Buying go kart parts online can be a little bit tricky sometimes. A lot of parts websites have minimal details. Other websites have a lot of technical details and measurements but don't provide any model specific information. And even when you use a site like GoKartMasters with clear information on each part, sometimes it's difficult to know which model your go kart is. Understanding the different models and what is different between each model is key to making sure you buy the correct parts.
If you own a Trailmaster mini go kart, you need to make sure you know exactly which model you own. There are a lot of different options. A lot of parts are the same across all of the minis, like the steering wheel, key switch, air filter, etc. But other parts can be different, like carburetors, brake calipers, seatbelts, and clutches.
The original mini model (without a plus or +), were built with a 10 tooth centrifugal clutch. If you have a Trailmaster Mini XRS, Trailmaster Mini XRX or Trailmaster Mini XRX-R, the original clutch had 10 teeth. These models would have all originally come with 13" tires on the rear.
The plus models (with + in the model name), were built with a 12 tooth clutch. When the plus models came out, they were designed with a wider rear axle and larger 16" tires on the rear. In our opinion, the clutches should have remained the 10 tooth to maintain the low end torque needed to get those bigger tires moving. For an unknown reason, the factory builds them with 12 tooth clutches.
All of that being said, the centrifugal clutches and upper chains across all Trailmaster Mini go kart models are the same gauge and length, which mean the clutches are interchangeable. In fact, we recommend that everyone uses the 10 tooth clutch regardless of which model you own.
If you find yourself having issues with clutches burning up regularly, axle issues, or just general difficulty for your go kart to take off from a stop, it's time to replace the 12 tooth clutch with a 10 tooth clutch. We sell both because some people just want factory original parts.
Keep in mind, the plus axles will fit the non-plus go karts, so it is possible that your axle has been replaced and you may have a hard time identifying whether you have a plus model or not. But there's no need to worry about this when you're identifying which clutch you need since either clutch will fit.
So, if you have the question "what size clutch fits my Trailmaster mini go kart?", the answer is: a centrifugal clutch with a 420 sprocket with either 10 or 12 teeth. It's up to you which one you want but GoKartMasters recommend the 10 tooth.
