choke query

by **brf1957** » Sun Jan 24, 2010 12:37 pm

Hi all, My mk1 will only run with choke on, as soon as i put choke off bike just cuts out even after warming up ,can anybody tell me what i should be checking for Brian

by **Gino Rondelli** » Sun Jan 24, 2010 12:41 pm

Brian, Maybe sounds daft but are you putting the choke "On" rather than off. The Amals chokes are ON when you release the choke , pulling the cables up takes the choke off. I've found that the choke makes little or no difference on Commandos even in our winters and usually remove them totally, relying on the ticklers for starting.

by **mikegray660** » Sun Jan 24, 2010 12:47 pm

brf1957 wrote:Hi all, My mk1 will only run with choke on, as soon as i put choke off bike just cuts out even after warming up ,can anybody tell me what i should be checking for Brian

what kinda of carbs would help a bit....

by **brf1957** » Sun Jan 24, 2010 12:58 pm

Hi sorry mike carbs are standard mk1s

by **brf1957** » Sun Jan 24, 2010 1:06 pm

Hi Gino, yes definitly working choke the correct way ,i know what you mean about removing chokes i chucked them a long time ago on my trident and just use ticklers starts great ,being new to nortons i was going to leave them on as my mate was telling me his mk3 wont start without choke so will wait and see , Brian

by **mikegray660** » Sun Jan 24, 2010 1:30 pm

brf1957 wrote:Hi sorry mike carbs are standard mk1s

do you have any history of the bike running proper with the carbs that are on it now ? usually if it will only run on full choke there is an air leak ( loose and retighten / check all carb/head fittings) , or if bike has been sitting for a bit the old gas may of gummed up the pilots ( remove carbs and carb cleaner the jets/passages)
both easy to do - would be the first place i would start - also have you changed plugs - (probably not it but always good to start off w/ good plugs)

by **Cookie** » Sun Jan 24, 2010 1:56 pm

If they both were dead after sitting one might expect gummed pilots wouldn't you?

by **brf1957** » Sun Jan 24, 2010 2:23 pm

Hi, no i dont know how it was running before ,i know it was laid up for about 3 years, i had carbs ultra sound cleaned , maybe need to put them through again will check again tomorrow for air leaks etc thanks for advice

by **L.A.B.** » Sun Jan 24, 2010 3:05 pm

brf1957 wrote:i know it was laid up for about 3 years,

Brian,

I think we need a bit more information than you have given us so far?

OK so you've had the carbs cleaned.

Is the fuel new?

Are the plugs new?

Did you check...

The float heights?
The ignition timing? (and gaps, if points ignition?)
Valve clearances?
Compression?
Air filter?
Is the balance pipe between the intake manifolds leaking or split (or missing?).

What are the pilot air screw settings?
Does turning the throttle stop screws inwards by a significant amount help to keep the engine from stalling?

by **brf1957** » Sun Jan 24, 2010 4:03 pm

Hi LAB yes fuel is new, plugs new , float height set , timing strobed to 31 degrees as it is running with boyer , tappets set ,new air filter , balance pipe ok ,air screws 1-1/2 turns out ,only thing i havnt checked is compression , and screwing up throttle stop screws, Brian

by **Gino Rondelli** » Tue Jan 26, 2010 3:08 am

Brian
Easiest way to check for manifold leaks is to get it started then spray WD40 liberally over the manifolds and listen for a change in engine note.

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