Norton Atlas with an offset crank

Interesting.

How do you do the ignition timing on one of these things? I was hoping he had a video on how to, but I watched 5 videos and ran out of time to waste.
 
Yeah! I read "Tuning For Speed" and have been intrigued by rephased cranks ever since. Enough to even go a little ways down the road of building a rephased Yamaha XS650 (not finished yet). Is there an off-the-shelf ignition system available for Nortons? What about the cam? (I admit I did not watch the video).
 
I beleive Pazon do offset ignition units. I'm sure knowing Andy he will be able to make something to suit.

Camshafts will be more of a challenge I expect.

But the big one I worry about with Nortons and offset cranks is harmonics in the cam chain drive. I'm interested in trying a 270 crank but anecdotally I understand they can be unreliable due to cam drive issues. . Very interesting in knowing some real experiences from anyone who has actually tried it.
 
Mind you, is that Atlas actually: 'offset?' (as per the second vid, 'desaxe' no?), or just no longer 360 degree?
 
The term "offset" is ambiguous. We have a staggered or rephased crankshaft, and an engine design providing a desaxe layout.
I read somewhere the Atlas engine is of small desaxe design, the figure is -0.093" (yes, negative), a result of some development shortcuts, and too small to be of any significance.
An intenional desaxe layout is found in the AMC lightweights, G2 and G5, which were good performers in their day.

These staggered crankshaft show-offs are tiresome to look at. Let's have a review of the real thing!

- Knut
 
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I think that for a FACTORY to produce a 270 twin makes sense. They will put in the necessary R&D into balancing etc. They will also have the equipment to make the cams without issue etc.

But when a DIYer does it, I tend to think that the the amount of opportunity to get such things wrong, or at least sub optimal, must go a long way to undoing the whole point.

And also, I’m just biased, I just prefer the nice crisp sound of a 360 degree Brit twin. When people say ‘it’s great, it’s like a v twin’ I always think, well why not just buy a v twin then ?!?
 
Fast Eddie said:
I think that for a FACTORY to produce a 270 twin makes sense. They will put in the necessary R&D into balancing etc. They will also have the equipment to make the cams without issue etc.

But when a DIYer does it, I tend to think that the the amount of opportunity to get such things wrong, or at least sub optimal, must go a long way to undoing the whole point.

And also, I’m just biased, I just prefer the nice crisp sound of a 360 degree Brit twin. When people say ‘it’s great, it’s like a v twin’ I always think, well why not just buy a v twin then ?!?
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I could not agree more, as the sound of a Commando running fluted peashooters is pure music. I did think about a 961 Norton a few years back, but the fact that it didn't have a 360 deg. crank put me off even though I love the sound of vee twins, & my Buell especially. There is no way I would change any of my Brit twins in this way. Other opinions are of course available.
 
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74ok said:
Prob see more of it down that road, certainly, the yam xs650 folks have already.
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What about the rationale? I miss an explanation in the presentations. It can't be a power surge - no one has yet demonstrated a rephased engine produces more power.
A little less vibration at high rpm's? Probably, if done right, but then, why are they constructing bobber bikes for around town riding? The original 180 or 360 degree engines were low on vibration already.
Constructing a rephased engine is no big feat in the case of an XS650. i wonder if the true motivation is a strange fixation for the V-twin sound only.

- Knut
 
Not sure if you are asking me specifically about presentation, rational etc, but for me, ended up seeing vids & stuff, new to me that i found interesting, so posted it

Then was aware that xs650 folks went there quite a bit, for whatever reasons, including various re-phasing angles, combined with power increases etc, my motivation is fwiw

then imo, it's inevitable that over time, others will go there with nortons
 
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