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650SS 1968 carbs and suspension and tyres new owner

Submitted by tom_steele on Wed, 17/08/2011
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Heavy Twins

Hi everyone hope you are all well,

young 22 year old here taking my first steps into working on my most treasured Norton 650ss :)

After getting a few parts for her to fix the tiny little things on it and just been trying to decide what fork internals to put on.

Pretty much decided on the hagon rear shocks with the black shrouds so they look pretty much original but with better internals than the standard ones, but am trying to decide between the Lansdowne kit and the Cosentino kit anyone used both or either? Read a few old posts on here but not seen any mention to the domi forks do know they both fit.

also carbs

Currently She's running a single 389 monobloc carb am after putting the twin carbs back onto the bike got the splayed manifold parts for the downdraught head and have been looking at the 930 Concentric Mk 1's but on the Amal site it lists two different carbs part no 930/17 and the 930/18 anyone know which ones it is for the 650SS? Or is one a right and the other a left? have actually got the other matched monobloc carb which I could rebuild what's everyone opinion monobloc/ concentric on the 650SS

tyres

Also, whats the sporty option tyre wise got some dunlop k (somethings on can't remember without going out to look at them)

Many thanks in advance and look forward to your replies,

Tom

Submitted by eugene_brolund on Wed, 17/08/2011

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Hi Tom,

great bike! Love the 650ss!

Tires: I like Avon, you can get classic treads, or sportbike treads, they seem to make them all! I run the Speedmasters on my '57 model 77, & used to run the modern Venoms on my '74 Commando.

See: http://www.avon-tyres.co.uk/motorcycle

Carbs: you may find this interesting, see the chart on page 2, *Number stampings: 930/7-8 means that left and right 30mm carbs will be stamped R930/7 and L930/8:

http://www.inoanorton.com/docs/TheNortonCarburetor.pdf

A single carb isn't a bad idea (GASP!) to consider as well (I like the Amal MHII Concentric), here are some thoughts from another very good forum "accessnorton.com" :

"I did some tests at N-V on a single-carb version of the Norton 650SS, which was my commute-to-work ride. We'd had some customer inquiries about the possible improvement to low-end torque with such a configuration.Tests showed that indeed an improvement on low-rpm torque did result, but that top end power was down about 12 percent. I rode the 650SS with the single carb installation as a commuter most of the time I worked for Norton-Villiers. Even with a daily commuter run of about 60 miles, I was hard pressed to tell the difference from the twin-carb set-up.I beleive N-V published the results of our tests, which were primarily of interest to people who used the Domiator and the Atlas as a sidecar hauler.I did some tests at N-V on a single-carb version of the Norton 650SS, which was my commute-to-work ride. We'd had some customer inquiries about the possible improvement to low-end torque with such a configuration. "

Frank Damp ex-NVT employee

Good luck,

Skip Brolund

Submitted by Xanna_jeannett… on Thu, 18/08/2011

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hello tom a Amal 930 is way to big for a 650 you need a pair of 28mm amal mk1 or amal 376 1/16th and the spacer is not splayed out there along side each other and tuning is not easy as you have too tune one carb at a time starting with the left hand one and take out the plug on the right hand side run the engine on the left hand side too tune that carb then do the same with the right hand side when you got both carbs something like then you hsve run it on both plugs is with rev like hell you now have to adjust the throttel side stops down untill the engine ticks over nicely , I think you maybe better of with the 389 , you get up too 110 mph anyway with twin carbs you get a another 8 mph out of it so way bother ?

Submitted by alan_dawes on Thu, 18/08/2011

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I am not getting involved in a "best carb" discussion as I haven't ever ridden a 650SS with other than the standard set up and my only experience with twin 930s was on my non standard and very fast (until the crank bust) Atlas. There are pages of interesting and frequently contradictory opinions on-line. Take your pick! Why do you have a splayed manifold on a 650SS?

As to tyres, my vote now goes to Avon Roadriders. Good performance, look OK, right sizes for Nortons available, not too expensive.

Cheers

Alan

Submitted by tom_steele on Thu, 18/08/2011

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Hi everyone thanks for the replys sorry If I said the wrong term regards splayed manifold I meant the bit between the original oval parts between the head and the carb as its got a 2 into one on it at the moment for the 389

might just spend the money on the suspension first and re address the carbs after some more thinking :)

thanks for all the advice and still got loads to learn :)

Thanks,

Tom

Submitted by Anonymous (not verified) on Thu, 18/08/2011

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Tom,

None of the replies so far has tackled the suspension questions. I have heard that the Cosentino conversion gives more limited fork travel and might be more suited to a racing environment. It is also expensive. I don't have any contacts who has this fitted and could provide a report but I think they have been tested in the USA by an NOC Member.

One reader of these message boards has fitted the Lansdowne conversion quite recently, and to a Dommie. I know he is still optimising the settings and also that he is away at the moment. Keep an eye on this thread and hopefully, he will be able to give some first hand information before long.

Submitted by tom_steele on Thu, 18/08/2011

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Ahh thats brilliant will do :)

Just got an email ofCosentino Engineering they've not done a 650ss before so thats narrowed the options down to the lansdowne kit if they don't fit got to check out if the dommi forks are 35mm? the overall extended length from the centre of the axle to the top edge of the fork tube and the size of the lower damper retaining bolt also if the threads in the fork tubes are the same as the commando ones? regards the Cosentino kit

many thanks Chris I will looking very forward to getting the suspension sorted before I start riding the bike which I am absolutely ecstatic about

just been watching the Mick Hemming's dvd's from the noc shop and studying the books Ive got all day really getting the norton lingo now

Thanks again everyone loving owning the norton and its most definatley one bike I will never part with

Tom

Submitted by neil_wyatt on Tue, 13/09/2011

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Just seen this. Following some good advice I'm putting a 30mm Mk 1 Amal on my 650ss.

I also went single carb on my 850 Commando a while back and it is much improved with fuel economy on 4* leaded up from 45 mpg to 68 mpg. The throttle is much lighter too with no more balancing acts....

A bit of atight fit with the carb on the commando but the slimline makes it a piece of cake for the 650ss. Single carb the way to go as we are only talking about a drop in the very top end.

As for suspension there is plenty of choice for the rear end, the front is the same as per Commando as far as the stanchion's and sliders go, though the Commando sliders are stronger and unlikely to be welded at the pinch bolt. You can buy them new! (Fork angle different on Commando so different yokes but both 7 3/8 from 64 on)

 


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