The Atlas Thread

Should a 1967 Atlas have an idiot light in headlight shell? Right now my 1967 has none but my stock 1966 has the idiot light..
 
Postby p400 » Wed Jan 28, 2015 9:52 am
What is the sprocket set on a 1967 Atlas? transmission/rear wheel?
5000rpm top gear equals 85mph

According to my Norton Owners manual (No publication date) the gear ratios for 750 and Scrambler (elsewhere I have read includes all heavyweight twins) are:
Engine Sprocket: 21 teeth
Top: 4.53, Third: 5.52, Second: 7.70, First: 11.6 to 1

My Atlas registers 70 mph on the chronometric at 4000 rpm. This would be 87.5 mph at 5000 and top speed of 119 mph.

The performance graph you posted seems a bit mild ...my Atlas would do 0-60 in under 5 sec.

Slick
 
Here's a picture of my '67- this is how I got it, don't know if it's stock, but I believe it is. It's the high beam indicator on mine (1967 originally w/ monoblocs & magneto)

The Atlas Thread
 
texasSlick said:
Postby p400 » Wed Jan 28, 2015 9:52 am What is the sprocket set on a 1967 Atlas? transmission/rear wheel? 5000rpm top gear equals 85mph According to my Norton Owners manual (No publication date) the gear ratios for 750 and Scrambler (elsewhere I have read includes all heavyweight twins) are:
Engine Sprocket: 21 teeth Top: 4.53, Third: 5.52, Second: 7.70, First: 11.6 to 1 My Atlas registers 70 mph on the chronometric at 4000 rpm. This would be 87.5 mph at 5000 and top speed of 119 mph. The performance graph you posted seems a bit mild ...my Atlas would do 0-60 in under 5 sec. Slick
Click to expand...

What I am after is the chain ratio for Atlas engine sprocket , clutch basket, gearbox sprocket, rear sprocket...............to compare to other 750 Norton of the pre Commando era. 21/42/19/42 ????
Reported speed , engine RPM, gear ratios are not making sense. Period magazine road tests appear to be fabricating tech information.


All of the Norton 750 clutch baskets are 42T.
All of the AMC 750 gearboxes (4 speeds 650SS, Atlas, N15CS, P11, P11A, G15CS, G15CSR, G15 II) are the shown with same gears listed for all boxes in spares list.
rear 750 sprocket appear, to me, to be 42T standard.
 

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P400 wrote: What I am after is the chain ratio for Atlas engine sprocket , clutch basket, gearbox sprocket, rear sprocket...............to compare to other 750 Norton of the pre Commando era. 21/42/19/42 ????
Reported speed , engine RPM, gear ratios are not making sense. Period magazine road tests appear to be fabricating tech information.

I cannot see my engine sprocket, but I assume it is 21 teeth per spec. (I am original owner and have not changed it)
I have 42 teeth on clutch: 43 on rear sprocket: 19 on gearbox sprocket. This works out to be 4.53 : 1 in top gear.

Slick
 
texasSlick said:
P400 wrote: What I am after is the chain ratio for Atlas engine sprocket , clutch basket, gearbox sprocket, rear sprocket...............to compare to other 750 Norton of the pre Commando era. 21/42/19/42 ????Reported speed , engine RPM, gear ratios are not making sense. Period magazine road tests appear to be fabricating tech information.I cannot see my engine sprocket, but I assume it is 21 teeth per spec. (I am original owner and have not changed it)I have 42 teeth on clutch: 43 on rear sprocket: 19 on gearbox sprocket. This works out to be 4.53 : 1 in top gear. Slick
Click to expand...

Thanks Slick, I get the same math, I learn sumpthin ever day. I thought the Atlas would be geared for lower rpm when touring than other 750 models ....maybe lower RPM leading to reduced vibration at tour speeds....but I find that is not the case. Based on this the Atlas would be "buzzier" than a P11.....not by much however.
 
Does anyone have measurements for dual monobloc carb Atlas throttle cables? I tried using a two into one Commando set-up but the two inner cables that go to the carbs are too long leaving a little slop in the outer cable and no adjustability. Specifically I'm looking for the measurement from inside one ferrule to the inside of the other ferrule. I'm going to have to do a little cutting and then put another ferrule on. Thanks.

Scott
 
Pull inner cable of jb to carb cable and measure from end of outer cable ferrule to end of inner cable..Mine is
3 1/2"....My throttle grip to jb cable was 3 1/8" from end of outer cable ferrule to end of inner cable...I made free play on that cable 2 5/8" and can adjust it now..
 
Thanks Beach.

Just for clarification, you did the measurement of the cable disconnected or with one end attached to the jb?

EDIT: What is the outer cable length as well? I think the Commando is about a 1/2" longer...
 
I measured both cables completely disconnected from carb, jb and grip...I had thought about making the cables from jb to carb each 1/2" shorter, but figured fixing the 1 top cable was easier than fixing the bottom 2...As matter of fact just finished this cable project last night..
 
Perfect, thanks Beach. Mine measure 3 3/4" of free cable. 1/4" of excess assuming the ferrules are the same length.

FYI... seems Commando cables are slight longer than the originals used on the Atlas with Monoblocs. You may get by if using Concentrics which is where I believe the difference lies in mix chamber lengths from cap cable seat to slide clip.

Scott
 
Got the longer Commando cables to work without modifying anything. I went to a bicycle shop with my cables, talked to the bike tech and went through his ferrules and adjusters until we found something to fit the cables. I used two adjusters that fit the junction, cut them off to take up my 1/4 slop, ground flats in the middle and put it together as shown. Now I got all kinds of adjustability.

Thanks all.

Scott




The Atlas Thread
 
While I'm on a roll with carb questions...

I got everything buttoned up but my 389's leak like a sieve. I figured out one issue, the second is the float chamber cover and banjo that goes around both main jet holder pour the gas out. They are tight, tighter than I would like and I'm using "Genuine AMAL Parts" seals, so what gives? Did I get some dried out ones? Anybody had this issue?

Scott
 
kernel65 said:
While I'm on a roll with carb questions...

I got everything buttoned up but my 389's leak like a sieve. I figured out one issue, the second is the float chamber cover and banjo that goes around both main jet holder pour the gas out. They are tight, tighter than I would like and I'm using "Genuine AMAL Parts" seals, so what gives? Did I get some dried out ones? Anybody had this issue?

Scott
Click to expand...

Do you have the fiber seals on each side of the banjo? Inspect the banjo surfaces and carb surface for nicks. The banjos should seal without much torque on the nut. You are right to suspect too tight means something wrong.

Slick
 
I got fiber seals on both sides and both are clean surfaces. I had to use two different kits, one (non-AMAL) had a little thicker seal than the other. I'm going to swap them and see what happens. I was hoping to fire it up this evening, but instead it seems to be Miller Time.

Scott
 
I have had continual problems with new fibre washers leaking. They are either made differently or they don't like whats in the fuel, do we really know what's in our tank's?.
 
Glad I'm not the only one, I'm thinking that taking them on and off for various reasons has caused them to become less effective. I did have them sealing up okay but as of this evening it is a different story.

I've been using ethanol free gas in all my bikes, I can only imagine what the corn gas would do. I've got some more washers coming so I'll see if that works.

Scott
 
norton bob said:
I have had continual problems with new fibre washers leaking. They are either made differently or they don't like whats in the fuel, do we really know what's in our tank's?.
Click to expand...

I use Dowty seals whenever I can. There are places one cannot use them due to the thickness of the Dowty vs fiber, the needle and seat of the float chamber being one such.

Here is a good source for Dowty seals. http://www.fittingsandadaptors.com ....Anyone have another?

Slick
 
kernel65 said:
Glad I'm not the only one, I'm thinking that taking them on and off for various reasons has caused them to become less effective. I did have them sealing up okay but as of this evening it is a different story.

I've been using ethanol free gas in all my bikes, I can only imagine what the corn gas would do. I've got some more washers coming so I'll see if that works.

Scott
Click to expand...

Copper ones are ok, and can be annealed when quashed.
 
Some Atlas 's have the fuel filler cap left of center, some right of center. Anyone know the rationale?

I have seen Atlas/Dommie tanks on flea bay both ways.

My '63 and '62 had the cap left...both were purchased in the US.

Slick
 
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