Fuel and Intake

The OEM vent foam filter can deteriorate after only a couple of years. When it does it can allow enough dirt into the engine to do significant damage. Replace your filter now with a washable cotton & steel screen filter.

This filter is recommended to be oiled like any other air filter to work properly.

Only for bikes with the stock BST40 carburetor!

The OEM foam secondary filter can deteriorate rather quickly. Once that happens, it can allow enough dirt into the engine to do significant damage. Replace your filter now with a high-quality foam filter from industry leader Twin Air.

This filter needs to be oiled like any air filter to work properly.

Only for bikes with the stock BST40 carburetor!

This is an O.E. replacement diaphragm for your BST40 carburetor.

Replacement socket head (Allen) screws for the OEM BST40 Carburetor. The factory screws that hold the top cap and float bowl on the stock carburetor are very easily damaged. The originals are usually installed unbelievably tight from the factory. It is common to ruin the stock screws when installing a jet kit or doing any other carburetor maintenance. Sold in a pack of four. Two for the cap and two for the float bowl.

This Kit replaces vital components in the BST40 Carburetor including new a Float, Needle Valve, Gaskets, Seals, Diaphragm, Spring and Float Bowl Screws to return the stock Mikuni BST40 Carburetor to like-new operation. As a bonus we have included Viton o-rings for the float assembly and 4 stainless steel allen screws.

A new slide for the stock Mikuni BST carburetor.

Replace the worn slide guide in your stock Mikuni BST carburetor before it causes additional wear to the needle and needle jet. There are wear indicators on the slide guide that help you recognize when it is time to replace your slide guide.

The plastic fitting that secures the stock choke cable to the carburetor is delicate and easily broken. A broken fitting can cause hard to solve idling and running problems.

CNC machined from billet aluminum and anodized black or blue. If you want to retain your handlebar mounted choke this may be the solution.

  These no longer fit the new version of the ProCycle Remote Choke Cable. Will not work with the long or short reach choke knobs.

Replace your handlebar mounted choke with this simple knob mounted directly on the carburetor.

Available in short or long reach.

Long reach is easier to use while wearing riding gloves.

Works for either the stock BST or Mikuni TM40.

This brass fuel screw offers a longer head to give you a better hold for making adjustments. This is a nice improvement over the standard extended fuel screw. Kit includes one new screw, spring, washer and o-ring.

Designed for use with stock engines using either stock or aftermarket exhaust and air filters.

• Provides a simple and affordable solution to carburetor tuning problems.
• Allows you to tune your bike for increased power and smoothness while retaining fuel economy.
• Includes a guide booklet on how to install and use your jet kit to it's full potential.
• For a top quality installation we recommend adding an extended fuel screw and a set of replacement carburetor screws.

Kit includes:

• 155 Main Jet
• 40 pilot jet
• #35 leak jet
• EMP needle

Not for the stock carburetor Fits FCR-MX conversions Only.

Kit includes:

• Main jets: 145, 150, 155 and 160
• Pilot jets: 38, 40 and 42
• Merge Racing AP spring
• JD Fuel screw
• #35 leak jet
• EMP and EMR needles

Everything you need to dial in your FCR/DR650 conversion. Enough jetting to cover most modifications or altitudes.

Not for the stock carburetor Fits FCR-MX conversions Only

Replacement rubber boot for choke knob assembly.