hi I have a recently fully restored commando Mk 3 On initial start up I cannot get the bike to idle I have new Amal carbs and original airbox The bike starts right up after tickling carbs but I have to stay on the throttle to keep it running. It is like the idle circuit in not working As soon as I back off the throttle the bike stalls immediately. I double checked the timing I am using a Pazon unit timing is dead on I thought maybe a bad battery and changed the battery The engine also surges as I am holding the throttle . Any ideas would be appreciated Thx Drummer 99
Commando 75 Mk 3 Wont idle
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Fast Eddie
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Are the new carbs premiers ?
cliffa
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Amal Premiers have been known to have machining swarf left it the idle circuit passages. So best advice is to remove them, then remove the pilot jet and idle airscrew and blow out the passages. Also it is now recognized that #19 pilot jets are better suited, so check what your carbs came with.
Mart UK
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My mk3 will not run without a light throttle until I've ridden about 400 yards. Start on choke, choke straight off, ride away. Once it starts to warm all is fine. Nature of carb bikes.
I once rode about 3 miles having forgotten to turn the choke off. New plugs and never did it again.
I once rode about 3 miles having forgotten to turn the choke off. New plugs and never did it again.
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As Mart says it will not idle when it is cold. There is no fast idle feature on Amal carbs when you use the so called choke as there is on most other carbs. You soon get used to it. It's not a great idea to start a bike from cold and let it sit idling anyway. Just start it when you are ready to go, and go.
Fast Eddie
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Good possibilities that are common and mentioned already:
Blocked pilot jets bushing, incorrect choke use, and the fact that failure to tick over nicely when cold is normal.
I’ll add two of my pet issues to the list of possibilities:
Duff spark plugs.
Out of sync slides.
Blocked pilot jets bushing, incorrect choke use, and the fact that failure to tick over nicely when cold is normal.
I’ll add two of my pet issues to the list of possibilities:
Duff spark plugs.
Out of sync slides.
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These are not EFI bikes, you tune them for operating temps which means they are not tuned to run well cold and you fudge it by tickling the carbs.
After sorting out the pilot circuits etc and balancing the carbs.
Tune it to run well when up to operating temps and when cold use the ticklers, in cold temps the choke will help but its only need for the first 1/2 to 1 mile.
After sorting out the pilot circuits etc and balancing the carbs.
Tune it to run well when up to operating temps and when cold use the ticklers, in cold temps the choke will help but its only need for the first 1/2 to 1 mile.
Fast Eddie
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Nothing is impossible of course, we all make mistakes! But assuming you followed the manual, or Hemmings video, or similar, getting the cam timing wrong on a Norton really isn’t very likely IMO (unlike Triumph).
It’s more difficult ensuring the slides are correctly synchronised than getting the cam timing right.
Not to hi-jack this thread, but how long should the ticklers need to be depressed to help the bike start cold? On my 750, it seems that just depressing them fully and then releasing them immediately, without really holding them in the down position for any length of time, seems to be enough to make my bike start (usually) cold. Sometimes on cold start up I use full choke, sometimes part choke, sometimes no choke and am still sorting out which seems to work best as I havn't started and ran this bike all that much yet. As others have said, carbed bikes need help on cold start up and I start my rider bike (old gold wing) on choke, when it starts, turn it to part choke and ride off, and as others have said in about 1 mile you start making some heat in the engine, turn choke off as you continue down the road.
trident sam
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The slides are not sitting at the bottom of the carbs and have a slight gap ?
Fast Eddie
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You simply hold down the tickler until petrol comes out of the little bleed hole and / or onto your finger. Some do seem to take longer than others.
Often that’s enough for these old bikes to start, many don’t run chokes at all.
The chokes in these things are really crude, they only really work when fully ‘on’ ie when the choke slide is all the way down. Having the choke half on doesn’t do anything for cold starting or running.
When you say many don't run chokes at all, do they (or can they) remove the choke slides altogether?
Tornado
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I've had my air control slides (ie choke slides) removed on my 850 since acquiring bike 7 yrs ago. No problems with colder starts, as many will also testify.
Avoids the not uncommon happenstance of the control lever slipping toward ON position while riding or worse, putting in ON (loose cable) due to misunderstanding how they work on these carbs.
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Tornado
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Other things to check, air leaks at carb flange to manifold, manifold to head. Do not over tighten card flange nuts, just past flattening of lock washers and no more, else risk warping flange, distorting throttle slide.
If not mentioned, is choke/air control slide in fully open position (tight cable)? How is fuel flow to carb from tank? Tank cap breather clear?
Check out the attached Bushmans Guide to Amal Tuning for all the tips and tricks sorting out these carbs.
I'll have to be the odd one out , as usual.
My stock MK3 will run very nicely right from cold startup as long as the chokes are on. It will idle smoothly and pull away easily with chokes on. It will rev high enough to accelerate reasonably thru the gears, maybe to about 3500 rpm in each gear. Above that it sputters because the chokes are on.
A mile or so down the road I pull the chokes off and it runs fine thereafter.
Old original Amals.
Not quite like a new efi engine but not far off.
Glen
My stock MK3 will run very nicely right from cold startup as long as the chokes are on. It will idle smoothly and pull away easily with chokes on. It will rev high enough to accelerate reasonably thru the gears, maybe to about 3500 rpm in each gear. Above that it sputters because the chokes are on.
A mile or so down the road I pull the chokes off and it runs fine thereafter.
Old original Amals.
Not quite like a new efi engine but not far off.
Glen
If I want smooth running when cold I'll use the chokes on the MK3 even on a warm summer day. They aren't needed for very long though.
I have other amal equipped bikes that have had the chokes removed. They require much more warm up before riding off and they won't idle until down the road a mile or two.
I might put the chokes back on those bikes one day.
I find that the way the MK3 works with the chokes fitted is just a bit more convenient, no need to blip the throttle when cold and no stalling while putting on gloves etc.
It's probably part of getting old.
Glen
I have other amal equipped bikes that have had the chokes removed. They require much more warm up before riding off and they won't idle until down the road a mile or two.
I might put the chokes back on those bikes one day.
I find that the way the MK3 works with the chokes fitted is just a bit more convenient, no need to blip the throttle when cold and no stalling while putting on gloves etc.
It's probably part of getting old.
Glen
