Help with troubleshooting

I recently picked up a 72 Commando, my first exposure to a British bike. When I took it out for my first ride, within a mile or two it began missing, and after a couple more miles returned home making it only by keeping the revs up. It would die if I pulled in clutch without revving up. When I pulled the plugs they were black and wet, so appeared rich. Removed carbs and found 230 jets and needle in bottom position. So went by book and replaced w 220 jet, new needle clipped at center position. Also replaced throttle cables and made sure they moved slides at same time when throttle turned. Set idle jet screws out 1.5 turns. So, trying to start for first time this afternoon running into issue. I tickle the carbs and it will start for 1 to 2 seconds and die. Although i can repeat it, it does best after tickled (choke has been removed on this bike). But, even after several try's when I tickle carb fuel immediately flows so bowl appears full. When it does rev I can usually get two revs and then it will die, sometimes backfiring. I've tried idle mixture screws in and out, but no real effect. The backfiring after revs makes me think a timing issue (has electronic ignition, not points), but it didn't do this before. Just looking for advice as to order of what I should look at. I love the sound and look forward to riding it, but must sort out this issue first. Thanks for you advice, Sid

I'm not going to say this is definitely going to be the cure but the first thing on any newly purchased Amal equipped British bike with running issues like this is to make sure the pilot circuit is not blocked and go from there.

Charge the battery.

And then when its running, verify with a multimeter that the battery is receiving enough volts from the alternator to charge it - and to keep the bike running.

If there are no volts coming out of the alternator, your troubles may all be electrical.

Remember, 90% of carby troubles are electrical, and 90% of electrical problems are likely to be carby !
This is a British bike, afterall....

I "think" I got the idle circuits clear. They had supposedly been cleaned before, and I went through it and carb appeared clean. May need to revisit.

The voltage on my battery is 12.4 volts. When I turn on ignition drops to 12.36. It doesn't run long enough to check alternator output. Probably a good idea to put on charger to tonight and make sure charge not an issue. Hadn't thought about that. Thanks.

Check for "sunken floats" ... Too rich, tickles immediately

Are you still trying to get it to run with the wet black plugs? Try a set of brand new plugs, see if it starts and runs at least as well as it did on your first run. If it acts the same way, just a couple of miles before acting up, check the condition of those new plug and if wet and black again in such a short time determine if the "wet" is oil or fuel. Keep some notes.

You have been advised to check battery, this is particularly important if you have Boyer ignition. Very sensitive to a drop of voltage and needs a good battery. Speaking from experience. If the battery is good, charge it, any doubts change it. If you don't you will have problems v similar to fuel starvation.

millersinhollis said:

72 Commando.......

Removed carbs and found 230 jets.......

So went by book and replaced w 220 jet,

Click to expand...

Does it have 932 (32mm) carbs?
Which "book" as the factory manual says: "230 (220 with mute)...Needle [clip] position: Middle (Top with mute)" for a "Combat" which your '72 model is likely to be, and if it ever had mutes fitted to the exhausts then it's unlikely they will be there now.

http://www.classicbike.biz/Norton/Repai ... mmando.pdf
pdf p.24


It's unlikely that main jets one size too big would cause such a severe problem in "a mile or two" and unless you had the throttle more than 3/4 open during that short ride the carbs would not be operating in the main jet range so I suggest you replace the 230s, at least for now.

https://www.oldbritts.com/amal_tun.html
http://amalcarb.co.uk/downloadfiles/ama ... _guide.pdf

millersinhollis said:

has electronic ignition,

Click to expand...

Which (make/type)?

I did not try new plugs but did clean the old ones. After trying to start I did recheck them and although a little black no oil or gas buildup like before.

The electronic ignition is Pazon, made in New Zealand. Have no clue whether this is considered a good brand or not.

I do have hopes the issue may be battery after reading feedback. When I went out in shop last night I hooked the battery tender up to bike. The 2 hours I was in shop the battery tender showed red light, which means it was charging but battery less than 80%. I checked this morning and it now shows fully charged.

I'm leaving for day to family gathering, but this evening when I return will give it a go and see if the battery being charged has resolved issue. Thanks to all.

millersinhollis said:

The electronic ignition is Pazon, made in New Zealand. Have no clue whether this is considered a good brand or not.

Click to expand...

Pazon is good.

millersinhollis said:

when I return will give it a go and see if the battery being charged has resolved issue.

Click to expand...

The battery going flat during a ride suggests the charging system isn't working, if that is the case then the problem may not have been resolved and will very likely happen again, so it's something that needs checking once you've got the bike running.

The battery going flat during a ride and the length of time it took to charge it could also suggest that the battery has some internal damage or is sulfated and is not taking a charge well. Charge the battery and record the volts, should be around 12.9 fully charged. Without starting the engine, turn the headlight and taillight on for 2 minutes. Check the voltage again. If it's dropped more than a few tenths of a volt the battery is toast.
The Pazon ei is an excellent system. I have it on 3 bikes. It functions best with at least 12 volts going to it. The symptoms of less than 12 voltss is very similar to what you describe. Hard to start and poor running at low rpm.
IMHO if the battery is over 3 years old and the lead acid type I would replace it if running ei. I've never had one last much over that on a Brit bike. The new AGM glass mat batteries seem to hold a charge better and no danger of acid leaks on chrome and paint.
http://www.ebay.com/itm/Motobatt-Batter ... 3K&vxp=mtr

Well, I didn't have any success with charged battery, but I'm going to just replace it so I have a known good battery since I down know age or history of one in it. I think there is another issue though. The charge light does not come on at all when I turn on key. I assume it should light and once the alternator starts putting out charge it should go out. It does nothing. I swapped bulb w flasher indicator bulb since it was working and still nothing. So, I need to do a little electrical 101 to learn how system works and then go through all my connections. I may have a bad ground somewhere. The electrical mods are not neatly done so could have grounding out, etc. I need to do some digging before I come back with questions. Thanks.

Don't forget that Commandos all come stock with a positive earth electrical system
= red wire to +ve earth from the battery.
It can play havoc if anything is reversed polarity - and not always immediately obvious.

Jist thought we should mention it....

Drop the bowls if concentric carbs and check if the Jet Holder is not loose. Your symptom sounds familiar what I experienced. I could be wrong. Yes check pilot jet for obstruction.

millersinhollis said:

Well, I didn't have any success with charged battery, but I'm going to just replace it so I have a known good battery since I down know age or history of one in it. I think there is another issue though. The charge light does not come on at all when I turn on key. I assume it should light and once the alternator starts putting out charge it should go out. It does nothing. I swapped bulb w flasher indicator bulb since it was working and still nothing. So, I need to do a little electrical 101 to learn how system works and then go through all my connections. I may have a bad ground somewhere. The electrical mods are not neatly done so could have grounding out, etc. I need to do some digging before I come back with questions. Thanks.

Click to expand...

the warning light is an indicator only [ worked by the expensive assimilator which can be replaced with a 5 terminal on off relay. see previous post. ] and wont stop the bike charging if the system is ok. Ie if you rev the bike with a volt meter across the battery terminals and you get 14.5 volts or so then all might be ok there. OR, if you rev the bike and the lights get brighter, you have a good idea that the bike is charging. You have mentioned the battery has 12 + volts in it, so if it stillhas 12+ volts when the ignition is on, that is possibly telling you the battery is ok, and should not stop the engine going.

Dereck

Possibly ok is not the same as OK. A battery can be toast and still show 12+ volts with the ignition on. That is not much draw. Turn on the lights, turn signals, put on the brake and then measure how many volts the battery has.