New and having some trouble...

Hello,

I recently bought a 73 Commando on a whim and I love it! I don't know much about mechanics, but I am slowly learning. I eventually would love to completely understand how everything works and how to fix the problems.

Tonight while I was riding, I was making a u-turn and the bike stalled on me. I was on the side of the road kick starting it and after about 15 tries it fired up and immediately died. The indicator light on my headlight turned on and off a few times. I kicked about 5 more times until it started and I kept revving it because it would die once I engaged the clutch. So I rolled away and the bike started to jerk every few feet. I tried to see if second gear was any better and it just became too rough. I safely made my way home only less than a mile away. I filled up my tank right before this happened, but do not if the fuel I used could have caused this. Any ideas what the issue could be? Thank you guys.

Blocked idle jets in the carbs (will not run under 2000 rpm)
Unscrew horizontal air crew in each carb, poke through jet buried about 7/8" in with 1-1/2" length of 0.016 wire, blow through with air.
Drain carbs (drain screws?) and clean tank. Fit see through inline filters if tank is rusty and monitor.
Preferably pull the carbs and clean properly (lots of Youtube an Amal cleaning) but in the meantime see if this works.
Screw idle air screws back in, gently bottom and unscrew 1.5 turns.

Fractured wire on electronic ignition (if you have this) making intermittent contact (less likely if it ran ok at higher revs), or any fractured ignition/power wire with an intermittent fault. I had the positive cable fracture at the batt terminal a few years ago but it was kept in contact by the routing and bend in itself, only vibrating open circuit as the revs changed.

A battery that is failing will also cause these symptoms, especially with electronic ignition. Do a quick load test. Charge battery and take a reading with a volt meter across terminals. Turn bright light on for two minutes without starting bike.
Take another voltmeter reading. Should only drop a volt or so.
Water in the gas can also cause this. Open the float bowl drains and catch what comes out in a small container to see if any water present.
Remove a fuel line at the carb and check for fuel flow.

Also check the vent on the gas cap. If it is blocked, it will cause a vacuum that does not allow gas to flow to the carbs. A quick test would be to open the cap and start it. See if you can ride it any distance without it stalling.

Just a thought, as you are new to Commandos I will state the obvious:- the handlebar choke lever needs to be pulled to lift the choke slides up out of the way in the carburettors once the engine is warm (the opposite to a car's choke lever which is usually pulled to engage the choke). Rough running will occur if this is not done as the engine mixture will become too rich.

after it sits and cools down does it start/run normally or still sputter?

kevbo82 said:

after it sits and cools down does it start/run normally or still sputter?

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Good point, could be a bad coil that is failing when heated.

When troubleshooting, if it looks like a fuel issue it is probably electrical and vice versa. :twisted:

drones76 said:

kevbo82 said:

after it sits and cools down does it start/run normally or still sputter?

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Good point, could be a bad coil that is failing when heated.

When troubleshooting, if it looks like a fuel issue it is probably electrical and vice versa. :twisted:

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yeah i usually associate problems while hot with electrical, and fuel problems at least seem to stay consistent in a perfect world... :roll:

Welcome shortshort, please tell us more about yourself. What's your mechanical ability level? consider yourself a shadetree? Have you ever heard/read about suck/squeeze/bang/blow ? List some previous mechanical acheivements... auto repairs, bike repairs. etc. You own a DMM? With this starting point we'll be better equipped to give you news you can use.

Try Avgas .

Do a wiggle test on the wire harness. I had the same thing happen but it was a loose connection at the ignition switch. For a couple of weeks I was chasing fuel problems that didn't exist.

You guys are all so awesome. I am proud to be a Norton Owner. I hope I can get this issue resolved soon.

kevbo82 said:

after it sits and cools down does it start/run normally or still sputter?

Click to expand...

This morning the bike started for a second and died. I think I am going to have a mechanic look at it soon. I know I need a new chain but that shouldn't effect the engine.

concours said:

Welcome shortshort, please tell us more about yourself. What's your mechanical ability level? consider yourself a shadetree? Have you ever heard/read about suck/squeeze/bang/blow ? List some previous mechanical acheivements... auto repairs, bike repairs. etc. You own a DMM? With this starting point we'll be better equipped to give you news you can use.

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I do not know anything mechanically. I don't know about suck/squeeze/bang/blow. I am starting to teach myself. Any info or video tutorials would help! Thank you!

Where in the world are you? Can update your profile?

Perhaps someone is nearby to take a look?

swooshdave said:

Where in the world are you? Can update your profile?

Perhaps someone is nearby to take a look?

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+1 If you take it to a mechanic they are going to do their best to separate you and your money. Whether your bike actually gets fixed is coincidental. Let us know where you live. There's probably a Norton Owners Club somewhere near by. They work for nothing and they get a kick out of doing it. This is just a few of the chapters.

http://www.inoanorton.com/Chapters/index.html

rpatton said:

swooshdave said:

Where in the world are you? Can update your profile?

Perhaps someone is nearby to take a look?

Click to expand...

+1 If you take it to a mechanic they are going to do their best to separate you and your money. Whether your bike actually gets fixed is coincidental. Let us know where you live. There's probably a Norton Owners Club somewhere near by. They work for nothing and they get a kick out of doing it. This is just a few of the chapters.

http://www.inoanorton.com/Chapters/index.html

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Cool! I am in Northern California. I will def get in contact with someone around here! Thank you!!!

What Wes and me by far get show stopped from then usually going again, once we learned the Commando ropes and rules, If it sounds like fuel, smells like fuel and acts like a fueling fault > check the 'lectrics first... after dark, at home, recommended.

beefco » Mon Mar 25, 2013 4:03 pm
Do a wiggle test on the wire harness. I had the same thing happen but it was a loose connection at the ignition switch. For a couple of weeks I was chasing fuel problems that didn't exist.

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Ditto battery mentioned and its terminals and the charging wires and kill switch corroded, all at once is entirely possible, plus a fuse that looks good but ain't, so find and fix one obvious fault then still have same symptoms, Btw after a fouling episode its common for the plugs to begin fouling so always have some new ones to try plus some more news ones to try as its well known every now and then there's a bad plug right out the box that can drive you to torch a great bike if only the owner can get up to speed.

Oh yeah I had one saga of exact same symptoms once, in worsening cycles, miss firing to stall,then no fire to start, then suddenly it would and run enough to tease me but soon as it felt surface moving it'd miss fire intermittent or just go out. Tail light woven ground strap inside the bulb holder bouncing to short out. You do know copper breaks inside our insulation w/o showing up but wire by wire tests, or just pulling and tugging in frustration till you create something obvious to fix and feel better knowing ya did that one right the first time...

Some day grease the Amal slides to see if they seal well or not - but regardless soon enough they will not, so shop now for anodized slides to preserve carb bores while ya can. Zinc oxide forms the crust that clogs the pilot jet, so solvents don't touch it, only mechanical clearing or mild acid bath boil work.

ever since owning a norton i don't remember what suck, bang, blow is. My wife's still pissed about all the money spent on the damn bike :shock:

kevbo82 said:

ever since owning a norton i don't remember what suck, bang, blow is. My wife's still pissed about all the money spent on the damn bike :shock:

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Nortons can be wallet vacuums. Especially when the owner is convinced he can turn a 40 year old motorcycle into a modern sport bike. If you spent less than a CNW rebuild I guess you are ahead of the game. I see some uninitiated, new owners that have totally unrealistic visions of what Norton ownership costs. Those cool looking, shiny, upgraded, great running Nortons that grace the pages of this forum have cost the owners well into 5 figures.

You said you were making a u-turn and the bike stalled on me...my bets on, water in the tank.