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New owner of 71 Thunderbolt with question #711106
10/10/17 3:50 pm
10/10/17 3:50 pm
Joined: Sep 2017
Posts: 65
Windsor, Virginia, USA
V
VANDOLSON Offline OP
BritBike Forum member
VANDOLSON  Offline OP
BritBike Forum member
V
Joined: Sep 2017
Posts: 65
Windsor, Virginia, USA
Hi!
Been riding since 1970. Owned to Triumphs back in the 70's. A 1965 TR6 and a 1959 T120. After that rode Harleys until
a year ago (arthritis, back surgery, etc) when I had to give up riding long distances. Wanted a British project bike to
restore. Found a 1971 Thunderbolt locally. Bike was running and I rode it. Engine really strong and shifted well. So
paid $3000 for it. I knew it had a lot of work to restore, but...the guy was restoring a 1968 BSA basket case and needed
$3000, so...I understand that...bike really worth $2500 max....but...I have restored bikes in the past so...gave him what
he wanted.

The bike: Tank was original but repainted Sterling Moss (green) and white. Very nice tank. Forks were in good shape
except the upper yoke was destroyed by someone trying to remove the fork lock. Engine is fine. Frame is okay (rusted
a lot). Everything else has to be replaced or re-furbished. If it was painted, it was rusted and chipped. If it was chrome
it was rusted and pitted (wheels and fenders). If it had a bolt, it was rusted and most were seized. So far have spent
around $5000 on parts (fenders, new repop seat, entire wheels and tires, speedo replaced with a refurbished Smiths,
headlight shell, warning lights, cloth harness, every nut and bolt and screw, top yoke, new fork lock, new ignition
switch (correct NOS with internal lock with keys), and so on and so on).

I know the bike will not be worth what I am putting into it, but...it is a hobby and keeps me in the motorcycle world
that I have been in since I was 15 when I got my motorcycle permit. Can't live without a motorcycle! Has been my
life.

Anyway....to my question:

1. As I said, all the bolts on the bike were rusted and most seized. Took me over 2 hours to get the swing arm bolt
out!! Had grease the bearings, then spray it with a penetrating spray and wait (multiple times). Finally got it
pounded out....now my problem...the "Engine Fixing Bolt" (bolt through the bottom of the frame through the
bottom of the engine) is seized...got one nut off, the other close to rounding it before I stopped. Have used
liberal penetrating spray (Blaster is the name of it). I tried pounding it through but am concerned about
wrecking the cases the bolt goes through. ANY SUGGESTIONS? I took off the front and back engine mounts
and tried lifting the engine to take stress off the bolt...nope. I put the front and back engine mounts on
and tried pounding the bolt out...nope...at a loss at this point. Any tricks?

Thanks!

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Re: New owner of 71 Thunderbolt with question [Re: VANDOLSON] #711110
10/10/17 4:01 pm
10/10/17 4:01 pm
Joined: Jul 2001
Posts: 12,899
Central Virginia
Lannis Online content

Life member
Lannis  Online Content

Life member
Joined: Jul 2001
Posts: 12,899
Central Virginia
If you could get the swingarm pivot out (which is something that most of us cannot do without torches and hydraulic presses!) you'll figure out the engine mounting bolt. That bottom one is always the worst because it's the one most slathered with road dirt and corrosion.

Since the bolt goes through the engine cases and the frame bosses, and since the frame bosses "protect" the cases from twisting and breaking under pressure, I think you'd be safe in (A) trying to get some sort of anti-corrosion 'stuff' in there, like a 50/50 mix of ATF and acetone and (B) patiently "pounding", using some mechanical sympathy but being firm about it, until the corroded-in-place bolt moves. If the steel bolt is in fact "welded" to the aluminum cases so that it won't come out this way, you're looking at a machine-shop repair anyway, so it's worth a try. (Says me who has no skin in that game!) I'd also try a heat gun liberally played on the cases until they're too hot to touch where the bolt goes through, and then whack it .....

You said a mouthful when you said "The engine is fine". To me, the only way I could make that statement is if I was in personal contact with an engine rebuilder of KNOWN competence (and this wouldn't include people who might be experts on Triumphs and Sportsters and small-block Chevys and therefore don't know how to clean a sludge trap, line-ream a crank bushing, or shim the crank end-play), who has given you every detail of what he did to this motor, and you believe him .... If I didn't have all that, the motor would be coming apart down to the crank ....

Good luck with it all! They make nice-riding bikes when you're done, and generally the only one on the block ....

Lannis


I stopped believing for a little while this morning. Journey is really going to be upset.
Re: New owner of 71 Thunderbolt with question [Re: VANDOLSON] #711112
10/10/17 4:50 pm
10/10/17 4:50 pm
Joined: Sep 2017
Posts: 65
Windsor, Virginia, USA
V
VANDOLSON Offline OP
BritBike Forum member
VANDOLSON  Offline OP
BritBike Forum member
V
Joined: Sep 2017
Posts: 65
Windsor, Virginia, USA
Thanks! Heat is next. After that, going keep soaking
with penetrating spray for a few days and try again.

Re: New owner of 71 Thunderbolt with question [Re: VANDOLSON] #711113
10/10/17 4:50 pm
10/10/17 4:50 pm
Joined: Feb 2008
Posts: 4,387
New Jersey USA
Tridentman Offline

BritBike Forum member
Tridentman  Offline

BritBike Forum member
Joined: Feb 2008
Posts: 4,387
New Jersey USA
First of all--welcome to the forum--and congratulations on staying with a bike!
Not a bad choice of bike and don't worry about paying "too much".
As you say it is a hobby and no bike has a "right" price decided by someone who has not bought it.
Only the buyer sets the "right" price for that bike in that place at that time.
Ref the engine mounting bolt---no short cuts IMHO.
Use plenty of PB Blaster, use a lot of heat as the crankcases are real heat sinks and use force.
Ref force--no gentle taps or even repeated hard thumps but rather a really good whack with a lump hammer to really shock the corrosion between the aluminum crankcases and the steel bolt--which is holding it in.
HTH and best of luck!

Re: New owner of 71 Thunderbolt with question [Re: VANDOLSON] #711114
10/10/17 5:04 pm
10/10/17 5:04 pm
Joined: Nov 2010
Posts: 3,035
Arlington, Massachusetts, USA
kurt fischer Offline

#irideslow
kurt fischer  Offline

#irideslow
Joined: Nov 2010
Posts: 3,035
Arlington, Massachusetts, USA
Another "welcome" to the forum. Paid too much? Spending too much? "haha" is all I can say, and don't worry about it. I'd be lucky to recoup half of what I've got in my bikes grin

I really like my '71 Lightning. To paraphrase what Lannis said, it's not a Triumph.


Kurt
1968-70-71 Triumph TR6R Bitsa - 1969 Triumph TR6R - 1971 BSA A65L - 1973 Triumph TR5T
2005 Ducati MTS 1000S DS - 2012 Ducati Hyper 796 - 2014 Kawasaki ZX1000
Re: New owner of 71 Thunderbolt with question [Re: VANDOLSON] #711117
10/10/17 5:54 pm
10/10/17 5:54 pm
Joined: Sep 2017
Posts: 65
Windsor, Virginia, USA
V
VANDOLSON Offline OP
BritBike Forum member
VANDOLSON  Offline OP
BritBike Forum member
V
Joined: Sep 2017
Posts: 65
Windsor, Virginia, USA
Whew! Got it out! Laid the bike on its primary side on a
carpet. Took my mapp gas torch and heated the bottom
engine cases and frame. About 5-min of heating. Was
able to drive it out. Lots of rust and bits came out
with it!!

Hope the case bonding is okay (no leaks).

The engine. Not a novice to bike engines and engine
rebuilding. Usually restore bikes back to all oem
condition with NOS parts. Last one was a Harley
1981 FXS Lowrider. Complete frame/engine build.
Sold to a motorcycle shop in Japan. Was in the
window of his shop in fact (got pictures) to draw
In customers. I did the whole restoration myself.
Not doing so with this BSA.

I guess I am saying that after riding the bike and
listening to it with my stephoscope I am real comfortable
with the engine as it is. I would not have bought it
If the engine in my opinion was bad or needed work.

Hopefully I am correct......I could eat my words in the
future...hah!?

Lannis, thank you so much for replying to my issue!
many thanks! Applying Heat was correct. It was going
to be my last option anyway. You saved me time and
cases by bringing it up.

BTW, I hate typing on my iPhone.....

Best Regards,

"Van"

Re: New owner of 71 Thunderbolt with question [Re: VANDOLSON] #711129
10/10/17 8:07 pm
10/10/17 8:07 pm
Joined: Aug 2001
Posts: 4,004
argyll. scotland, uk
gavin eisler Offline
BritBike Forum member
gavin eisler  Offline
BritBike Forum member
Joined: Aug 2001
Posts: 4,004
argyll. scotland, uk
Congrats on the bolt removal. heres a coup[le of tips for the 71.
Its maybe too late , but the bottom mount has a steel spacers between the frame and motor, if there is anything left of it make a note of the thickness and what side it was on, its easily lost / forgotten, but it stops the frame springing and helps keep the vibes down.

if you are going to repaint the steel side covers , have a good look at the inside top edge, as stock they interfere with the coil brackets, causing beakage and vibration, the inner top edge can be scalloped about 5/16 " to prevent rubbing off the coil bracket. Best to test fit and adjust before painting.
It took triumph till 1973 to scallop them at the factory.

The air box lids centre mount is not easy to use as stock, the airbox inner can be fitted with a 5/16 UNF helicoil , makes bolting them back on a lot easier.
HTH

Last edited by gavin eisler; 10/10/17 8:08 pm.

71 Devimead A65 750
56 Norbsa 68 Longstroke A65
Cagiva Raptor 650
MZ TS 250
The poster formerly known as Pod
Re: New owner of 71 Thunderbolt with question [Re: VANDOLSON] #711131
10/10/17 8:10 pm
10/10/17 8:10 pm
Joined: Sep 2017
Posts: 65
Windsor, Virginia, USA
V
VANDOLSON Offline OP
BritBike Forum member
VANDOLSON  Offline OP
BritBike Forum member
V
Joined: Sep 2017
Posts: 65
Windsor, Virginia, USA
I hope I did not come off sounding pompous or a know it all or anything like that with my last reply...not
meant to.

I will say I did read all of the 611 posts on this BSA forum before I introduced myself. Learned some good
things! Years of BSA knowledge here and everyone seems great!!

Thanks everyone! Engine is out...learned in a few posts that you can remove the engine from the frame
by laying it on the primary side and lifting the frame off the engine....worked like a charm. I am going
to put the engine back in the frame that way. Good stuff here!

I continue to learn about BSAs...I never knew BSA owned Triumph...I thought Triumph owned BSA
in the 60's/70's. VERY interesting. What I like about my BSA is....none of the bikers today (unless
you are older) even know what a BSA is.

In the middle 70's I rode with 10 Triumph riders and 1 BSA rider. We hung out together as the Harley
guys didn't want to be seen with the "slimy limeys" as they called it. My 1965 TR6 blew away most of the
Sportsters back then though...hah!

I was never a fan of the OIF Triumphs when they came out. I thought the OIF 1971/1972 BSAs looked so
much better. I joined the Navy (late in life...I was 23 at the time....Nuclear powered fast attack submarines)
and made it a 20-year career. Once I got to my first submarine, I bought a 1975 Sportster and then owned
Harleys after that. However, I ALWAYS had a LOVE for the British motorcycles...dunno why...just thought
the engines were beautiful looking and just classic! Great to be back!

Thanks again to all, looking forward to learning more on this forum from the great people here.

Best,

"Van"

Re: New owner of 71 Thunderbolt with question [Re: VANDOLSON] #711210
10/11/17 4:42 pm
10/11/17 4:42 pm
Joined: Jan 2004
Posts: 3,757
ca, us
D
DMadigan Offline
BritBike Forum member
DMadigan  Offline
BritBike Forum member
D
Joined: Jan 2004
Posts: 3,757
ca, us
When taking the lower engine bolt out, leave the front bolt in, remove the rear bolts/plates and use a pry bar or wood wedges to lift the weight of the motor off the lower bolt.
You can fix the side cover bolt by adding a snap ring on the outer side of the bolt from the inner case. That will keep the bolt head from pushing in past the cast-in shoulders.
At least put an oil pressure gauge on it to test the hot pressure then you can go back to just the light.

Re: New owner of 71 Thunderbolt with question [Re: VANDOLSON] #741865
07/14/18 6:03 pm
07/14/18 6:03 pm
Joined: Sep 2017
Posts: 65
Windsor, Virginia, USA
V
VANDOLSON Offline OP
BritBike Forum member
VANDOLSON  Offline OP
BritBike Forum member
V
Joined: Sep 2017
Posts: 65
Windsor, Virginia, USA
Update. Well after reflection, took engine apart. Glad I did. Lots of rust?! Speedo that didn’t
Work had a little over 13K miles. Thought no way. I went ahead and did a total rebuild. Almost
New everything. So I eat my previous words about the engine. Interestingly still standard bore
And pistons. Mic’d everything. Bored 20-over now. Found that the head had inserts for the
Rocker cover studs but not 5/16 UNC for the head. It was UNF. Couldn’t use stock studs
(5/16 UNC for head and UNF for rocker nuts). Had to buy 2” 5/16 UNF studs.

I really wanted to restore the bike to NOS as much as possible (like running the stock
Points, zenior diode, rectifer, condensors, and so on). Had to replace the AAU as it was
Worn and pitted (found NOS....$200). Bought NOS contact breaker, NOS Zenior (tested),
NOS Rectifier, and new condensors, coils and alternator. Also bought NOS wiring harness.
LOTS OF MONEY for all. Now I decided to keep the bike and not sell it. So bought
A Pazon surefire IG and Podtronics regulator/rectifier. Sheesh more money. Not going
To chop up the NOS wiring harness so bought a new UK made harness. More money.
Also bought a SRM oil release assembly and new AMAL Concentric carb with the upgraded
Slide and float. More money. Hah!

So much for not touching the engine. Man was I so wrong! Guess I am going to sell
All the NOS ignitionl/electronic parts I bought to recoup some money.

Besides that I wish I had got the crank balanced. Completely slipprd my mind until
After I completely put the engine together. Sheeeesh. Almost tempted to tear the
Engine back apart. Anyway just an update. Will have parts for sale listed on this
Forum.

Re: New owner of 71 Thunderbolt with question [Re: VANDOLSON] #742076
07/16/18 7:32 am
07/16/18 7:32 am
Joined: Jan 2014
Posts: 3,884
Aus
N
NickL Offline
BritBike Forum member
NickL  Offline
BritBike Forum member
N
Joined: Jan 2014
Posts: 3,884
Aus
The '72 head has 5/16UNF bolts on the outer 4 rocker cover.
Only the '71 used 5/16UNC studs with UNF nuts. Prior to that they were 1/4 BSF.
The centre ones are both BSF/CEI studs.

The cylinder head/barrel fixings didn't change they are 3/8 BSF studs with CEI nuts.
The centre bolt has a reduced head on a 3/8BSF bolt i think.


The most useful modification is to fit an oil filter.


Lamas are bigger than frogs.
No room for sanity here.
Re: New owner of 71 Thunderbolt with question [Re: NickL] #742145
07/16/18 7:57 pm
07/16/18 7:57 pm
Joined: Sep 2017
Posts: 65
Windsor, Virginia, USA
V
VANDOLSON Offline OP
BritBike Forum member
VANDOLSON  Offline OP
BritBike Forum member
V
Joined: Sep 2017
Posts: 65
Windsor, Virginia, USA
Originally Posted by NickL
The '72 head has 5/16UNF bolts on the outer 4 rocker cover.
Only the '71 used 5/16UNC studs with UNF nuts. Prior to that they were 1/4 BSF.
The centre ones are both BSF/CEI studs.

The cylinder head/barrel fixings didn't change they are 3/8 BSF studs with CEI nuts.
The centre bolt has a reduced head on a 3/8BSF bolt i think.


The most useful modification is to fit an oil filter.


Thanks! When I bought the bike the owner added a Small red Purolator oil filter
Using a big c-clamp around the lower oil in the crame downtube. Not bad. Not
Really hanging down far and easy access. I drew out how he had the oil lines
Routed/attached before disassembly. Figure I would use that (new filter though)
Unless someone has a better setup/filter they recommend.

Best Regards

Re: New owner of 71 Thunderbolt with question [Re: VANDOLSON] #743109
07/25/18 2:55 pm
07/25/18 2:55 pm
Joined: Mar 2007
Posts: 249
Richmond, VA
tg4360 Offline
BritBike Forum member
tg4360  Offline
BritBike Forum member
Joined: Mar 2007
Posts: 249
Richmond, VA
Pictures... where are the PICTURES!

smile


'68 B25 Starfire (single)
'72 A65 Thunderbolt (twin (I'm sensing a pattern here..))
'78 XS750 Triple (Because I just can't get my hands on
a Rocket Three...)
'87 K100GS (four banger (Because NVT gave up too quick..)

Moderated by  Allan Gill, Jon W. Whitley 


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