TM38-27, 38mm TMX Mikuni 2 Stroke Racing Carb (44mm or 47mm Spigot)

The TM38-18 is supplied with the following factory jetting installed:

Pilot jet 20 (VM22/210),  Needle 6EJ12-55 (richer and leaner available),  Needle Jet (Fixed in place),  Main Jet 370 (4/042),  Slide  3.5 (999-832-014)

Unlike many motorcycle manufacturers’ purpose built and modified pollution compliant versions of the TMX carb, these factory TMX flatslide racing carbs are regarded by the factory to be the best performing version of this carburetor ever made.

The TMX features a flat slide design in a smooth bore venturi to provide improved throttle response and wider powerband. The float system with independently moving floats, working with a main jet enclosed in a baffle chamber, allows the TMX to perform smoothly without hesitation on the roughest terrain. These carbs are jetted to suit virtually anything from later model 125cc high performance motocross engines, all 250cc reed valve motors and also all of the larger two stroke engines which perform great with often never a jet change. If fitting to a piston port engine, they do require a drastic jetting down size.  Once fitted it will eliminate a lot of the hesitation, hard starting and other performance problems experienced with some OEM carbs and best of all will boost performance..

It is always advised to buy a spare one size up (380) and one size down (360) main jet so as to positively verify your correct fuel mixture and optimum power at WOT. When replacing carbs with throttle position sensors and other such electrical items fitted you will need to determine if these do not need to be connected before purchasing and installing one of our carbs.

If your carb measures around 12mm, 20mm or 40mm longer than the 76mm front to back measurement of the TMX carb, and if intending to still use the standard air-box you will need to purchase separately from our TMX Carbs page the corresponding silver anodized extender. When ordering an extender with your carb please advise in the order comments section if you want us to press fit it to your carb with Loctite before delivery. The two shorter extenders have an outside diameter of 60mm at the air-box end which is slightly smaller than the carb itself and the 40mm long one is 62mm diameter.

The picture above with the cable shows the required length of inner cable protrusion and securing fitting required at the carb end at basically a minimum length adjustment. The back board is divided into 1 and 10mm increments. If your inner cable is to short you may consider one of our Quick Action throttle and cable assemblies.