74 850 left me stranded

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RoadScholar said:
This is my guess as well; you said the bike died shortly after refueling. A plugged vent can cut off fuel flow in as little as 10 minutes with a full tank, longer with less fuel.
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The tank was full when I left, and it was over half an hour before the road failure including 25 miles at 65 mph. But I'm not ruling that out, and here's why -

After dealing with the kill switch and TriSpark issues the bike still wouldn't start. I put gas in the spark plug holes and it would fire for a couple seconds, but with the tank on it wouldn't start. Carbs would tickle OK and the plugs were wet. We had torrential rain for two days before and it was suggested (by my brother) that maybe the gas had water in it. Yesterday I drained the gas from the tank and put 2 gallons of hi-test in it. Viola, all is well again. Starts and runs normally.

That was the first time the gas cap was opened since the failure. If it is a plugged vent the problem will likely repeat. Is there a test for a plugged vent? And what's the cure?
 
maylar said:
The tank was full when I left, and it was over half an hour before the road failure including 25 miles at 65 mph. But I'm not ruling that out, and here's why -

After dealing with the kill switch and TriSpark issues the bike still wouldn't start. I put gas in the spark plug holes and it would fire for a couple seconds, but with the tank on it wouldn't start. Carbs would tickle OK and the plugs were wet. We had torrential rain for two days before and it was suggested (by my brother) that maybe the gas had water in it. Yesterday I drained the gas from the tank and put 2 gallons of hi-test in it. Viola, all is well again. Starts and runs normally.

That was the first time the gas cap was opened since the failure. If it is a plugged vent the problem will likely repeat. Is there a test for a plugged vent? And what's the cure?
Click to expand...
Disconnect one of the fuel tap pipes and run into a container
With the fuel tank cap on open the petcock
You should see a constant stream of fuel going into the container,not slowing or stopping
 
The vent is pretty obvious in this photo. Not sure if that raised portion is sealed from the actual mating face, so did wonder if a distorted seal (non OE or ethanol f*cked) could migrate and interfere with it??

andover-norton.co.uk

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maylar said:
The tank was full when I left, and it was over half an hour before the road failure including 25 miles at 65 mph. But I'm not ruling that out, and here's why -

After dealing with the kill switch and TriSpark issues the bike still wouldn't start. I put gas in the spark plug holes and it would fire for a couple seconds, but with the tank on it wouldn't start. Carbs would tickle OK and the plugs were wet. We had torrential rain for two days before and it was suggested (by my brother) that maybe the gas had water in it. Yesterday I drained the gas from the tank and put 2 gallons of hi-test in it. Viola, all is well again. Starts and runs normally.

That was the first time the gas cap was opened since the failure. If it is a plugged vent the problem will likely repeat. Is there a test for a plugged vent? And what's the cure?
Click to expand...
If you drained the fuel from the tank you can clearly see if there’s water in the fuel, it sinks to the bottom and has the appearance of being like ‘bubbles’ in the fuel.

It is because water sinks that it’s such an issue as that helps it to find its way to the petrol taps.
 
EstuaryBoy said:
The vent is pretty obvious in this photo. Not sure if that raised portion is sealed from the actual mating face, so did wonder if a distorted seal (non OE or ethanol f*cked) could migrate and interfere with it??

andover-norton.co.uk

Motorcycle parts and spares for Norton motorbikes - Genuine Andover Norton Spare Parts - Andover Norton Motorcycles Parts - Original Andover Norton Parts

Motorcycle parts and spares for Andover Norton motorbikes: Andover Norton manufactures and supplies all Genuine Factory Spare Parts for Norton motorcycles built before 2002.
andover-norton.co.uk
Click to expand...
Where does the other side of that vent hole go? It has to get to atmosphere somehow. And how would it get clogged if the cap never sees gas?
 
Fast Eddie said:
If you drained the fuel from the tank you can clearly see if there’s water in the fuel, it sinks to the bottom and has the appearance of being like ‘bubbles’ in the fuel.

It is because water sinks that it’s such an issue as that helps it to find its way to the petrol taps.
Click to expand...
I drained the tank into my lawn. it soaked into the ground and I couldn't really see if there was water left behind.
 
"I now have fuel and spark but the engine will not fire. Not even a pop. Put a charger on the Shorai, and called it a day. To be continued today."

Is the fuel getting into the cylinder, mixed at the right ratio?
Quick acid test: spray starting fluid into the air filter. If the engine pops a time or two, focus on getting gas in there.
 
concours said:
"I now have fuel and spark but the engine will not fire. Not even a pop. Put a charger on the Shorai, and called it a day. To be continued today."

Is the fuel getting into the cylinder, mixed at the right ratio?
Quick acid test: spray starting fluid into the air filter. If the engine pops a time or two, focus on getting gas in there.
Click to expand...
I did that. Gas in the spark plug holes and starting fluid in the air cleaner. Both were met with success (engine started). With the fuel tank in place the carbs overflowed normally on tickle and the plugs were wet. Conclusion is bad gas. Problem now solved.
 
maylar said:
Where does the other side of that vent hole go? It has to get to atmosphere somehow. And how would it get clogged if the cap never sees gas?
Click to expand...
The vent hole goes through the sealing plate , so it vents from under the top of the cap. sit on your bike with the stands up and rock it back and forth getting the gas sloshing around , and if you are in a quiet environment , you should hear pressure escaping from under the cap if your vent is working properly.
 
maylar said:
Where does the other side of that vent hole go? It has to get to atmosphere somehow. And how would it get clogged if the cap never sees gas?

Yes to above... Strangely enough, having just pulled mine apart, there is a similar hole on the opposite side, yet in no way are they connected. The hole shown, as stated above, vents peripherally, so it is possible a rotting seal could interfere with it's efficiency?...
Click to expand...
 
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maylar said:
Where does the other side of that vent hole go? It has to get to atmosphere somehow. And how would it get clogged if the cap never sees gas?
Click to expand...
Actually, two plates crimped together, each with a hole in the pressed ring that forms a gallery between the inner and outer holes that are out of alignment so acts as a 'baffle but it can become blocked with rust.

74 850 left me stranded

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74 850 left me stranded
 
Fast Eddie said:
If you drained the fuel from the tank you can clearly see if there’s water in the fuel, it sinks to the bottom and has the appearance of being like ‘bubbles’ in the fuel.

It is because water sinks that it’s such an issue as that helps it to find its way to the petrol taps.
Click to expand...
Long standing rules.

However, with the advent of ethanol blended gas, it is no longer true.
The ethanol emulsifies the water & it mixes with the gas. (Mostly, this is a GOOD side effect) So, the globular seperation we always saw is not a given any more.
 
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The ethanol is hygroscopic and combines with water. This is heavier than petrol / gasoline and sinks to the bottom. Unfortunately, if you decant off the water / ethanol mixture, you're left with petrol at a lower octane rating. The ethanol is a higher rating than the petrol and mixed to average out to the pump rating.
 
One thing to do is pull the drain plug on the carbs into a clear container. Yes old days you could see the water bubble like when you preflight an airplane. Now look for unclear petrol including micro dirt. Now that said it IS possible to get water stuck in the
jets and it takes a carb cleaner squirt to get it out. With ethanol maybe that too is history but drain the carbs.
 
Onder said:
One thing to do is pull the drain plug on the carbs into a clear container. Yes old days you could see the water bubble like when you preflight an airplane. Now look for unclear petrol including micro dirt. Now that said it IS possible to get water stuck in the
jets and it takes a carb cleaner squirt to get it out. With ethanol maybe that too is history but drain the carbs.
Click to expand...
I did drain the bowls. Didn't take the time to see if the fuel would stratify.
I'm certain that the bike will run fine now. My only concern is whether the tank vent is OK or not. Need to put some miles on it after topping off the tank.
Thanks to everyone for the suggestions.
 
maylar said:
I did drain the bowls. Didn't take the time to see if the fuel would stratify.
I'm certain that the bike will run fine now. My only concern is whether the tank vent is OK or not. Need to put some miles on it after topping off the tank.
Thanks to everyone for the suggestion
Click to expand...

Curious when you said cap not getting fuel on it....it will with each and every slosh about from below with more than say 1/2 a tank full. Carb spray squirt into the cap vent hole should clear it up....maybe follow with a wire poke or two for good measure.
 
Tornado said:
Curious when you said cap not getting fuel on it....it will with each and every slosh about from below with more than say 1/2 a tank full. Carb spray squirt into the cap vent hole should clear it up....maybe follow with a wire poke or two for good measure.
Click to expand...
If I squirt in carb cleaner, where will it come out?
 
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