Mikuni Smoothbore Carburetor

Racing Air Intake Performance TM33-8012

Posted by Brad

Mikuni Smoothbore Carburetor TM33-8012 When Mikunis showed up on the scene, racers quickly adopted them. This was back when your choices were such as Linkert, Amal, Dell'Orto, SU, and a few others -- all of which were well known for their limitations at the time. Mikuni provided a carburetor that increased performance, was easily adjusted to modifications made to an engine, and proved to be reliable. To this day, some of their older designs are still in use and prized by both collectors and vintage bike restorers.

Now, most carburetor companies sell a reasonably good product. Mikuni remains right up there with the best, however, and they have a variety of choices for just about every make and model in production.

The TM33-8012 is a smoothbore carburetor, which simply means the bore (or main air intake) is smooth to prevent air turbulence that might restrict air flow. It's also a pumper, meaning it has a push-pull throttle assembly that pumps fuel into the carb via a mechanical diaphragm; the extra boost of fuel helps prevent the engine from leaning out, especially under acceleration. As well, it was designed with a "square" or "flat" type of slide, said to increase air flow metering at lower engine speeds and thus improve instant throttle response.

With a 33mm bore, this carburetor is best suited to smaller four-strokes, in the neighborhood of 250cc, plus or minus. Mikuni suppliers will sometimes set up the carburetor for you if you call them. They'll ask if you have other performance parts on the engine and how you plan on using the bike, then jet the carb accordingly prior to shipping it to you.

As a performance carb, it's not a bad choice. It'll set you back a few bills, but it's unlikely you'll wear it out, and you could probably resell it...

Also take a look at the Emgo carburetor synchronizer.