is a choke needed on a Norton commando??

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Could someone help me out>? The Norton shop I bring my bike to (way too often) claims that one does not need the choke for starting the carburator at cold start at all. )so they tightened the choke lever kinda shut). If that's the case, I will be happily agreeing to it. By why did the Norton factory purchase carburators that have a choke option and install a choke lever? I used to start my Norton with the choke lever fully closed and open the choke as soon as the engine started. ( I live in a rather cool climate of Alberta, Canada).
Can we just ignore the choke? Why?
Thank you for any feedback.

Josh in Calgary, Alberta, Canada
 
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I can't answer that. I can say that eliminating the choke is just one of the advantages of upgrading to Keihin FCRs (they use an accelerator pump - a few throttle twists does the trick when cold). Not to mention great response and power.

Bloody expensive though.
 
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Chokes aren't really necessary on Amal carbs in my experience. Half my British bikes have chokes and the other half don't. I have gotten used to slightly different starting routines with all of them. Chokes do help in getting the bike warmed up but you can start in cold weather by tickling the carb a little extra and turning up the idle screw for a few minutes.
 
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I use mine quite often, just makes it start better and warm up better in cooler temps...but now for the logic question. Why "deactivate" a usable choke? Stupid. If you want to use it sometime, it's not available and hasn't life taught us that "Never say never" is the way to go? That's like the guy that lives on a hill so he builds the starter out of his car to save weight. Whether you use the choke or not, personal preference...but I bet all of you who have removed their chokes, will at some time and place...wish you hadn't. That's one problem I won't have to worry about... :wink:
 

ntst8

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Needed no, i had Amals for 24 years with no chokes and with the ticklers there was never an issue starting in any temperature - incl after the bike stayed out overnight in 3" of snow, although that did take a few prods on the kickstart.
The down side was no idle on a cold engine. Of course being Amals there wasn't always a reliable idle on a warm engine either. :lol:
 
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If your carbs are in good nick and set up correctly you will need the choke for cold starting, if you don't there's something wrong. But if you're happy what the heck.

Cash
 
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You don't need a choke for cold starting, as you can dump raw gas into the intake track with the ticklers, if required. However, a choke does makes it easier to keep the engine running until its warmed up.
 

grandpaul

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I don't fully agree with the tickle-it-extra-rich crowd, as a fuel-fouled plug can and will wear out your kicker leg.
 
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On my 750, I find the choke is very useful for those first startups in the morning. I can get by without it in the summer but need it the other 9 months of the year.

Debby
 
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I've barely ever had a choke on either of my Nortons, (and neither has my friend got a choke on his either of his 920 Nortons) and never had any problems starting any of them with a good tickle, although my present Norton is always started on the electric option, and isn't easy on the kickstart for some reason :?:

The way I see it, which is probably different to a lot of other owners is, if the choke is definately clearing the venturi, and the choke bodies aren't slipping down slightly whilst the machine is in use, all well and good, but in the short time that I did run with a choke, on my Norton and and more recently, a Trident, it was always closing off slightly, and so I binned the choke, and have not regreted it once. Less problems, and less to have to maintain.

Just my opinion.........maybe it says more about my lack of ability to sort out a dodgy choke?
 
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choke needed on a Commando

I have a single 32mm carb. conversion on my 850, only on a 90 deg. day will the bike start without a choke.I don't need the choke on for long even on a cold Ohio Winter day,just enough to warm up the motor.Quote from Les Emery when I bought the conversion "If it starts without a choke -- and it won't -- there is something wrong". Over tickling the carb(s) will cause too much fuel to be drawn into the cylinders washing oil from the cylinder surfaces.Keep the choke, you may need it one day in Alberta!!.
Good luck. James.
 

L.A.B.

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ludwig said:
What is the choke closing that isn't allready closed by the the slide ??? . rough riding for the first 100 m or so , that I can understand , but NOT starting ??

As the choke valve is upstream of the throttle and jets, when operated that causes an intake airflow restriction, thus increasing the amount of vacuum (depression) above the jets. This extra depression draws up more fuel so enriches the mixture.

When the ticklers are used, that in itself probably provides enough extra enrichment for starting as the fuel level in the float chamber is raised, but once the engine starts that level will drop back to normal fairly quickly. If the engine has not reached a high enough working temperature by that time then the mixture may be temporarily too weak if there is no choke.



Let us also not forget that these bikes have had a "change of use" since they were first made? I doubt that many of them actually get ridden in either cold or sub-zero temperatures all that much,- if at all, these days? Many riders of that period would have expected chokes to be fitted, regardless of whether they used them - or not? I also doubt that buying carbs from Amal without chokes would have been an option for the Norton factory?


I agree with cash, if a stone cold engine will start with no choke and can be driven off in cold weather (that's less than 10 deg.C to me) almost immediately without any signs of weak running then it is almost certainly set up too rich.


"Plunger" chokes, as found on Amal MkIIs and Mikunis etc. work on a different principal to slide chokes by opening an additional jet (choke jet) to supply the extra fuel.
 

L.A.B.

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ludwig said:
This is only true wen there is airflow over the jets . With throttle fully closed , all air comes trough the pilot air circuit , wich draws its air BEFORE the choke slide . so the choke has no effect when starting with trottle fully closed .

Sorry but I disagree, as I believe the primary circuit would still be affected by the extra depression in the carb bore, and even with the throttle fully "closed" it isn't completely closed therefore as I see it, only a certain percentage of the airflow to the cylinder would be passing through the primary circuit?

If I had a just about any hot engine idling (throttle closed) and I applied full choke to it, then I would expect the engine show signs of richness and to stall, which would more or less prove the choke was affecting the mixture, - even with the throttle closed.
 
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I removed my chokes many years ago (can't remember on which advice but I must've read it somewhere). It seemed to me that the system of compressing and bunching a spring into the top of the carb was not helping throttle action and there were signs of wear inside the slide where the choke operated, again suggesting that it was causing friction.

With most motorcycles that use mixture enrichers, they are flicked off immediately upon starting and the machines operate satisfactorily. I'm always gentle on a cold engine anyway.

How far do choke users ride with the choke slide at full dangle and does it make any difference running with say 1/3 choke ?

My 850 runs standard jets and cutaways for the setup I'm using so any richness could only be on the pilot mixture screws (or possibly float level but mine take an age to tickle). I suspect that most old fashioned engines run more sweetly if they're a little rich off tickover anyway.

Mine starts from cold on a frosty day with just a tickle and I can't believe that it is so badly set up that it is running as rich as a well carburated bike on full choke.
 

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79x100 said:
With most motorcycles that use mixture enrichers, they are flicked off immediately upon starting and the machines operate satisfactorily.

My Mikuni VM carburettor-ed T160 would certainly be an exception to that rule, then! Not wanting to pull away at all with chokes off until it is very hot, so I normally have to ride off with two out of three chokes on.


79x100 said:
Mine starts from cold on a frosty day with just a tickle and I can't believe that it is so badly set up that it is running as rich as a well carburated bike on full choke.

I would however doubt that fuel metering of an Amal Mk1 carb is anywhere near as accurate as some modern carburettors?
I could only suggest that you try the same thing with a modern bike with modern carbs under those conditions and see what happens?
 
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Thanks for your thoughts L.A.B., If I think about it, all my non-Amal bikes have either been two strokes or had injection so probably not a fair comparison.

My comments about rich running were more intended to relate to a comparison with other Mk1 carbed Commandos where choke was needed.
 

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79x100 said:
My comments about rich running were more intended to relate to a comparison with other Mk1 carbed Commandos where choke was needed.

My own Commando doesn't need choke either!

But as we know with Nortons there's generally an exception to every rule!
 
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My71 750 S never needed choke to start (it was hard to start always) and the chokes made it worse, After rebuilding the carbs and new jets etc and a thorough clean out and retune it now starts first or second kick always . but only with the chokes on.Warms up in a minute and idles runs perfect. My carbie man tells me that they should be used and needed if the carbs are set up right or else it is running too rich from the outset., from my limited experinece this makes common sense to me. Why put them on if they arent needed. LAB makes a good point, theres a big difference between social use for 90% of todays owners than back when the bikes were every day essentials to get to the coal mines in winter sub zero England, I,m not sure of the quality of fuels available or ther bang for buck but i would think that they were nowhere near as refined as todays unleaded fuels ( good or bad i dont know) and this may have something to do with the starting charectoristics also
 
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