Intake Manifolds | Honda SL350 (K1-K2)

Intake Manifolds | Honda SL350 (K1-K2)

Replacement intake manifolds for Honda SL350 (K1-K2) motorcycles. Sold in pairs.

Why You Need This

The Honda SL350 K1 & K2 motorcycles introduced a lot of changes to the parts used on them compared to earlier SL350 K0 and CB350 / CL350 models. One of the more significant updates was the change to a unique set of slide carburetors along with a redesigned cylinder head featuring smaller intake ports. Because of these unique carburetors and recast head, the SL350 K1-K2 models required a one-off set of intake manifolds, not used on any other models in the Honda lineup. Unfortunately, original manifolds have long since dried up and hardened, leaving owners with virtually zero reliable replacement manifolds that would work well on these models.

Our replacement manifolds are one of the few aftermarket options that fit and work well on these motorcycles. While they are not factory originals, with a slight modification they look great and perform properly on the Honda SL350 K1-K2 models. Additionally, they include a built-in vacuum port on each manifold, allowing you to easily vacuum sync the carburetors.

Specifications

Note: These intake manifolds do not come ready to install and require light filing on the mounting holes to properly fit your SL350 K1-K2. See the installation instructions below for the full modification procedure.

Model-Specific Notes

• SL350 K0: These intake manifolds do NOT fit these models. Find intake manifolds for the CB350 / CL350 / SL350 K0 right here.

What's in the Kit

• Intake manifold x2
• Intake manifold gasket x2
• Intake manifold vacuum port cap x2
• Intake manifold clamp x2

Installation

Difficulty: Beginner

Tools needed: Round file

1. These intake manifolds require light filing on the mounting holes in order to properly bolt onto Honda SL350 K1-K2 cylinder heads.
2. Using a round file, elongate each mounting hole outward — away from the center of the manifold — to widen the spacing between the two holes. Remove approximately 1.5 mm from the outer edge of each hole, which typically takes about 2 to 3 minutes per hole.
3. After filing both sides, hold the intake manifold up to the cylinder head and confirm that the cylinder head studs sit fully within the newly enlarged holes. See the listing photos for a reference of what modified holes look like.
4. Before installing the new manifold, make sure all old gasket material has been removed from the cylinder head port surface. The mounting surface should be completely clean and smooth.
5. Install the gasket against the cylinder head, then mount the intake manifold to prevent vacuum leaks. We also recommend applying a small amount of anti-seize to the intake manifold bolt threads before installation.
6. Once the intake manifolds are installed, press the included vacuum port covers onto the vacuum ports on the new intake manifolds to complete the installation. For added security, you may use a small zip tie around each vacuum port cover, although this is not required.

These replacement manifolds include vacuum ports that can be used to vacuum sync Honda SL350 K1-K2 carburetors. If you choose to use them for carb synchronization, be sure to reinstall the vacuum port covers immediately afterward. Operating the motorcycle without the vacuum port covers installed will create a major vacuum leak, causing the engine to run extremely lean and potentially resulting in engine damage.

Frequently Asked Questions

Does this fit both the Honda SL350 K1 and SL350 K2?

Yes. These replacement intake manifolds are designed for the Honda SL350 K1 and SL350 K2. Because of their universal design, a small amount of filing is required on the mounting holes to achieve proper fitment on the cylinder heads.

Are these OEM style intake manifolds?

Yes and no. Usable OEM intake manifolds are extremely difficult to find. Our replacements use a universal design and require a small amount of filing on the mounting holes before installation. They also include integrated vacuum ports, which can be used to vacuum sync the stock slide carburetors. Once modified, they are an excellent solution for keeping the rare Honda SL350 K1-K2 on the road.

What are the vacuum ports for?

The built-in vacuum ports allow you to vacuum sync the carburetors if desired. Traditional synchronization methods can still be used, but these ports provide an added tuning option. The vacuum port covers must remain installed anytime the motorcycle is running under normal operation. Running the engine without the covers in place will create a major vacuum leak, which can cause a lean condition and may lead to engine damage.

Last updated: May 2026