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1971 BSA Thunderbolt Project

Discussion in 'BSA' started by FreeRadical, Apr 16, 2019.

  1. FreeRadical

    FreeRadical

    Joined:
    Dec 5, 2014
    Good afternoon! I recently acquired a mostly-all-there Thunderbolt and just went through all of the maintenance procedures I know to be of most importance before trying to start her up. All the fluids have been changed, rockers and cylinders lubed up, new plugs and the carburetors have been thoroughly cleaned and rebuilt. It has a new AGM battery as well.

    Everything seems to be in order....BUT...I cannot get the engine to fire up. I have a decent spark on both plugs. Just one small "pop" of the engine is all I've been able to achieve so far. Hopefully, someone can give me some suggestions on how to get this old gal running. I'm stumped...

    Thanks!
     
  2. Bob Z.

    Bob Z.

    Joined:
    Mar 30, 2012

    Do the spark plugs have fuel on them after kicking over several times?
    If not, perhaps the pilot jet and passage is not getting fuel past the carbs.
    On a 1971 the pilot jets should be located behind the air adjuster screws.
    But maybe they have the early style pilot jets screwed into the bottom of the carb body.

    One other guess, try and change over the left and right ignition coil wires.
    Good luck with it.
     
  3. alan hodge

    alan hodge VIP MEMBER

    Joined:
    Oct 10, 2017
    clean pilot jet with #78 drill bit or geetar string....and lots of carb cleaner from spray can....there's a 72 and a 68 A65 in my garage run non ethanol fuel if you can get it if not keep startron or stabil marine grade juice in gas...…...pilot jet is behind air screw
     
  4. FreeRadical

    FreeRadical

    Joined:
    Dec 5, 2014
    Thanks, Alan. Yeah, I'm aware of that tiny hole and I believe it's clean. I ran it through my ultrasonic a few times and ran a tiny wire through it. I started with 1-1/2 turns out on the pilot jet screw (???). The choke lever is missing from the bike, but I'm not sure how much those are really needed. My last bike didn't have one either.

    I did get it to start yesterday for a brief moment. It won't stay running and I get quite a bit of banging and popping when trying to start it. I was crossing my fingers that the bike was timed correctly, but based on the PO's handiwork on the breaker plate screws, I have to assume the guy was no mechanic. So, I guess I'll be looking into that today.
     
  5. alan hodge

    alan hodge VIP MEMBER

    Joined:
    Oct 10, 2017
    get a pazon and podtronics while you are at it
     
  6. FreeRadical

    FreeRadical

    Joined:
    Dec 5, 2014
    Thanks! It seems like I had some luck yesterday getting it started and idling pretty well. Before I sink too much into it, I need to put the tank on it now and ride it down the road. At this point, I'm not sure this is a keeper for me. But I agree that anything to make it run more reliably would probably be a good investment for someone.

    Does anyone prefer one electronic ignition over another? Boyer seems to be the go-to, but are there other manufacturers out there for less that work just as well?
     
  7. alan hodge

    alan hodge VIP MEMBER

    Joined:
    Oct 10, 2017
    I prefer pazon due t oits ability tokeep going even if battery voltage drops below 12....I have had both boyer andpazon..pitch in $50 more and get tympanium or pod tronics
    PS you will need 2 6v coils for electronic ignition
     
    Last edited: Apr 18, 2019 at 1:39 PM

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