A trick for starting after carbs taken off?

My 'new' '75 MK III had been starting and running pretty good the couple weeks I've had her, and I decided to remove the clunky airbox and install a basic slip-on filter. Got it all back together, and it won't run. It will fire a few times, but won't continue. For the balance hoses that came out of the intake manifold and went to the oil-vent separator apparatus (or whatever it was), I just used a length of hose to connect the 2 manifolds together. I try starting both with the choke on (cable all the way in), and off. It's not cold here in SC. The ticklers always produce a dribble of fuel.

I figured I must have messed something up when I had the Amal carbs off, so I took them back off, disassembled them (all new jets, it looks like, 220 and 106 if I remember correctly), blew compressed air through all the orifices, and reassembled. I looked for any electrical connections I might have knocked off (only found one empty connection, but saw nothing to connect it to), and I sprayed electrical cleaner in both ends of the coil wires (also look new) and made sure they were seated properly. Same deal; no start-up. It won't even fire when just kicking, but the starter will always get a few bangs before it stops. I tried brand new spark plugs.

I'm thinking now that it must be a coincidence that it wouldn't start after I put it back together; maybe an electrical component (coil?) is checking out?

What ignition system?? State of charge of the battery??

Check for spark. remove the sparkplug on one side and then re-attach the high tension lead. keep the plug grounded to the head and kick it over while checking for a spark. Key on. If you got IE as in Boyer then just hit the kill switch with the ignition key in the on position. Or just turn key on then off to see if it sparks the plug. this will eliminate if its gas related or electrical.
Cheers,
Thomas

Engine kill switch (right side handlebar) in wrong position ?

It's easy to knock the clip off the jet needles when you have the carbs off, then it will have the symptoms you mention.

Had the exact same thing happen to me! The bike just would not start!
I tried and tried even went so far as to jump start it down our hill. Nothing worked.
Retraced everything I touched and discovered the clip had come off the needle.
Fixed the clip back and Boom...Fired right up!
Good luck.

Float levels?

Just read Bushman's tutorial on cleaning an Amal carb and was about to try the guitar string through the pilot jet tip, when I read the post above about the kill switch. DOH! With a queasy feeling I went out and checked, and sure enough! DOH! And I regularly teach MSF classes, where I often have to tell students the same thing! Oh well; she started right up. Odd that it would fire a couple times (when using the starter), even with the kill switch off... Oh well, time for a penance ride. Now I just need to figure out how to secure the side panel (I hadn't realized it was the airbox that the panel attached to until the airbox was removed). Thanks for all the suggestions.

oediehl said:

Odd that it would fire a couple times (when using the starter), even with the kill switch off...

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Does it still have the original points ignition? As that can be a feature of the original ignition system because the ignition is powered directly from the battery (via the starter solenoid and white/purple ballast bypass wire) and not through the normal ignition circuit whenever the starter motor is in operation.

oediehl said:

just need to figure out how to secure the side panel (I hadn't realized it was the airbox that the panel attached to until the airbox was removed).

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You can buy a ready-made airbox replacement bracket (link, below) but if you make a bracket, do make sure the panel will be securely attached as the battery covers were often lost, also the Mk3 battery covers (both Roadster and Interstate types) are different from previous Commando models so replacements can difficult to find.

http://www.oldbritts.com/13_066330b.html

L.A.B. said:

oediehl said:

Odd that it would fire a couple times (when using the starter), even with the kill switch off...

Click to expand...

Does it still have the original points ignition? As that can be a feature of the original ignition system because the ignition is powered directly from the battery (via the starter solenoid and white/purple ballast bypass wire) and not through the normal ignition circuit whenever the starter motor is in operation.

Click to expand...

Mine fooled me exactly the same way before I took the points off. The bike would fire as long as the starter was operating, but shut off instantly when the starter button was released .... It's a shame that the kill switch isn't designed to kill that eventuality too ... if you're new to the Norton, you'd never figure to look for the kill switch as an issue when the bike is firing and then cutting off ....

Lannis