Fastback 1970 mk2 specifics

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Thomasdunstall

Thomasdunstall

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Hi can anyone post some picture of a 1970 Fastback Mk2?
Better if unmolested during the years, I would like to check the correct parts on it.

My VIN number is 1397XX

I know it should have upward angled reverse cone mufflers. Oil tank is the square iron 1968-70 type and left side panel is fiberglass and without rotor lock assy.
I would like to know if it was the original fitment or not the (1971 type) modified stand, chain guard and alloy hand levers.

Many thanks in advance
Thomas
 
Scanned from 1970 Brochure...

Fastback 1970 mk2 specifics
 
edit: model year 71 started with 141900?
Then at 141783 I call them S2A-1 started

I too would like to see a later genuine 1970 series 1 fastback.

The pix shows what I would have expected: ampmeter, fastback oil tank, large diameter fork gaiters, chrome rear shock covers, steel oil pipe to head
The marketing pix does not show front yellow reflectors and red rear reflectors?

craigslist:
ZENER on LH Z plate ? correct? none on RH side.
 
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If it has the large fastback oil tank as per brochure photo then it should have the matching steel side cover on the LH side with the rotor lock.1971 Fastbacks had the later tiangular oil tank, a fibreglass bolt on cover,the matching LH side cover also in fibreglass is held on by the Dzus fastener plus the grommets at the rear,also had tool pocket inside the cover.The 71 also had the dodgy side stand too,held only by a circlip.
Brett
 
Rosey
71 S 2A-1 is not in question and I agree with your description.
also:
The 72 FB are basically the same as 71 except disc brake, combat tune engine, and either fiberglass roadster OR fastback side covers. I've seen both type side cover but can not say the factory sent it out that way...

dynodave said:
I too would like to see a later genuine 1970 series 1 fastback.
Click to expand...

The Series 1 1970 Norton marketing pix is somewhat wonky. No front reflectors and from my observations the kick up bend of the upswept pipes is always pivoted below the kick start/clutch axle. I don't believe it represents production reality.

I'd prefer to see several real delivered hardware and try and determine what original was .
 
what I found:

side covers & oil tank

1968 to early 70 have the metal left cover with rotorlock and square oil tank

later 1970 fastback (mark 2 from engine 139571) are fitted a silver fiberglass left panel (but this is different from the black left panel fitted on the 71-72 fastback) and square oil tank

1971-72 black fiberglass side panels with roadster type oil tank

handlebar levers
alloy type with lucas switch introduced on 1971 model (I've heard some later 70 already fitted with alloy levers but had no confirmation)

chain guard
1968 to early 70 fitted with the black chain guard (I've heard some later 70 already fitted with chrome later chainguard but had no confirmation)

pipes & mufflers
1968 to early 70 fitted with low pipes & cigar type mufflers, later 70 already fitted with later upward angled reverse cone mufflers

frame
the mark 2 fastback end to number 141717 in january 1971 so it's likely that later Mark 2 were fitted with the 1971 frame and had different side and centre stands (centre stand fitted to the cradle not to the frame)

hope this could help
comments are welcome
Thomas
 
Thomasdunstall said:
frame
the mark 2 fastback end to number 141717 in january 1971 so it's likely that later Mark 2 were fitted with the 1971 frame and had different side and centre stands (centre stand fitted to the cradle not to the frame)
Click to expand...

The frame with cradle-mounted centre stand 'officially' began at 141783 (Fastback MkIII) in "January 1970" according to various sources including AN who sells the frame-mounted stand as "BEFORE ENGINE NO. 141783" and the cradle-mounted stand as "141783 ONWARDS".

https://andover-norton.co.uk/en/shop-details/15537

https://andover-norton.co.uk/en/sho...tand-06-3051-06-2192-engine-no-141783-onwards
 
Thomasdunstall said:
Hi can anyone post some picture of a 1970 Fastback Mk2?
Better if unmolested during the years, I would like to check the correct parts on it.

My VIN number is 1397XX
Click to expand...
You are trying to validate a series 1 rolling chassis with MKII fastback body style

Thomasdunstall said:
1968 to early 70 have the metal left cover with rotorlock and square oil tank
Click to expand...

A series one Commando rolling chassis had 2 different oil tanks 68-(70 partial?) used "fastback" and "S" because it was introduced with "S" also called by some as "central".
What you call a fastback MKII I suspect is still a fastback oil tank and a new fiberglass LH side cover to match the oil tank and the same attachments as the earlier MKI metal side cover. This does sound reasonable to me. Where did the key mount?
AGREE with LAB as stated above

Chrome chain guard like "S"/Roadster...possible ?
Thomasdunstall said:
pipes & mufflers
1968 to early 70 fitted with low pipes & cigar type mufflers,
later 70 already fitted with later upward angled reverse cone mufflers
Click to expand...
AGREE later series 1 rolling chassis and body work


The 141783+ Series 2A-1 rolling chassis with front cross bar-pin mounted side stand, and new front end... I would not believe it had a central oil tank.
I would believe a MKIII fastback would have a roadster oil tank and therefore new S2 compatible fastback side covers both sides until the end of fastback in 72. Agree?
 
This era had lots of changes for sure.
I am looking to find if my 13706X:
S1 Rolling chassis
20M3S drive train
The question is could it be either roadster OR FB...therefore when did FB change from 20M3 to 20M3S?
I have all the parts for either...:)
I know it could wear the "S" clothing but I'm not interested in this.
 
dynodave said:
You are trying to validate a series 1 rolling chassis with MKII fastback body style

A series one Commando rolling chassis had 2 different oil tanks 68-(70 partial?) used "fastback" and "S" because it was introduced with "S" also called by some as "central".
What you call a fastback MKII I suspect is still a fastback oil tank and a new fiberglass LH side cover to match the oil tank and the same attachments as the earlier MKI metal side cover. This does sound reasonable to me. Where did the key mount?
AGREE with LAB as stated above

Chrome chain guard like "S"/Roadster...possible ?

AGREE later series 1 rolling chassis and body work

The 141783+ Series 2A-1 rolling chassis with front cross bar-pin mounted side stand, and new front end... I would not believe it had a central oil tank.
I would believe a MKIII fastback would have a roadster oil tank and therefore new S2 compatible fastback side covers both sides until the end of fastback in 72. Agree?
Click to expand...

I'm asking if later 1970 fasback have different parts from the early 70 productiona...and what parts...maybe some of the 71 parts (as the chrome chainguard) were introduced with latest 70 model bikes? (I don't trust actual parts fitted cause I know in 50 years previous owners may change some parts)
I didn't consider the S/Roadster central oil tank, only talking about fastback model
No dubt about 71-72 production

thanks
T
 
dynodave said:
This era had lots of changes for sure.
I am looking to find if my 13706X:
S1 Rolling chassis
20M3S drive train
The question is could it be either roadster OR FB...therefore when did FB change from 20M3 to 20M3S?
I have all the parts for either...:)
I know it could wear the "S" clothing but I'm not interested in this.
Click to expand...

Dave is just to understand better...not looking for a concourse bike :) I use my bikes everyday and I want it easy, relaiable and confortable to ride
I will restore the bike as a 70 model with what I believe are the correct parts for a 70 model, anyway I will put the center stand on the cradle instead on the frame because it works far better...
 
Thomasdunstall said:
Dave is just to understand better...not looking for a concourse bike :) I use my bikes everyday and I want it easy, relaiable and confortable to ride
I will restore the bike as a 70 model with what I believe are the correct parts for a 70 model, anyway I will put the center stand on the cradle instead on the frame because it works far better...
Click to expand...

concours or not! My main concern is folks being able to reliably determine what "original" is and not trying to make anyone feel how they should build their bike. Cradle mount center stand certainly is better ...if the cradle can be modified to hold the centerstand and work?
The two S-1 frames I have are not put together enough to test this combination, so I will be interested to hear from you if it "works". Also hope you put a NONconcours oil filter LOL:)
 
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Thomasdunstall said:
ok thanks LAB
Click to expand...

dynodave said:
concours or not! My main concern is folks being able to reliably determine what "original" is and not trying to make anyone feel how they should build their bike. Cradle mount center stand certainly is better ...if the cradle can be modified to hold the centerstand and work?
The two S-1 frames I have are not put together enough to test this combination, so I will be interested to hear from you if it "works". Also hope you put a NONconcours oil filter LOL:)
Click to expand...

I agree in full Dave, this post has been done exactly to determine what original was on the 70 fastback model

Yes it works, already fitted a 71 centre stand to a 68 fastback and just works fine...

...and again Yes I will put an oil filter kit to the bike ;)
T
 
My hopefully last question for this thread is as follows:
As the fastback model progressed from "commando" to "fastback" MK1, so far, it was with a 20M3 drive train.
1. When, if known, when did the fastback drive train change from 20M3 to 20M3S by SN ?
It would have affected the wiring harness...
2. So therefore, was the drive train change at the same time (SN) as the change from MK1 to MK2 body style, stated as sn 139571 ?
Simple concept but I have not figured it out yet, and does anyone know ?
TIA
 
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dynodave said:
1. When, if known, when did the fastback drive train change from 20M3 to 20M3S by SN ?
Click to expand...

133668 according to various sources although there appear to be a few 20M3S Fastbacks with slightly earlier serial numbers.

dynodave said:
It would have affected the wiring harness...
Click to expand...

However, in spite of the change from 20M3 to 20M3S ignition plus the addition of the US only front brake light switch (which would have required an additional harness wire unless it had been there from the beginning?), and nothing to suggest the ignition condenser pack was moved from its original location so there was no apparent change of Fastback wiring harness part number (54954277) until Fastback MkIII as far as I'm aware.

Edit: "54956250 '69 - '70" listed by AN is the 'S' type (and '70 Roadster) harness in the '68 - '70 Commando parts book.


dynodave said:
change from MK1 to MK2 body style
Click to expand...


The significant change was Fastback MkIII (from 141783).
 
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Digging more in the historical items list in INOA tech digest

131257 first "S"
133688 first fastback 20M3S
135088 last "S"
quickly followed by first roadster 135140

137065 dd Series 1 for yellow roadster
141436 Ed's bike to be built as "S" clone

141783 first centerstand moved to engine plates = S2 type rolling chassis, maybe the factory records shows the body style actually built as fastback?

Back to work.:)
 
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