Gas Tank V?s Auxiliary Fuel Tank to tune Carbs

[RobG1970]

Guys,
Whats your feelings on using a Auxilary Fuel Tank v?s the Gas Tank to fine tune your bike>? I sometimes feel that me Auxilary tank is starving the carbs for enough fuel.. any thoughts>???

​

 

[GateKeeper]

just did a carb tune on my bike, using an IV bottle method, had no issues, actually didn't even use up all the gas we poured in....

 

[Steve]

I sometimes feel that me Auxilary tank is starving the carbs for enough fuel.. any thoughts>???​

The only way that your tank is going to starve the carbs is if it runs dry.

The tubing between your tank and the carbs might be another matter. However, since virtually all the the "fine tuning"
that you will do with the tank off the bike is at or near idle speed, it doesn't really take much in the way of tubing
to provide enough gas to the carbs.

Just as important, is that you need to have your gas level in your aux tank at about the same height as the stock tank.

.

 

[RobG1970]

The only way that your tank is going to starve the carbs is if it runs dry.

The tubing between your tank and the carbs might be another matter. However, since virtually all the the "fine tuning"
that you will do with the tank off the bike is at or near idle speed, it doesn't really take much in the way of tubing
to provide enough gas to the carbs.

Just as important, is that you need to have your gas level in your aux tank at about the same height as the stock tank.

.

Thanks Steve - I have actually NEVER ran the tank on the bike yet, when I saved her, she wasn?t running and the tank was filled with crap, so I got a auxiliary tank and its suspended right above the bike from the ceiling. (will post pic later) I just feel like for some reason the bike is staving for fuel, all the floats are matched, the bike is completely stock, carbs rebuilt and cleaned, and clean and cleaned, new boots all around, no air leaks. When I crack the throttle, its just seams like it takes to long for the fuel to recover.​

 

[MisterCinders]

I have tried to rig up auxiliary tanks, but finding a good way to connect the fuel tube to a bottle always goes sideways for me.

So I just set the tank on a stack of milk crates to keep it at the appropriate height, and then run a longer fuel line to feed the carbs for synching, tuning, etc. Also, I like to use a low-flow inline filter as a "quick connect" for the longer line. That way the line from the carb T to the tank stays connected to the T. I can plug in the filter to connect another length of line to remote tank, and when everything checks out, I disconnect the filter and extra line and reconnect the tank to the line running off the carb T.

ASCII diagram:

[Carb T] - - - [Filter] - - - - - [Tank]

for testing becomes

[Carb T] - - - [Tank]

for operation.

HTH

 

[RobG1970]

I have tried to rig up auxiliary tanks, but finding a good way to connect the fuel tube to a bottle always goes sideways for me.

So I just set the tank on a stack of milk crates to keep it at the appropriate height, and then run a longer fuel line to feed the carbs for synching, tuning, etc. Also, I like to use a low-flow inline filter as a "quick connect" for the longer line. That way the line from the carb T to the tank stays connected to the T. I can plug in the filter to connect another length of line to remote tank, and when everything checks out, I disconnect the filter and extra line and reconnect the tank to the line running off the carb T.

ASCII diagram:

[Carb T] - - - [Filter] - - - - - [Tank]

for testing becomes

[Carb T] - - - [Tank]

for operation.

HTH

OKOK... Cool... Thanks..

 

[Seana23]

I have tried to rig up auxiliary tanks, but finding a good way to connect the fuel tube to a bottle always goes sideways...


HTH

Try the wee bottle you get with battery acid. .. Just snip the nozzle end off and slide it into the fuel pipe...

And a small bolt i the vacume pipe ...
It works brilliently.

Xxx

 

[MisterCinders]

Try the wee bottle you get with battery acid. .. Just snip the nozzle end off and slide it into the fuel pipe...

And a small bolt i the vacume pipe ...
It works brilliently.

Xxx

I might do that. I see loads of pics where people use gear oil bottles and other containers with a tapered end/spout. Without a need for gear oil or the the other liquids I see offered in that style of bottle, I never got hold of one. Not going to spend $15 on gear oil just to salvage the bottle.

To my own shame, I have been coveting a toilet bowl cleanser bottle in the house because it looks like the right shape of top. "Man these toilets are filthy!" - but repeated cleanings haven't emptied that bottle yet.

 

[Dreef1999]

Thanks Steve - I have actually NEVER ran the tank on the bike yet, when I saved her, she wasn?t running and the tank was filled with crap, so I got a auxiliary tank and its suspended right above the bike from the ceiling. (will post pic later) I just feel like for some reason the bike is staving for fuel, all the floats are matched, the bike is completely stock, carbs rebuilt and cleaned, and clean and cleaned, new boots all around, no air leaks. When I crack the throttle, its just seams like it takes to long for the fuel to recover.​

your problem doesn't sound like it is caused by fuel flow. It sounds like your carbs are not tuned.

I hazard a guess that a hesitant throttle is a rich condition? Too much fuel.

 

[RobG1970]

your problem doesn't sound like it is caused by fuel flow. It sounds like your carbs are not tuned.

I hazard a guess that a hesitant throttle is a rich condition? Too much fuel.

OKOK.... I JUST re-lashed the valves (again.. long story), so I am waiting to do a GOOD sync on the carbs.. I am hoping that it shooths things out...

 

[Seana23]

I may be being a bit blonde but.....

What is re lashing the valves?

Excuse my ignorance.
X

 

[Guest]

The only way that your tank is going to starve the carbs is if it runs dry.

The tubing between your tank and the carbs might be another matter. However, since virtually all the the "fine tuning"
that you will do with the tank off the bike is at or near idle speed, it doesn't really take much in the way of tubing
to provide enough gas to the carbs.

Just as important, is that you need to have your gas level in your aux tank at about the same height as the stock tank.

.

Steve, what's the importance of the same height? isn't the amount of fuel regulated by the floats making the height irrelevant? just wanting to make sure I'm not doing another crazy mistake.

 

[GateKeeper]

Until Steve answers, I will through in my thought, if I remember from my days in high school....

if it's higher it will have greater pressure pushing it through the feed tube, could cause an overflow situation

I think

but I have been known to be wrong

 

[BassCliff]

Hi,

Since it is a gravity-fed system, if your tank is below the carbs then fuel will not flow into the carbs. (Liquids do not flow up hill.)

Thank you! Thank you! This is Captain Obvious signing off!


Thank you for your indulgence,

BassCliff

 

[GateKeeper]

Well that would go without saying....

Captain Obvious....LOL

same or above, but would it matter if it was really high ? I was just thinking it would/could cause excess pressure, no ?

me not so Captain Obvious....LOL

 

[BassCliff]

Hi,

same or above, but would it matter if it was really high ? I was just thinking it would/could cause excess pressure, no ?

If it was a large amount of fuel some 20 or 30 feet in the air then it might make a difference. But my IV bottle system is usually about a foot or so higher than where the fuel tank would be and I have no problem with carb sync'ing.

Thank you for your indulgence,

BassCliff

 

[RobG1970]

LOL Its actually about 15 feet in the air... I took pics tonight but didnt have the time to download the yet ..lol

Hi,



If it was a large amount of fuel some 20 or 30 feet in the air then it might make a difference. But my IV bottle system is usually about a foot or so higher than where the fuel tank would be and I have no problem with carb sync'ing.




Thank you for your indulgence,

BassCliff

 

[RobG1970]

I may be being a bit blonde but.....

And there are no stupid questions, only stupid answers...

What is re lashing the valves? Setting the valve clearance

Excuse my ignorance.
X

Valve lash is setting the valves

 

[Steve]

Steve, what's the importance of the same height? isn't the amount of fuel regulated by the floats making the height irrelevant? just wanting to make sure I'm not doing another crazy mistake.

Until Steve answers, I will through in my thought, if I remember from my days in high school....

if it's higher it will have greater pressure pushing it through the feed tube, could cause an overflow situation

I think

but I have been known to be wrong

You are quite right, Mr. GateKeeper. :clap: :clap:

Yes, the floats are designed to stop fuel flow, but stop and think for a moment what would happen if you raised the fuel pressure that the floats are trying to hold back. :-k

Not sure how much of a difference it will make by being a few inches off, but why push your luck? I try to tune by simulating conditions as close as possible to the way they will be while running.

LOL Its actually about 15 feet in the air... I took pics tonight but didnt have the time to download the yet ..lol

OK, pictures will help, but how, or more importantly, WHY so high?

I just can't imagine climbing something that high to pour a bit of gasoline in, when it is so EASY to make something that will hang on the handlebars or sit on the frame rail over the airbox/battery area.

Personally, I use a gallon-size oil jug that has a hole drilled in the cap. Because of the possibility of leaking where the hose goes through, I CAN NOT RECOMMEND THIS METHOD, but it works for me. Also, by keeping the jug no more than half full, I can rotate it to turn the gas flow ON or OFF.

Here is the jug:

Here, it is turned OFF:

Here, it is turned ON:

OK, you don't have to be real sharp to notice that there is also a gas tank in the picture.
These pictures were not taken during a tuning session, they were taken during a previous discussion about a temporary tank, so I just removed the seat and set the temp tank on the frame.

.

 

[tas850g]

Steve, do you have pics on how you seal the hole with the hose so it does not leak?