Low Rider build... mounting issues

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P

Pcain

New Member
Apr 30, 2012
33
0
0
Melb Australia
Hey guys,

I got my 66cc engine kit recently and i've been playing around with how i'm going to make it fit on my bike frame. (see thread from a couple weeks back for bike pics).

My concern is that i've had to chop the intake manifold to fit the carb in the frame. As the manifold bends, how crucial is it to be "level"? My carb air filter is facing my seat basically. It is at possibly a 40 degree'ish angle.

I was assuming that as the fuel would most likely be suction feed this shouldn't be a problem, however I don't know much if anything about these carbs.

Also, the exhaust side mount is a bit narrow for that part of my frame. Because space is minimal, a mounting plate won't do. Is there a way to bend that small section of my frame, to crimp in a way, so that it is narrower? I don't care much for the aesthetics as I will be painting it etc.

Any help re these issues would be greatly appreciated!

Cheers

Chris
 
dragray

dragray

New Member
Mar 10, 2012
278
2
0
Indiana
if the carb is at a 40% angle (based on the way you are describing it) with the rear of the carb higher than the front, it will flood over.
the carb does need to be as level as possible because the fuel in the float bowl needs to be level.

if it's at an angle, the fuel can overflow up into the carb through the main jet and the carb will flood. just like tilting a glass full of water. you can tilt it a little, but eventually the water will start to spill over the edge.

the other thing that can happen with the carb at an angle is that the float bowl can "run out" of gas as you're riding at w.o.t.

what i mean is that since the main jet is in the center of the float bowl, hanging down into the fuel that's in the bowl. if the fuel is at an angle, eventually the fuel level will drop below the main jet where the fuel is low due to the angle.
there will still be fuel left in the bowl to keep the float high enough for the needle & seat to stay closed, which will not allow more gas to flow into the bowl to bring the level up to the main jet.

take a straw, and put it in a glass 1/2 full of water, but have the straw about 1/2 inch into the water (not all the way to the bottom of the glass.). put tape across the top of the glass to hold the straw so it can't move up or down.
now, suck on the straw and tilt the glass at the same time without lowering the straw. eventually, the straw will be out of the water, but there will still be a lot of water in the glass.
this is the same principle as having the carb at an angle.
 
Last edited:
P

Pcain

New Member
Apr 30, 2012
33
0
0
Melb Australia
dragray said:
if the carb is at a 40% angle (based on the way you are describing it) with the rear of the carb higher than the front, it will flood over.
the carb does need to be as level as possible because the fuel in the float bowl needs to be level.

if it's at an angle, the fuel can overflow up into the carb through the main jet and the carb will flood. just like tilting a glass full of water. you can tilt it a little, but eventually the water will start to spill over the edge.

the other thing that can happen with the carb at an angle is that the float bowl can "run out" of gas as you're riding at w.o.t.

what i mean is that since the main jet is in the center of the float bowl, hanging down into the fuel that's in the bowl. if the fuel is at an angle, eventually the fuel level will drop below the main jet where the fuel is low due to the angle.
there will still be fuel left in the bowl to keep the float high enough for the needle & seat to stay closed, which will not allow more gas to flow into the bowl to bring the level up to the main jet.

take a straw, and put it in a glass 1/2 full of water, but have the straw about 1/2 inch into the water (not all the way to the bottom of the glass.). put tape across the top of the glass to hold the straw so it can't move up or down.
now, suck on the straw and tilt the glass at the same time without lowering the straw. eventually, the straw will be out of the water, but there will still be a lot of water in the glass.
this is the same principle as having the carb at an angle.
Click to expand...

Thanks for that. I'm thinking i'll be making a very low profile manifold to fit.

Any thoughts on crimping that frame?
 
B

BikeBerry.com

Dealer
Nov 7, 2008
38
0
6
California
www.bikeberry.com
dragray said:
if the carb is at a 40% angle (based on the way you are describing it) with the rear of the carb higher than the front, it will flood over.
the carb does need to be as level as possible because the fuel in the float bowl needs to be level.

if it's at an angle, the fuel can overflow up into the carb through the main jet and the carb will flood. just like tilting a glass full of water. you can tilt it a little, but eventually the water will start to spill over the edge.

the other thing that can happen with the carb at an angle is that the float bowl can "run out" of gas as you're riding at w.o.t.

what i mean is that since the main jet is in the center of the float bowl, hanging down into the fuel that's in the bowl. if the fuel is at an angle, eventually the fuel level will drop below the main jet where the fuel is low due to the angle.
there will still be fuel left in the bowl to keep the float high enough for the needle & seat to stay closed, which will not allow more gas to flow into the bowl to bring the level up to the main jet.

take a straw, and put it in a glass 1/2 full of water, but have the straw about 1/2 inch into the water (not all the way to the bottom of the glass.). put tape across the top of the glass to hold the straw so it can't move up or down.
now, suck on the straw and tilt the glass at the same time without lowering the straw. eventually, the straw will be out of the water, but there will still be a lot of water in the glass.
this is the same principle as having the carb at an angle.
Click to expand...
This is awesome advice! Thank you for explaining it with an example of something else, it clears up the situation it way that is common enough for anyone to relate to.
 
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