1971 A65T Thunderbolt - The other 650!

[Semper Gumby]

Hi Guys and Gals,  

I bought a 1971 BSA A65T Thunderbolt with matching numbers yesterday.  It wasn't running properly.  After adding one automotive plug wire, it is singing an amazing song.  One of the baffles is missing and its a bit loud.

My question: The shifter lever spring is fine but the tranny hangs between 3rd and 2nd when down shifting.  I have a hole 'nother tranny so I have some parts to work with.  My question is which ones?

BTW - It's black but originally green and white.  I have the original tank and side covers still painted green and white.  My understanding is that the frame was dove grey but the only place that appears is under the black paint on the shocks.  Everything works but the turnsignals.

Thanks,

[Justin B.]

Sounds like an interesting project.  Any pics?

[Semper Gumby]

Greetings from Sunny Cold Wichita.

Pics on Tuesday night.  I'm on the road.   :-/

[nhmaf]

This sounds like a fun project - a number of years ago, I was looking for a 'project' bike, and
almost bought a somewhat running BSA Lightning for the project.   I then was distracted by
Nortons (and like many men, I still am, even without the Norton Girl adverts), before I finally
decided, that if I worked on a bike, I'd want to be able to ride it on trips over at least several
hundred miles, and went back to the Marque which I knew best, and which wouldn't let me
down (at least as frequently) and finally bought my R65LS (Rosie).

Pictures when you can post them, please !!

[Ed Miller]

Cool!  Is that a single carb model?  I'm not very familiar with BSAs, tho a nearby friend of mine has a '70 Lightening, dual carb.  I want to race him on my '70 Bonneville some time.  It helps my confidence that he weighs at least 40 pounds more than me....

If the wire you used was resistor wire you may want to make a new pair of plug wires when you get a chance.

Good luck with it and I too am looking foreward to pictures.

[NC Steve]

Yeah, Ed, The Thunderbolt was BSA's single-carb 650 twin, about like Triumph's TR6. Both were actually a bit more rideable in about 90% of situations than the "hotter" twin-carbers, and much easier to keep in tune, but neither had the hotrod "wow factor" and didn't sell as well.

But a race between your '70 Bonneville and your buddy's '70 Lightning? Now THAT I would love to see; hell, y'all could sell tickets!! Stats-wise, the BSA's supposedly ran just a leetle quicker than the Triumphs, although most of that was probably the rider and most likely would still be the case if the bikes were in similar condition. Unless your friend's a much better jockey, I'd say the 40 lbs. would tip it to you! [smiley=thumbsup.gif]
Good luck, and keep us posted about the race! 8-)

[Ed Miller]

Yeah, Ed, The Thunderbolt was BSA's single-carb 650 twin, about like Triumph's TR6. Both were actually a bit more rideable in about 90% of situations than the "hotter" twin-carbers, and much easier to keep in tune, but neither had the hotrod "wow factor" and didn't sell as well.

I don't know, I too read about the rideability factor on several Britbike forums, but how many BMW twins came with single carbs?  Any R65 owner knows how to syncronize his carbs, and both Bings and Amals basically used O-rings to keep the mixture screws from moving.

As for the race, my buddy always seems to have problems with his Lightening that he's scared to tackle.  Something about shimming the crank end play; my Bonnie is set up differently so I don't know what he's up to.  I suspect you will learn, however....  

Good luck, fun stuff!

[Rob Valdez 79 R65]

but how many BMW twins came with single carbs?  

Um, How about the R16?

From the very cool website, http://home.planet.nl/~motors-20th-century/motors.html (thank you, airhead!)

[SCJJR65]

Yeah, I'm looking forward to seeing some photos of your latest "toy"!  

[Ed Miller]

Um, How about the R16?

Dang Rob, that thing's prettier than my R65!  Is that some sort of sprung rear hub or just a hard tail?  Why are so many bikes (and cars and trucks!) from the 30s so good looking?  I love that decade in motor vehicles.

Thanks for the picture.

Here's one from the other end of the decade:

[Rob Valdez 79 R65]

No Ed, back in those days, the only springs were the ones under the saddle!

[Semper Gumby]

Gack.  The adventure continues!

I'm on the road again.  It's a single carb bike. (By definition all BSA Thunderbolts are single carb.)  And it runs (most of the time.)  

I blew a main fuse when a wire came off the running light in the speedo.  Couple of nice GA rednecks (quite drunk) pulled up and then volinteered to get me another.  Came back ten minutes later with a whole box of various fuses and got me going again with one spare in the pocket.  

The one design feature of the single carb T-bolt is that when it runs out of gas...it runs out NOW (like when you take off with the petcock closed!)

Yep the spark plug wires were carbon resistor types (woven carbon fabric - I never knew such existed!) so new solid core ones on order.

Tranny update:  It shifts OK but when down shifting I have to let the lever snap back to center in order to get it where I can select the next gear down.  Any ideas on this would be greatly appreciated.

Sorry I don't have pictures yet.  I promise next week!  

Bike has a great sound when running handles well.  Drum brakes and right foot shift take some getting use to.  Hey I don't have to balance the carb.  At the moment there is a K&N filter on it.  I have the original side covers and filter set up which I am planning to put back on.  When I put the colortune plug in to set the mixture I noticed after setting the idle mixture that the needle/main jet mixture was running rich.  I think there is not enough air coming from the K&N pod filter.  That is unless the needle main jet have not been changed!

Bill

Greetings from cold and dark Detroit.

[Semper Gumby]

Here is a picture of a restored 1971 A65T Thunderbolt.  Mine has all the parts but a black frame.

http://www.geocities.com/MotorCity/Downs/5106/rafflebike2005.html

[NC Steve]

Too cool, brings back lots of memories (and not all good)!

Hey, once you get this bad boy rolling again, maybe we can settle the single vs. dual carb arguments, and you and Ed can race! His buddy with the Lightning keeps finding excuses to wuss out against his Bonneville, and curious minds need to know!

Put me down for a coupla tickets to the show, for sure!!

[Semper Gumby]

Lightning Vs. T-bolt - I'm told that a T-bolt is quicker off the line.  But the Two carbs bikes have a stronger top end.  I think its a bunch of hooee.  The two carb bikes, when properly tuned will beat my T-bolt every time.  My buddy's 1969 Firebird Scrambler goes like stink and really comes on the cam above 4000 RPM.  Then I start thinking about drum brakes and Dunlop K70 tires and all my speed desires disappear in the dust.

I will probably put a larger than stock counter shaft sprocket on this bike so it will turn over at a lower RPM at cruise.  Less buzzy and more pleasent to drive.  This will of course be at the expense of speed off the line!

Greetings from Cold New York's LaGuardia Airport.

Home tomorrow thank goodness.  My R65 waits patiently in the company parking lot.  I can hear it calling in the distance...