74 Commando left side pipe is cool to the touch (2009)

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74 Commando left side issues

daveh said:
What throttle opening are you using when starting from cold? I crack open the throttle about 1/8th, without choke, and it makes a big difference to easy cold starting. Having said that, I once had a partially blocked pilot jet on one carb, and it was hard to start from cold until I cleared it. BTW, have you checked your float levels?
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Hi Dave: I am also using about the same amount of throttle opening as you when starting, and no choke. Still takes 8 to 10 kicks to get it to run. On the 5th or 6th kick, it will start momentarily and run for a few seconds and then die. Finally lights up about kick number 10. When its warmed up one kick is all it needs, even if its sat for an hour or so after a run.
I did check float levels and found one initailly incorrect, and fixed it so I believe they are both right now, and not part of this problem. Good to know it was indeed a partially blocked pilot jet in your case. Thanks. Ted
 
How much do you tickle the carbs, to get mine going on a first or second kick from cold the petrol needs to be flooding out, if not its 7 or 8 kicks. I always find a fully shut throttle works best, you get the biggest draw on the pilot circuit that way. But bikes do vary so you need to experiment more.
 
74 commando left side cool to the touch

Hi Kommander: I usualy tickle the carbs till just the gaskets are wet with petrol. I tried flooding them a bit more till fuel ran down the bowls. and dripped down. Started in 7 kicks, no throttle.
At least that's better than 10.
Right you are, each bike is different in its own starting method.
Still more experimenting tomorrow after I delicately clean out the idle circuit. My #78 drill bit (.016") came from Grainger supply and I could hardly see it in the plastic bag, it's that small.
Why the lads at Norton would make that small an orifice, what with all the junk floating about in fuel beats me. maybe in '74 fuel was totally pure?
Must be some engineering reason they came up with.
I followed the different instructions about cleaning the circuit and have the bit nicely epoxied inside a tiny wd40 plastic spray tube ready to try an "easy fix" for that pilot jet with everything still on the bike..
 
Blame Amal not norton, but remember the oil companies make petrol for fuel injected cars not carbed bikes. Quads, lawn tractors with carbs all suffer too from blocked jets.
 
It took me a while to figure out the starting sequence for less kicks. I've found that my bike loves tickled, two prime kicks then another tickle and ignition and starts right up with no throttle. Then when warm it 98% hit's first kick.
 
74 commando left side cool

I did the idle circuit cleaning both sides, with the .106" drill bit.
No junk came out of the holes. and looked clean inside. Fired it up.
made no difference to the running of the bike.

Am I back to electrical?
I pulled left plug coil wire off, whilst bike is running and I do have a spark. It looks ok, but cannot tell if its strong . bike keeps running.
If I pull the right coil wire at idle, the bike dies instantly.
Not so at 3000 rpm and up.
I have swopped coils from side to side, no difference.
New coil wires, new plugs.
Checked the wiring diagram for the Boyer, looks correct.
Not firing on the left cylinder, at low rpm, or its only intermittently and/or weak. At 3000 rpm and up, it sems to be running fine on the road. and on the stand, and after a run, the left side header pipe is very hot. The left plug colour is a little lighter tan than the right, but looks ok.
Anybody clues.?
 
95% of all carburetor problems are electrical. More than likely you have a broken wire from the Boyer pickup plate. You will not see the break, it's covered by the insulation. Disconnect and check with an ohm meter. You have to wiggle the heck out of the wire. Better yet fix both now, as they will fail. The fix is to not solder the wire. Replace the connection with a crimped ring lug and small screw and nut.

BTW, was that a .016 drill as opposed to a .106? If you used the larger you now have a paper weight.
 
74 Commmando cool to the touch

Thanks to Jim C. for the Boyer details.
I did already have a broken wire when I got the bike in the Boyer and I did solder it back together.
Time to go back in there and check again.
Typo on the drill bit size it was the .016" number 78 that I used.
 
The drill bit alone is only going to work if the jet itself is plugged, it plugs first usually but the other passages can also be blocked. Sometimes carb cleaner and air can help, the best might be boiling the carb in distilled water.
 
74 commando left side cool to the touch

Hi Cookie, I can just see it, me boiling my Amals on the kitchen stove, wife comes home after work; " Hi Honey, guess what we're having for dinner?" Thanks for that tip. Teddy Boy.
 
On Goldwing carbs, arguably some of the most complex pains in the butt around to rebuild, Randak who is the recognised expert in the field cautions one to do this outside for domestic harmony.
 
&4 Norton left pipe.

Agreed, to maintain that state of matrimonial bliss, the Amal boiling should be out doors.
 
Have you tried Per's suggestion to hook up a strobe to each high tension wire? That could indicate if your problem is a poor spark at low revs. You could also try swopping high tension leads to check if one of the leads or plug caps is faulty. Have you checked the earthing of the Boyer? I discovered a bad earth there by running a wire from the Boyer directly to the battery earth terminal.
 
can you quickily change carbs side for side :?: and eliminate one item
 
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teddy boy said:
Bike takes 10 kicks when cold to start. Choke makes no difference.
Once warmed up starts instantly on one kick.
Rides fine @3200 rpm at 55 mph and seems to have decent power.
I can put my bare hand on the muffler on the left side and its not that hot. Installed 2 new exhaust pipes, right side turned a bit bluish right away, left side is still chrome out of the box. after 1000 miles.
Installed 2 new plugs and left side plug is whitish looking, whilst right side is correct colour.
I can cover left exahaust tip competely, bike does not stop running, even when revving on the stand up to 3000 rpm.
On the right, it tries to stall right away.
Pulled plug off from right side with lead attached, bike will fire on left side only, but barely idles. Looks like a decent spark on the left side.
Checked all elect. issues and valves. Boyer seems to be working ok, as do coils and all grounds. Cleaned both petcock screens.
Bike sat for 5 years with gas in it.
Am I thinking correctly it could be plugged idle jet on the left side?
Boyer hiding some other issue? Bad, or going bad cam on left side?
Click to expand...
If it sat for 5 years with the crappy gas we have now, remove the carbs and throw them away.
 
splatt said:
can you quickily change carbs side for side :?: and eliminate one item
Click to expand...
Clearance between the carb bodies may be an issue, the Amal bodies for Commandos are not symetrical side to side ,otherwise a good step in elimination .
Paul
 
Once again, please note this is a thread from 2009.
 
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