bike strands me after 10 minutes of riding

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kevbo82

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Finally got my commando all together and ready to ride yesterday, take it out twice today and both times it died and left me on the road. 73 750, everything freshly rebuilt. Power arch ignition with full old britts kit (coil,plugs,wires,etc) brand new amal premiers, new petcocks, "rebuilt" fuel lines. So i can start and ride the bike no problem, after about 10 minutes on the road it starts to sputter and stalls. at that point i can start the bike back up, and it will idle just fine, but as soon as i touch the throttle it sputters, backfires, and stalls. The first time i limped home, and i saw a tiny bit of something floating in the fuel line. So i took the lines off, cleaned them out, took all the gas from the tank and cleaned the tank out, pulled the pet cocks and cleaned the screens (tiny bit of stuff on them) put it all back together and put new clean gas in, took it out. ran great. for 10 minutes. Same thing happened. this time i pulled over. Sat there for a half hour till the bike cooled off, started it up and raced home with no problems. To me this sounds like an ignition problem because it seems to only happen when things are hot? anyone have any other ideas?
 
one other thing i also noticed, a lot of air bubbles in the fuel lines. They seem to be traveling up towards the petcocks. But while sitting around for a half hour if i tapped on the fuel lines i got a lot of little bubbles and a few big ones too. don't know how normal that is.
 
kevbo82 said:
So i can start and ride the bike no problem, after about 10 minutes on the road it starts to sputter and stalls. at that point i can start the bike back up, and it will idle just fine, but as soon as i touch the throttle it sputters, backfires, and stalls.
Click to expand...

That sounds like fuel starvation?

Have you checked the fuel tank cap vent is clear?
 
Maybe you are operating the choke backwards? This happens pretty frequently with new Norton owners. The choke is off when the choke slides are pulled up - cables taut. Some say the way the lever operates is counter intuitive but I think it is intuitive. :)

Russ
 
L.A.B. said:
kevbo82 said:
So i can start and ride the bike no problem, after about 10 minutes on the road it starts to sputter and stalls. at that point i can start the bike back up, and it will idle just fine, but as soon as i touch the throttle it sputters, backfires, and stalls.
Click to expand...

That sounds like fuel starvation?

Have you checked the fuel tank cap vent is clear?
Click to expand...
That's what I thought at first. I did clean the cap, but I also tried to run it with the cap open and that didn't improve things. The fact that it acts fine after letting it cool down makes me think ignition though
 
I would start with checking the fuel delivery rate and go from there. That's easiest.

Dave
69S
 
concours said:
Screens in your fuel taps clogged with crap?
Click to expand...
They had a little bit on them, nothing crazy. When I get home I'll post a pic of the banjo filter which was about the same level of crap on it. If it was a fuel delivery why would the problem go away when I let it cool down?
 
batrider said:
Maybe you are operating the choke backwards? This happens pretty frequently with new Norton owners. The choke is off when the choke slides are pulled up - cables taut. Some say the way the lever operates is counter intuitive but I think it is intuitive. :)

Russ
Click to expand...
I'm not that bad Russ! I also think its backwards, I think when the choke is off the lever should sit parallel to the bars
 
kevbo82 said:
concours said:
Screens in your fuel taps clogged with crap?
Click to expand...
They had a little bit on them, nothing crazy. When I get home I'll post a pic of the banjo filter which was about the same level of crap on it. If it was a fuel delivery why would the problem go away when I let it cool down?
Click to expand...

What do the plugs look like? Black and sooty? Clean and near white?
 
If your carb are tickling up nicely then the floats are usually not too low.
May not be a fual issue. Sputter, cough, stop. Sounds like a loss of juice to me. When setting for 10 minute or so, this will allow the battery to recover enough to start up and run till discharged again. Your battery may be good because of the seemingly recoverability. However, you better do the dance and find out for sure.
Try these things:

1. Either weak battery, load test it out of the bike.
(more than likely)

2. Charging is insufficient, check voltages DC at battery at different rpm to start with. If no change is present at rpm changes, check AC output before regulator from stator leads. If AC voltage is present then bad reg/rec. If no AC voltage, then bad stator or broken/bad leads.
(Definitely possible)

3. High load present. DC amp probes are not too common so check for a large drop in voltage when lights are turned on. Troubleshoot and isolate if needed. This scenario would also include a bad switch.
(not likely, but possible)

Check all your connections and remember, the stator feeds the battery and the battery feeds the load (ignition, lighting, switches, etc).
 
Here's what one of the banjo filters looked liked. The screens on the petcocks pretty much looked the same. Cleaned everything, reassembled, rode great for 10 mins then cut out again. Let it sit for a half hour then rode 5 mins home with no problems.

bike strands me after 10 minutes of riding
 
pvisseriii said:
If your carb are tickling up nicely then the floats are usually not too low.
May not be a fual issue. Sputter, cough, stop. Sounds like a loss of juice to me. When setting for 10 minute or so, this will allow the battery to recover enough to start up and run till discharged again. Your battery may be good because of the seemingly recoverability. However, you better do the dance and find out for sure.
Try these things:

1. Either weak battery, load test it out of the bike.
(more than likely)

2. Charging is insufficient, check voltages DC at battery at different rpm to start with. If no change is present at rpm changes, check AC output before regulator from stator leads. If AC voltage is present then bad reg/rec. If no AC voltage, then bad stator or broken/bad leads.
(Definitely possible)

3. High load present. DC amp probes are not too common so check for a large drop in voltage when lights are turned on. Troubleshoot and isolate if needed. This scenario would also include a bad switch.
(not likely, but possible)

Check all your connections and remember, the stator feeds the battery and the battery feeds the load (ignition, lighting, switches, etc).
Click to expand...

I was starting to wonder about the battery. I bought it from interstate last march when I started working on the bike. I've been using a wicked smart charger and it seemed to think the battery was ok. I think I'll get into it a bit more cause I know the electronic ign like a lot of juice
 
I was starting to wonder about the battery. I bought it from interstate last march when I started working on the bike. I've been using a wicked smart charger and it seemed to think the battery was ok. I think I'll get into it a bit more cause I know the electronic ign like a lot of juice
Click to expand...


seems odd that bike runs for 10 minutes and shuts off, then regenerates and runs again

put a volt meter on your battery and take a reading

then turn on the headlight and keep it on for three minutes and take another volt reading

report back here?
 
1up3down said:
I was starting to wonder about the battery. I bought it from interstate last march when I started working on the bike. I've been using a wicked smart charger and it seemed to think the battery was ok. I think I'll get into it a bit more cause I know the electronic ign like a lot of juice
Click to expand...


seems odd that bike runs for 10 minutes and shuts off, then regenerates and runs again

put a volt meter on your battery and take a reading

then turn on the headlight and keep it on for three minutes and take another volt reading

report back here?
Click to expand...
Ignition off the battery showed 12.57V, key on and low beam headlight left on for 3-5 minutes battery showed 11.91V
 
We've designed a "standardized home test" for battery testing. First, completely charge your
battery and reinstall it in the motorcycle. With the engine not running, turn ON your lowbeam headlamp for 2 minutes. Your battery voltage may start out fairly high. After 2
minutes, with the headlamp still ON, take a voltage reading across the battery terminals.
Most average batteries will be somewhere around 12.3V after the 2 minute time period, but
results will vary depending on the condition of your battery. As a part of normal battery
aging, a chemical change takes place inside the battery that raises the internal resistance and
thereby lowers the available voltage. Your reading could be anywhere between 7.0 to 12.9
volts. A higher reading would indicate a battery in better condition.
If you had an electronic ignition (a Boyer) you must have a reading above 12.0V or replace
the battery. This is because a Boyer’s circuits absolutely will not function below 12.0 volts.
I
Click to expand...

http://www.gabma.us/elec/battery_testing.pdf
 
kevbo82 said:
If it was a fuel delivery why would the problem go away when I let it cool down?
Click to expand...
Because the time lets your float bowls fill up again. Like I say, check the simple stuff first, fuel is easy and sounds like a good possibility. The other things are harder to check. Take off the line at the bottom of your petcock and see how much fuel comes out in say one minute. I remember someone had a list of how much the Amals need in a given time while running strong.

I never had any dirt in any of my screens, if I did, I'd be worrying. F/G tank.

I know the BAP taps I have put out a whole lot less fuel than the originals did. I was a bit concerned about it, but they work.

Don't start with the long hard involved things first. You'll be kicking yourself in the butt. Not to say it couldn't be something else though.

Dave
69S
 
DogT said:
kevbo82 said:
If it was a fuel delivery why would the problem go away when I let it cool down?
Click to expand...
Because the time lets your float bowls fill up again. Like I say, check the simple stuff first, fuel is easy and sounds like a good possibility. The other things are harder to check. Take off the line at the bottom of your petcock and see how much fuel comes out in say one minute. I remember someone had a list of how much the Amals need in a given time while running strong.

I never had any dirt in any of my screens, if I did, I'd be worrying. F/G tank.

I know the BAP taps I have put out a whole lot less fuel than the originals did. I was a bit concerned about it, but they work.

Don't start with the long hard involved things first. You'll be kicking yourself in the butt. Not to say it couldn't be something else though.

Dave
69S
Click to expand...

+1.. do a volume test on fuel tap.
 
IF it was a lack of fuel to the carbs problem, then please explain how the bike can run "just fine" for ten full minutes in the first place?
 
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