Suzuki DRZ400 | Mikuni TM40-6 Flatslide Pumper Carb Kit | DRZ 400

The Suzuki DRZ400 Mikuni TM40-6 Flatslide Pumper Carb Kit is a high-performance upgrade designed to transform your bike's throttle response and overall rideability. Say goodbye to frustrating hard starts, hesitation, bogging, and flat spots—the TM40-6 flatslide carb with built-in accelerator pump (pumper) delivers crisp, instant power delivery and smoother performance across the rev range.

Suzuki originally equipped the DRZ400 with one of two factory carbs: a CV-style Mikuni (common on street/dual-sport models) or a flatslide Keihin (typically on off-road variants). Both can suffer from issues like throttle valve wear over time, leading many owners to upgrade.

This kit features a genuine Mikuni TM40-6 carburetor, known for its smoothbore design, superior airflow, and accelerator pump that eliminates lean spots during sudden throttle openings—perfect for trail riding, supermoto, or any spirited use.

Kit Options and What's Included

Select your carb option based on your current setup:

• Replacing a Keihin carb (common on off-road models): Includes the TM40 carb body, a pre-fitted 47mm OD outlet sleeve (to match the Keihin's motor-side diameter), quick-action throttle, nylon-lined throttle cables, knob-style choke (or optional cable choke with universal mounting bracket on request), pre-installed jets, and spare jets for tuning.
• Replacing a Mikuni BST CV carb (common on street/S models): Includes the TM40 carb, optional quick-action throttle and nylon-lined cables (your stock throttle and cables can often be adapted), knob choke (or optional cable choke/bracket), pre-installed jets, and spares.

The TM40-6 is approximately 100mm front-to-back and uses a side-pull knob choke as standard.

Installation Notes

Fitting is straightforward for most, though some modifications may be needed depending on your bike's exact setup:

• You may need to loosen or remove the rear frame section to access and remove the airbox compartment.
• For shorter Keihin carbs (e.g., 95mm or 88mm versions), options include grinding an internal ridge in the engine-side rubber mount to allow deeper insertion (clearing the tank/frame) or other minor adjustments—no cutting required on the carb itself in some cases.
• For CV Mikuni replacements, confirm your measurements (typically ~42mm OD motor end, 95mm length, 58mm airbox end). The inlet can often be clamped snugly without an extra sleeve.
• Check the included photo library or step-by-step guides (similar processes apply across models) for visuals on UK/Euro SM installs or similar.

Once installed, fine-tune using the provided jets and spares—adjustments account for variables like climate, altitude, fuel type, aftermarket cams, exhaust, porting, or big-bore kits. Many users report excellent out-of-the-box performance with minimal dialing in.

Check photos for help on how to install the carb kit or contact us