1976 CB360T not allowing fuel into carbs?

Conis

New Member
Hello all,

Forgive me if this is posted in the wrong spot, I'm brand new at this. I have a 1976 CB360T cafe project that I recently finished up, and I have a carb issue that I just can't figure out. I'm running pods and shorter exhaust, and the carbs are pretty much stock other than 110 main jets. I know the general feeling here regarding that setup, but I'm really happy with how it turned out.


My issue is I have a vapor lock of some sort in the carburetors preventing fuel from filling the float bowls. It runs great for about 3 miles and then starts to bog as it runs it of fuel. I've determined the vapor lock is not due to the tank cap or petcock, as I have tested and rebuilt those numerous times thinking that was the problem. I've also pulled the carbs and attempted to clean out the vents to the float bowls with wire and carb cleaner. The vents appear to allow passage of air when the carbs are disassembled, but now that they're on the bike again the problem has returned.


Has anyone had this problem before or know what else I could try? Could this be related to the float height for some reason? Currently I've got them set at 18.5 mm per the manual. I'm not a master mechanic or anything, and I've hit the end of my knowledge. Thanks in advance for any help!
 

Conis

New Member
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irk miller

You've been mostly-dead all day.
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Vapor lock is vacuum in the tank.. Have you run it with the cap open just to be sure it's not actually vapor lock? The only other possibility would be the float needles sticking closed.
 

Conis

New Member
Vapor lock is vacuum in the tank.. Have you run it with the cap open just to be sure it's not actually vapor lock? The only other possibility would be the float needles sticking closed.
I have left it running with the cap open with no change. How could I test to see if the float stick? Last time I had it all apart it all seemed clean and functioning well.
 

teazer

Over 1,000 Posts
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Try running it up a quiet stretch of road and as it starts to bog/die, flip open the filler cap and see if it picks up. Or crack open the cap and take it for a gentle ride with the cap not sealed but not wide open and see if it keeps running.

Are you sure it's fuel and not something like say a condensor heating up and failing?

What do you do to get it to run again after it dies?
 

trek97

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My 360 did this years ago. It was heating fuel in the tank, boiling it in the hoses.
Start bike in garage and let her idle. Sit down and watch the fuel in the clear fuel lines you have on her.
After 5 or 10 minutes if you see bubbles begin to form inside the lines, preventing fuel flow...shes boiling.
Then shut her off a minute or two. They cool down and refill carbs. For another couple miles.
I installed adhesive heat shield to the bottom of tank, the thickest Heavy duty fuel line I could find, cut and fit as short as possible so it wasn't touching any thing metal, and fuel line heat shield wrap over the lines.
Fixed it.
This happened before I installed the high pipes. And even w high pipes running next to lines its still not an issue.

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trek97

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DTT BOTM WINNER
It’s possible you may not need the adhesive heat shielding under tank. Your stock tank sits a smidge higher on the frame than mine, allowing for better air flow.

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trek97

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DTT BOTM WINNER
Oh and because you didn’t ask my opinion I’m gonna give it to ya…
She will run and ride a whole hell of a lot better w proper air boxes, mufflers and fenders.
 

Conis

New Member
Try running it up a quiet stretch of road and as it starts to bog/die, flip open the filler cap and see if it picks up. Or crack open the cap and take it for a gentle ride with the cap not sealed but not wide open and see if it keeps running.

Are you sure it's fuel and not something like say a condensor heating up and failing?

What do you do to get it to run again after it dies?
Hey teazer,
So I tried opening the cap last night and it had no effect. I've gone through the electrical system and everything appears to be working as it should.

Normally to fix the problem I just get off of the throttle or let it idle until the fuel lines catch up a little.
 

Conis

New Member
My 360 did this years ago. It was heating fuel in the tank, boiling it in the hoses.
Start bike in garage and let her idle. Sit down and watch the fuel in the clear fuel lines you have on her.
After 5 or 10 minutes if you see bubbles begin to form inside the lines, preventing fuel flow...shes boiling.
Then shut her off a minute or two. They cool down and refill carbs. For another couple miles.
I installed adhesive heat shield to the bottom of tank, the thickest Heavy duty fuel line I could find, cut and fit as short as possible so it wasn't touching any thing metal, and fuel line heat shield wrap over the lines.
Fixed it.
This happened before I installed the high pipes. And even w high pipes running next to lines its still not an issue.

View attachment 232936
Trek97,
I've noticed the bubbles but never considered this! I did notice that the first few rides we're in cooler temperatures (gotta love buffalo NY lol), and it ran great. Recently it's been much warmer, and this is when the problem began.

I'll be trying this for sure and I'll keep ya posted! Thank you!
 

Conis

New Member
Yes report back.
Trek97,
So after heat shielding the fuel lines and tank I've seen a change. Fuel lines stay full, bowls stay full, bike rides great! I'm very thankful for the advice, I would have never figured that out.
 

trek97

No Custom Title
DTT BOTM WINNER
Trek97,
So after heat shielding the fuel lines and tank I've seen a change. Fuel lines stay full, bowls stay full, bike rides great! I'm very thankful for the advice, I would have never figured that out.
Super!!! Glad I could be of service buddy. Enjoy.
Now lets talk about fenders....hahaha
 

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