Complete Guide for Coleman BT200X Upgrades/Mods

We have already created guides on Predator 212 upgrades and Coleman CT200 upgrades and even though the engine used in the BT200X is no different from other 200cc Mini Bikes, there are a few performance parts that are different from the ones used in CT200u so that it can fit the body of BT200X.

And for that reason, we have created this guide with all the parts listed with the expected top speed gain from each part and their functions described. This will be a very beginner-friendly guide so you won’t have to have any engine-building experience from the past.

Torque Converter

Changing your centrifugal clutch for a Torque Converter/CVT is the easiest way to increase your top speed. The torque converter is just a transmission system, it will not increase the power that your engine produces since it’s not even inside your engine.

It will however allow you to change the gearing of your BT200X which is originally set to 10:1. With a torque converter, you can easily change it to 6:1 without damaging the torque converter.

This change in gearing will result in your top speed increasing 5/3 times your original top speed. Taking the top speed from 20 mph to 34-35 mph.

Best Torque Converter for BT200X

Note: Some Minibikes come with a 3/4″ Crankshaft and some come with a 5/8″. BT200X most of the time has a 5/8″ Crankshaft, in such cases you’ll need to get a 5/8″ adapter sleeve along with the torque converter. Measure your Engine’s crankshaft before you order.

Installation

Installation can seem complicated, mainly because you need to cut the frame in the process. However, if you do have an extra $40 to spend, I suggest you get a Riser Plate from OMBwarehouse, it will eliminate the cutting process.

For the complete step-by-step installation process, you can watch some youtube videos (like this).

Note: Cutting the frame’s rear end will decrease your minibike’s frame strength and therefore I highly recommend you to get a riser if you can afford it.

Governor Removal

All the 200cc Honda clone engines are limited to 3600rpm, in fact, every industrial engine is governed at 3600 this is because most industrial applications run smoothly at 3600 rpm. But we don’t need it on a minibike.

And this is why almost every engine builder removes them as the first step. You can check our article on how to remove the governor on small engines for a step-by-step guide.

You can expect some 10-15 mph gain with the governor removed. However, the engine is still limited to 5500 rpm due to stock valve springs having low stiffness (more on that later).

Stage 1

Stage 1 Kit includes an Air Filter, Exhaust, and larger main jet along with the upgraded spark plug. This kit essentially allows your engine to breathe more air in, combine it with more fuel and burn more air-fuel mix and then remove the burnt gas of the gas with better exhaust.

You won’t see any huge gain in speed with this kit but you’ll definitely see an increase in power and torque which will allow you to get to top speed quickly (improve acceleration)

I do not recommend you to buy all the parts of the stage 1 kit from a supplier (like GPS or OMB). Because if you get the exhaust from these kits, they will create spacing issues with the BT200X frame and won’t allow you to install the muffler. Rather buy them separately, all the items and links listed below.

Caburetor Upgrade

Once you have the stage 1 kit installed, a Mikuni Carb will take your engine to the next level! You can check our list of best carb upgrades for 200cc minibikes, however, I’ll also list the best one in this article.

Note: You’ll need to buy the main jet kit for Mikuni and change to the #120 main jet to get the best out of Mikuni carbs. Additionally, you’ll also need to install it properly and tune the carburetor. This is not a plug-and-play, it requires some work from your side.

Billet Rod & Flywheel

To proceed further and take your engine past 5500 rpm, you need to replace some stock parts that won’t hold up at those speeds. These parts are the flywheel and connecting rod. Note, the upgrades to rod and flywheel are expensive but you cannot proceed without them. It can put your safety at risk if you proceed without the billet flywheel and billet rod.

Valve springs

As mentioned before, the OEM valve springs limit the engine to 5500 rpm. To go past it you need a stiffer valve spring. It is important to note that the installation of valve springs requires you to adjust the valve lashes and other parts. You must be ready to learn a lot more about your engine if you proceed with a stiffer spring.

Further Mods

There is a lot more than you can do with these engines, but if you’re a beginner, a stage 1 kit along with a Torque converter and Mikuni Carburetor will already take you close to 50 mph! Which is more than what most people desire.

If you still want to proceed, you can change the cams, install bigger valves, increase compression, and a lot more. We have covered it in more detail in the Predator 212 mods guide and there won’t be any point in repeating the same points here so you can check that article for more details.