DIY Curved Manifold
For some applications, our upgraded carburetor/manifold
combination cannot be installed due to clearance issues.
On race karts the carb or air filter may hit the right rear
tire. On barstool racers the carb may hit the foot rest
on the barstool. We offer this solution for the do-it-yourselfer.
You will need:
- One of our manifolds. You may choose a manifold with or without a pulse fitting.
- A radiator hose which contains the desired angle. For our race kart we went with a 45 degree bend. The radiator hose needs a 1 1/4" ID.
- Two hose clamps.
Cut the manifold in half. A band saw or hack saw works great for this. Cut out the section of radiator hose you plan to use.
- First bolt on the head side of the manifold.
- Slide the hose onto the head flange and clamp in place.
- Slide the carburetor side of the manifold into the hose and clamp securely.
We install a support brace from one of the carburetor bolts, down to a shroud bolt to reduce vibration.
Complete setup installed.
AGK customer Tim Armstrong built an excellent version of the DIY curved manifold. The following information was provided by Tim.
Used 1/8" x 1/2" flat steel for support bracket.
One bracket is secured at the carb bolt on one end and at a fan shroud
bolt at the other end.
The second bracket secures the first bracket to the cylinder head for extra rigidity.
Allen bolts were used to secure the flanges to the cylinder head and carburetor. Notice there is plenty of clearance between the carb and right rear tire.
Keeping the curved hose as short as possible helps prevent vibration and keeps the hose from collapsing due to vacuum from the piston.
The completed curved manifold has the carburetor pointing straight back behind the engine.
Started 1st pull ran and idled very nice.
Left 22 mm Mikuni stock for a few laps to see what it felt like. Plug
showed it was lean, almost white. Placed the needle jet in the
middle slot and went to a 120 main jet. This adjustment made the kart
come to life. Checked plug after running and still a little lean so went
to a 125 main and that is where it is now and runs great. Air mixture at
2 turns out. I am very happy with the performance, thank you Tim
Making a DIY curved manifold and turning the carburetor
forward instead of back has proven to be a good idea. The longer
piece of radiator hose requires a flexible coil spring on the inside so
it does not collapse. These long manifolds make great power and
they get cold with condensation dripping from them like a tunnel ram.
With the air filter pointing forward there is also a ram air effect.
This carb has a short brace that comes off of the fan shroud and goes to
the carb flange. A good brace is important and the coil spring
inside the radiator hose is important (especially when the manifold is
Tim tells us the forward facing carburetor is much
improved over the traditional rear facing carburetor. The lower
air/fuel temperatures from the long manifold and ram air effect into the
carburetor make a great combination for power.