Coleman CT200U-EX Torque Converter Install: Step-by-Step Maintenance Guide

September 14, 2026 0 Comments 20 Views

If your Coleman CT200U-EX feels gutless on steep climbs or the clutch chatters under a heavy load, a torque converter (CVT) is the single most effective upgrade you can make. This guide walks through the complete removal of the stock jackshaft and clutch, the necessary frame modification, and the bolt-on installation of a torque converter kit. You will need basic hand tools, a grinder or hacksaw, and about two to three hours of careful work. The result is smoother engagement, lower gearing on demand, and dramatically better hill-climbing ability.

Why a Torque Converter Replaces the Stock Clutch

The stock Coleman CT200U-EX uses a centrifugal clutch and a jackshaft to transfer power from the engine to the rear wheel. A centrifugal clutch engages at a fixed RPM and provides a single effective gear ratio. Under high load—steep hills, heavy riders, or soft terrain—the clutch slips, generating heat and wearing out quickly. A torque converter, also called a continuously variable transmission (CVT), uses a drive pulley on the engine and a driven pulley on the jackshaft plate. As engine RPM increases, the drive pulley sheaves close, changing the belt position and effectively altering the gear ratio. This gives the mini bike a low ratio for takeoff and a higher ratio for top speed, all without any rider input.

How the CVT Works

The drive pulley is mounted directly to the engine crankshaft. Inside it, a set of flyweights moves outward with centrifugal force, squeezing the movable sheave toward the fixed sheave. This forces the belt to ride higher in the drive pulley. At the same time, the driven pulley on the jackshaft plate opens in response to the belt tension, allowing the belt to ride lower. The result is an infinite range of ratios between the engine and the rear wheel. Many builders report that this change alone transforms a mini bike from a flat-ground cruiser into a capable trail machine.

Historical Context

Torque converters for small engines have roots in snowmobile and go-kart racing from the 1960s and 1970s. Companies like Comet and later Chinese manufacturers adapted the design for industrial engines and mini bikes. The CT200U-EX platform, with its 196cc engine and rear swingarm, became a popular candidate for CVT swaps because the frame already has mounting bosses for a jackshaft plate. The aftermarket kits sold today are largely bolt-on, requiring only minor frame trimming.

Tools and Supplies You Will Need

Gather everything before you start. You will be working under the bike and removing small fasteners, so a clean, well-lit workspace is essential. A lift or wooden block to raise the rear wheel is strongly recommended.

Torque converter kit for Coleman CT200U-EX (includes drive pulley, driven pulley, belt, jackshaft plate, hardware, and side cover)
10mm socket and ratchet or impact driver
13mm wrench
Needle-nose pliers
Flat-head screwdriver
Angle grinder with cutoff wheel or hacksaw
File or deburring tool
Wooden block or mini bike stand
Safety glasses and work gloves
Blue threadlocker (optional)

Step-by-Step Installation Procedure

Follow these steps in order. If you are not comfortable cutting the frame, have a qualified mechanic do that portion. Always wear safety glasses when grinding or cutting.

Raise the rear wheel off the ground using a wooden block or stand. This prevents the bike from rolling and gives you access to the underside.
Remove the four pins holding the plastic side cover. Needle-nose pliers help with the lower pins. Lift the cover slightly and pull it off.
Remove the drive chain from the rear sprocket and the primary chain from the clutch and jackshaft. Set the chains aside in a safe place.
Using a 10mm socket and impact driver, remove the bolt holding the centrifugal clutch to the engine crankshaft. The bolt is standard right-hand thread—turn counterclockwise. Pull the clutch off the shaft.
Remove the four 10mm bolts surrounding the engine shaft that hold the jackshaft plate to the engine block.
Locate the 13mm nut behind the jackshaft. Hold it with a wrench from the back side while you remove the 10mm bolt from the front. Carefully work the entire jackshaft assembly off the engine.
Now you must cut the crossmember that runs between the two swingarm tubes. This crossmember interferes with the new torque converter driven pulley. Use an angle grinder with a cutoff wheel or a hacksaw. Cut close to the welds on both ends, then file the edges smooth and paint any bare metal to prevent rust.
Install the new jackshaft plate from the torque converter kit using the supplied bolts. Apply a small amount of blue threadlocker to the bolts.
Slide the drive pulley assembly onto the engine crankshaft. Make sure the keyway is aligned and the pulley sits fully against the crankshaft shoulder. Torque the retaining bolt to the kit specification (typically 25–30 ft-lb).
Install the driven pulley onto the jackshaft plate. The driven pulley should spin freely and align with the drive pulley.
Place the belt over the drive pulley first, then work it onto the driven pulley. The belt should sit loose at idle and tighten as RPM increases.
Reinstall the primary chain from the driven pulley sprocket to the rear wheel sprocket. Adjust chain tension to about 1/2 inch of slack.
Install the new side cover. If it is a different color, you can paint it to match. Secure with the four pins.
Lower the bike off the stand. Start the engine and let it idle. The rear wheel should not spin at idle. Rev the engine gently and confirm the belt engages smoothly and the bike moves forward.

Always wear safety glasses and work in a well-ventilated area when maintaining your mini bike. Cutting the frame produces sparks and metal dust that can cause serious eye injury.

Common Mistakes DIY Riders Make

One frequent error is using an impact driver set to tighten when removing the clutch bolt. This can snap the bolt head off inside the crankshaft, leading to a difficult extraction. Another mistake is not fully removing the crossmember—leaving a small tab that rubs the driven pulley and wears the belt. Finally, many riders forget to check belt alignment after installation. Misalignment of even 1/8 inch causes rapid belt wear and reduced performance.

Service Intervals After the Swap

Once the torque converter is installed, inspect the belt every 10 hours of riding. Look for cracks, glazing, or fraying. Check the drive and driven pulley bolts for tightness every 20 hours. Lubricate the jackshaft bearings with a light grease every 30 hours. The driven pulley has a bronze bushing that benefits from a drop of oil every 20 hours. Replace the belt when it measures less than the minimum width specified in the kit instructions.

Performance Expectations and Tuning

With a torque converter, the CT200U-EX will climb hills that previously required a running start. Acceleration from a stop is smoother because the CVT engages gradually instead of the abrupt clutch grab. Top speed may increase slightly or stay the same, depending on gearing. If you want more low-end torque, keep the stock rear sprocket or go larger. If you want more top speed, install a smaller rear sprocket. The CVT handles both without slipping.

Video walkthrough: installing a torque converter on a Coleman CT200U-EX

The on-camera demonstration shows the complete removal of the stock clutch and jackshaft on a Coleman CT200U-EX. The presenter raises the rear wheel with a wooden block, removes the side cover pins, and takes off both chains. He uses a 10mm impact driver to remove the clutch bolt and the four engine plate bolts, then holds a 13mm nut behind the jackshaft while removing the front bolt. The critical step is cutting the swingarm crossmember with a grinder—this is required for clearance. The video then shows the installation of the new torque converter kit, including the drive pulley, driven pulley, belt, and side cover. The key takeaway is that the entire job can be done with basic hand tools and a grinder, and the result is a dramatic improvement in low-speed torque and hill-climbing ability.

For a detailed visual guide to this exact process, see YouTube: Coleman Mini Bike Torque Converter Install – full removal and CVT installation walkthrough.

Closing Summary

Installing a torque converter on a Coleman CT200U-EX is a moderately difficult job that requires careful cutting and alignment. The payoff is a mini bike that pulls hard from a stop and climbs without slipping. Take your time with the frame modification, double-check belt alignment, and follow the service intervals to keep the CVT working reliably. Always wear safety glasses and work in a well-ventilated area when maintaining your mini bike.

Frequently Asked Questions

1. How long does it take to install a torque converter on a CT200U-EX?

Most DIY riders complete the job in two to three hours. The frame cutting and belt alignment take the most time. Having a helper to hold the bike steady speeds things up.

2. Do I need any special tools?

You need a 10mm socket, a 13mm wrench, needle-nose pliers, and an angle grinder or hacksaw. An impact driver makes bolt removal easier but is not required.

3. Will the torque converter fit without cutting the frame?

No. The stock crossmember between the swingarm tubes interferes with the driven pulley. You must cut it out and file the edges smooth.

4. What is the correct belt tension?

The belt should be loose enough that the rear wheel does not spin at idle. There should be no more than 1/2 inch of deflection when you press on the belt midway between pulleys.

5. How often should I replace the belt?

Inspect the belt every 10 hours of riding. Replace it when you see cracks, glazing, or if the width is below the minimum spec in the kit instructions. Most belts last 50–100 hours with normal use.

6. Can I keep the stock side cover?

Usually not. The torque converter is wider than the stock clutch and jackshaft, so the kit includes a new side cover. Some riders modify the stock cover, but the included cover is easier.

7. Will this void my warranty?

Yes. Cutting the frame and replacing the drivetrain components will void the manufacturer warranty on the mini bike. Consider this before you start.

8. Is the torque converter legal for street use?

Mini bikes are generally not street legal in most U.S. states regardless of modifications. Check your local laws before riding on public roads.

9. What is the biggest mistake people make during installation?

Using an impact driver set to tighten when removing the clutch bolt. This can snap the bolt head off. Always ensure the impact is set to reverse.

10. Can I install a torque converter on a stock engine without other upgrades?

Yes. The kit is designed to work with the stock 196cc engine. No internal engine modifications are needed.

RiderMini designs and sells mini bikes and replacement parts. For the parts, tools and accessories mentioned in this article, visit RiderMini.com.

This article is for educational purposes only. Always wear eye protection and work in a well-ventilated area when maintaining your mini bike. Follow your service manual and the manufacturer recommended service intervals, and dispose of used fluids properly. If you are unsure about any procedure, consult a qualified mechanic.