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Discussion Starter · #1 ·
hi everybody!


1974 360.
I’m trying to make this thing a daily driver.

Cam chain tension adjusted to spec
points gapped to spec
Valves adjusted to spec
New intake boots
Stock filters and boxes
Carbs clean as a whistle, rebuilt with fresh brass
Tank freshly lined, por15.
new plugs
New coils
New wires
New petcock
New(clear)fuel lin

new fuel cap

From cold, it starts runs and idles like a champ. Some spitting and popping revving to 9k but not much.

3 miles later, if I come to a stop it stalls and doesn’t want to start again. 20 minutes later it’s back to normal.

The clear lines let me see that they have trouble staying full, so it seems like a fuel delivery problem, but open the petcock with the lines off and it pours gasoline like a waterfall. It’s almost like there’s a vacuum created in the lines and I have to loosen them to bleed the air out of them, then they fill back up.

filling them up when it’s stalled does not allow it to restart, however.

Any tips? I’m tired of riding my aero 80 scooter, I look like a Mary.
 

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Your gas cap vent may be stopped up. Next time it happens, pop the cap open and see if it starts right up after a few seconds.
 

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Discussion Starter · #3 ·
Your gas cap vent may be stopped up. Next time it happens, pop the cap open and see if it starts right up after a few seconds.

Tried it, thanks. cap open or closed, no help.

maybe my floats are set too low and I'm stopping flow too soon. hm.
 

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When it stalls, have you checked to see if it still has spark at the plugs?
 

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Sounds like some sort of fuel delivery problem, then. Having the floats set too low would lean out the mixture, or it wouldn’t hardly run at all. Even if they were too low and that was causing the problem, the bowl would fill right back up when the motor stopped running. I‘d think it would more likely be something clogging or sticking the float valve almost closed. Coils overheating can also cause a problem like you describe. I know you said you have new coils, but did you ever leave the key turned on for a long period of time without the engine running? That will ruin a coil pretty quickly.
 

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Discussion Starter · #7 ·
Sounds like some sort of fuel delivery problem, then. Having the floats set too low would lean out the mixture, or it wouldn’t hardly run at all. Even if they were too low and that was causing the problem, the bowl would fill right back up when the motor stopped running. I‘d think it would more likely be something clogging or sticking the float valve almost closed. Coils overheating can also cause a problem like you describe. I know you said you have new coils, but did you ever leave the key turned on for a long period of time without the engine running? That will ruin a coil pretty quickly.
Hmmmm. Can you define a “long time”? I’ve had it on for a few minutes while setting points a couple times
 

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That won’t hurt it. I accidentally left one on for 15 or 20 minutes one time while working on it, and the coil got pretty hot, but still worked fine afterward. Usually, if one is heat damaged, you can tell by looking at it - the case may be swollen, or some of the insulation may be spewed out somewhere.
 

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Discussion Starter · #9 ·
That won’t hurt it. I accidentally left one on for 15 or 20 minutes one time while working on it, and the coil got pretty hot, but still worked fine afterward. Usually, if one is heat damaged, you can tell by looking at it - the case may be swollen, or some of the insulation may be spewed out somewhere.
Well then I’m off for another carb tear down.
Thanks, will update if I succeed.
 

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hi everybody!


1974 360.
I’m trying to make this thing a daily driver.

Cam chain tension adjusted to spec
points gapped to spec
Valves adjusted to spec
New intake boots
Stock filters and boxes
Carbs clean as a whistle, rebuilt with fresh brass
Tank freshly lined, por15.
new plugs
New coils
New wires
New petcock
New(clear)fuel lin

new fuel cap

From cold, it starts runs and idles like a champ. Some spitting and popping revving to 9k but not much.

3 miles later, if I come to a stop it stalls and doesn’t want to start again. 20 minutes later it’s back to normal.

The clear lines let me see that they have trouble staying full, so it seems like a fuel delivery problem, but open the petcock with the lines off and it pours gasoline like a waterfall. It’s almost like there’s a vacuum created in the lines and I have to loosen them to bleed the air out of them, then they fill back up.

filling them up when it’s stalled does not allow it to restart, however.

Any tips? I’m tired of riding my aero 80 scooter, I look like a Mary.

Look at the plugs and what they tell you!
hi everybody!


1974 360.
I’m trying to make this thing a daily driver.

Cam chain tension adjusted to spec
points gapped to spec
Valves adjusted to spec
New intake boots
Stock filters and boxes
Carbs clean as a whistle, rebuilt with fresh brass
Tank freshly lined, por15.
new plugs
New coils
New wires
New petcock
New(clear)fuel lin

new fuel cap

From cold, it starts runs and idles like a champ. Some spitting and popping revving to 9k but not much.

3 miles later, if I come to a stop it stalls and doesn’t want to start again. 20 minutes later it’s back to normal.

The clear lines let me see that they have trouble staying full, so it seems like a fuel delivery problem, but open the petcock with the lines off and it pours gasoline like a waterfall. It’s almost like there’s a vacuum created in the lines and I have to loosen them to bleed the air out of them, then they fill back up.

filling them up when it’s stalled does not allow it to restart, however.

Any tips? I’m tired of riding my aero 80 scooter, I look like a Mary.
Check petcock screen filter!
 

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I had a similiar problem with mine and it was the coils. Would run great when cold but after a few miles would quit. I rebuilt the carbs 5 times chasing my problem. It was the coils. Run it until it quits and see if it has spark.
 

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Discussion Starter · #13 ·
I had a similiar problem with mine and it was the coils. Would run great when cold but after a few miles would quit. I rebuilt the carbs 5 times chasing my problem. It was the coils. Run it until it quits and see if it has spark.
I must have messed something up with the floats. I had five minutes to spare while helping a friend with his mower and I opened the bowl drain screw. I got a trickle then it stopped. Even with the petcock on. And the file lines were full and didn’t drain.
I’ll get back at it today.
 

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73 CL450, 74 CL360
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I have exactly the same problem with mine. I have done everything mentioned on this string and more. I found mine was running way too rich, which makes it run while cold and not when warmed up. Haven’t had tome to fix it because I’ve been in a family vacation but will get back to it soon. Try pulling off the air filters and see if it keeps running when hot. If it does then you need to jet your carb or find the air restriction. Which is what I am about to do when I get back home off vacation!
 

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Discussion Starter · #15 ·
I had a similiar problem with mine and it was the coils. Would run great when cold but after a few miles would quit. I rebuilt the carbs 5 times chasing my problem. It was the coils. Run it until it quits and see if it has spark.
It seems crazy to me, but the float needles are sticking. I took everything back apart and the needles were stuck fast in their housing.

pulled them out, cleaned, lightly oiled, reassembled.

now one sticks open and the other one sticks closed.

I don’t understand it. Unless they’re sized wrong? Or corrode extremely quickly? They’re from a common motor rebuild kit for 360s.
I guess on the next rebuild I’ll try the stock needles and see if they do better. It’s really annoying.
 

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It seems crazy to me, but the float needles are sticking. I took everything back apart and the needles were stuck fast in their housing.

pulled them out, cleaned, lightly oiled, reassembled.

now one sticks open and the other one sticks closed.

I don’t understand it. Unless they’re sized wrong? Or corrode extremely quickly? They’re from a common motor rebuild kit for 360s.
I guess on the next rebuild I’ll try the stock needles and see if they do better. It’s really annoying.
If the original brass parts can be cleaned and reused, always do that. You never know what you’re getting in those “kits”, and there are often badly manufactured and/or incorrectly sized parts in them.
 

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Discussion Starter · #17 ·
If the original brass parts can be cleaned and reused, always do that. You never know what you’re getting in those “kits”, and there are often badly manufactured and/or incorrectly sized parts in them.
Cleaned again, and this time I made sure to lube and open/close the float valve a few hundred times to break it in.
You’re almost certainly right about less than perfect manufacturing.

I still have my original brass if this doesn’t work out.
 

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Discussion Starter · #18 ·
No news, float problem seems solved, but still sputters terribly when sitting at steady rpm, and stalls.

i know its getting gas, but i feel like its getting it inconsistently? and sometimes too much. the stall feels more like a flood than a lean.
 

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Put a straight edge across the mating faces of your manifold, carby to cylinder. I found small "warping" on the rubbers and after rebuilding the carbs many times to address the kind of issues many people are having this was a fix that had a hugely beneficial effect at all revs. Replaced them with brand new ones from WEMOTO in Australia. Should have picked it up earlier. Especially the right side carb. good luck.
 
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