Fuel line routing question

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hjans
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Fuel line routing question

#1

Post by hjans »

Hi there
Started up my project after 4 years built.
She runs very smooth now.
Only problem : airlock in fuel line.( hope that's all, manifold seemes to be airtight)
Gas is boiling in line , bubbles in tank, resulting in problems starting when hot.
I already have new copper to make/bend a new gasline. ( yes i now original is steel)
Can anyone tell/show me the original/optimal/practical/good way to route it ?
I have the trumpet style horn on my "59 Pab, that might make things a bit more difficult.

Thanx

Hans
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Re: Fuel line routing question

#2

Post by Bosheff »

I don't know how ya routed yer fuel line, but I'm guessin that it runs between cylinders at some point, right? If that is the case and ya got a vapor lock condition, try covering the existing steel/copper/whatever fuel line with rubber fuel line for insulation especially where it is routed between the jugs....bosheff
awander
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Re: Fuel line routing question

#3

Post by awander »

Copper WILL work-harden and eventually break from the vibration on your Pan. Use steel.
JohnnysCustomPaint
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Re: Fuel line routing question

#4

Post by JohnnysCustomPaint »

awander wrote:Copper WILL work-harden and eventually break from the vibration on your Pan. Use steel.

And more than likely catch you and your scoot on fire.
Can the copper!
Kuda
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Re: Fuel line routing question

#5

Post by Kuda »

hjans wrote:Gas is boiling in line , bubbles in tank, resulting in problems starting when hot.
Wow, that's HOT!! I've ridden with the stock steel lines routed less than 1/4" from the cylinders and never come close to that kinda heat. In fact, even after idling in traffic for extended periods I can still reach down and touch the gas line and it won't burn my hand at all (the cylinder would cook me in a second, but not the gas line). The stock line should cross between the cylinders as LOW as possible, where it's coolest. Also, make sure you're using an insulator between the manifold and the carb (I always run one, even tho' I've never really seen a need, but this might be one). If this doesn't work, you can also make your own steel line that's longer, to give you more room to route it away from the cylinders.

One thing tho', just on the off chance you're reading the symptoms wrong: make sure the gas caps are vented correctly. I've seen a hot motor heat the gas in an incorrectly vented tank to the point it pushed gas past the float into the manifold.

-Kuda
'49 panchop
hjans
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Re: Fuel line routing question

#6

Post by hjans »

Kuda wrote:
hjans wrote:Gas is boiling in line , bubbles in tank, resulting in problems starting when hot.
Wow, that's HOT!! I've ridden with the stock steel lines routed less than 1/4" from the cylinders and never come close to that kinda heat. In fact, even after idling in traffic for extended periods I can still reach down and touch the gas line and it won't burn my hand at all (the cylinder would cook me in a second, but not the gas line). The stock line should cross between the cylinders as LOW as possible, where it's coolest. Also, make sure you're using an insulator between the manifold and the carb (I always run one, even tho' I've never really seen a need, but this might be one). If this doesn't work, you can also make your own steel line that's longer, to give you more room to route it away from the cylinders.

One thing tho', just on the off chance you're reading the symptoms wrong: make sure the gas caps are vented correctly. I've seen a hot motor heat the gas in an incorrectly vented tank to the point it pushed gas past the float into the manifold.

-Kuda
'49 panchop
Gascaps where off the tanks ( both of them), problem occured during finetuning carb, wich took a long time. I recognized the problem during idling at trafic lights ( wich there are a lot of them around here).
Gasline is not original and probably too short, thus almost touching the front cyl.
Rerouted it now as low as possible, right above the horn-tube.
It also first was routed behind (??) the sparkplug, now it comes off the pan first, to then go past the horn.
Think the problem is past now, otherwise isolate the lot.

Copper line isn't bad at all, as long as you use a piece of rubber fuel line around it for 1 or 2 inches. It acts as a vibration absorber.

Hans
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