version of a fine wire plug. Works fine, a bit sooty but the carbs may be running rich in the mid range. I don't know yet weither they are worth the extra cost. It's an on going project with the 1971 Thunderbolt. BTW I run stock points, NGK caps (5K ohm) and stock coils.
I'm about to do a 2000 mile service so it will be time to tweak the carberation again.
There is another thread that covers all the plugs from KLEG to Champion quite well on this (BSA) board.
Gaggle of BSAs a Honda an old BMW and a Montesa Parking lot Elf in training
#26412 - 06/21/076:15 pmRe: NGK B7ES or B8ES - Does it matter? 67 Thunderbolt A65
Thanks for the help and comments guys. I was pretty fortunate to find a survivor in good shape. Even my wife likes it.
I think I'll stick with the B8ES for now. Better safe than sorry I guess. I'll see how it does after a few rides and go from there. I fired it up today and it runs way better with the cleaned out carb.