Hard starting when warm,low electrical output when idling.

jamesp · Aug 17, 2011

Hello, I am new to this forum, just purchased my first Norton, a 1974 Commando, a few weeks ago. I love the bike, runs great, lots of power and good handling. My problem is that it is hard to restart after it warms up. When cold, tickle the carbs, starts on no more than three kicks without the choke. When warm, I have tried all methods that I can think of from priming the carbs, to not priming the carbs, to closed throttle, to partially or fully open throttle. After about 10-15 minutes of lots of kicking and sweat, it will restart. I don't know if I am doing something wrong, just don't know its proper technique, or maybe there is something mechanically wrong with it. Any suggestions would be greatly appreciated. Also, I have noticed that the turn signals and lighting system do not function well unless the revs are up. Is this normal? Thank you for any help on these topics.

maylar · Aug 17, 2011

Re: Hard starting when warm,low electrical output when idlin

What kind of ignition system to you have? One of the most popular electronic ignitions (Boyer Mark III) does not like low battery voltage, so those two symptoms may be related.

The stock electrical charging system leaves much to be desired, and with headlights on at low RPM the battery is required to take all the load. A well maintained battery is a must.

jamesp · Aug 17, 2011

Re: Hard starting when warm,low electrical output when idlin

Thanks for responding. It has the stock points set up. I have a Boyer ignition that came with the bike, but never installed. I still need to go through the bike, setting valves,checking timing etc., but it runs good when it starts, except for some exhaust popping on deceleration, so I did not think it is tune up related.

Flo · Aug 17, 2011

Re: Hard starting when warm,low electrical output when idlin

Could be your ignition timing is retarded.
Idle mixture maybe slightly out.
Have you tried starting with throttle closed. My 750 will not start with any throttle at all.

MEHAVEY · Aug 17, 2011

Re: Hard starting when warm,low electrical output when idlin

Low[er] Voltage when idling is normal (How low?)
I will always have red assimilator light staring at me below 11-12 hundred RPM

Otherwise

COLD: Choke ON
Flood Carbs YES
Throttle BARELY open (I can't over emphasize this)

LUKE WARM:
Choke ON
Flood Carbs NO
Throttle 1/8 open

WARM/HOT:
Choke OFF
Flood Carbs NO
Throttle 1/4 open

jamesp · Aug 17, 2011

Re: Hard starting when warm,low electrical output when idlin

Thanks, I have tried with throttle closed and various openings, but usually always flood the carbs. Maybe that is the problem? On one occasion, I pulled the plugs, they looked dry. I dribbled a little gas in, replaced the plugs, and it fired up. I will try not flooding and using some throttle on my next ride, see if that works. Thanks, again.

Hobot · Aug 17, 2011

Re: Hard starting when warm,low electrical output when idlin

Sound like worn slides adding to symptoms too similar to mine on a new rebuild but 8000 mile old Amals. I must tickle to drip, then 1/4 throttle for a few kicks when hot. Otherwise w/o the tickle she fires a few times too weak to start which seems to suck gas out lower to need flooding and more throttle and few more kicks ugh.
I've had 3 Nortons that started 1st kick for long intervals, so just know that's the normal to seek. I've ordered anodized slides and hope the bore aren't beat up too much too. In mean time I'm gonna try grease to seal slides and see if that works till dissolved away. If starts well cold pretty much implies plugs and timing adequate.

jamesp · Aug 17, 2011

Re: Hard starting when warm,low electrical output when idlin

Ok, I see what you are saying. If slides are too loose, suction will not pull gas from float bowl. That could explain why my plugs were dry after a round of fruitless kicking. My bike has over 19,000 miles. I will check with previous owner to see if any work done on carbs. He told me he never had a problem starting when warm and that I just needed to find the right combination. How can you tell if slides are too worn? What are the ways to solve that problem? Thanks.

jamesp · Aug 17, 2011

Re: Hard starting when warm,low electrical output when idlin

I called Rabers in San Jose, Ca. They suggested that if slides are bad,tickling carbs would give it enough fuel to start if compression is good, which it is. He suggested I carry extra spark plug to check spark when cranking, to see if any shorts are developing while it is getting hot.

Jeandr · Aug 17, 2011

Re: Hard starting when warm,low electrical output when idlin

There is also the possibility of a bad coil breaking down when hot, nothing else to do but try a new set which is probably cheaper than buying just one and trying to find the bad one (if it is bad of course)

Jean

pete.v · Aug 17, 2011

Re: Hard starting when warm,low electrical output when idlin

Batteries in these bikes need to be fresh, robust, and often need supplemental charging. That just life in the Commando world.

BrianK · Aug 17, 2011

Re: Hard starting when warm,low electrical output when idlin

FWIW, popping on deceleration means your idle circuit is too lean. A bit more fuel/less air will alleviate this.

Whether that helps your hot starting problem is another question (it may or may not...how's that for taking a stand?), but it's worth doing in any event.

Please report back! Best of luck.

AussieCombat · Aug 17, 2011

Re: Hard starting when warm,low electrical output when idlin

G'day James,
They're a tempremental thing.
Does yours idle nicely when cold, or take a long time before you can let go of the throttle.
If it idles nicely from a cold start then it might be a little rich, but that's not a bad thing.
If it won't idle for quite a while, it might be a little lean.
Mine likes plenty of throttle to start, hot or cold. Probably 1/2.,
If you still have the original twist grip, (throttle hand piece), you will notice it is a very slow action,
so to give it half throttle means a considerable turn.
Keep playing, you'll find a way.
AC.

roqueweiler · Aug 18, 2011

Re: Hard starting when warm,low electrical output when idlin

I had this problem last year on my "new" Commando.

Here's what I did:

new battery and solid state voltage regulator

this solved a lot of kicking and frustration
(although it still will not keep up to the loss of voltage from running the headlamp while riding.
I charge it at least overnight after a few days riding. The horn is a good indicator
of whether or not you have sufficient voltage in the system while riding, at least on mine)

When warm, here's how I start
tickle ONE carb, doesn't seem to matter which
kick through once or twice easily
(or turn with your superhuman hobot like arm)
turn on ignition
kick and thorottle up when it starts

Good luck

Hobot · Aug 18, 2011

Re: Hard starting when warm,low electrical output when idlin

OHHHhhhh, roqueweiler - now I get it, give one carb a richness dose and the other leave in lean-ness so the fickle gals should choose at least one to fire then the other, cool. Definitely will try this, after new anodized slides installed in a few days. I'm not up to arm wrestling Combats for a hobby but could be given enough brew to try it at a rally , Hey watch this ... what could go wrong? Really though even Combats should be pussy cats to start then roar like a Tiger with just a wrist flick, ahhhh.

jamesp · Aug 18, 2011

Re: Hard starting when warm,low electrical output when idlin

Thank you for all the good tips and suggestions. I need to go through the bike's systems and make sure it is in good tune, including adjusting the carbs. When not being ridden, it is on a battery tender to keep the battery up. I believe the battery is in good condition. The carbs were rebuilt by the previous owner, not exactly sure how much was done to them, but I will be seeing him tonight, and will try to find out. Rabers gave me name and number of someone who re-sleeves them, just in case. Next time I try to restart when warm, I will try some of your suggestions, including checking my spark to see if any open circuits are developing when it gets hot. I'm thinking that might be it, because it runs so well when started.

Hard starting when warm,low electrical output when idling.

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