Why the HRM chain drive Jack Shaft System is a better option than a belt drive Torque Converter
The HRM Coleman CT200 Performance Jack Shaft system has proven to be a much more durable drive system than using a 20-30 series TC unit. And unlike the commonly installed TC systems. It is a direct bolt on requiring no cutting of the frame or special engine mounts to make it fit. The Comet style 20-30 series Torque Converter systems also do not lend them selves well to engine mods. It is common for them to slip excessively when stalled out on a hill. And it will cause the belt to smoke, or even come apart in this situation. And this will even happen with a stock 6.5 HP engine.. The TC system does not like water, sand or mud. This will quickly degrade there performance and life.
Dated 20-30 series Torque Converter design
All Modern Street Scooter’s run there belt system well sealed from the elements. The small belt is kept tight between the pulleys at all times to prevent slippage. Unlike the 20-30 comet’s small belt which is loose and slipping whenever you are at idle, or taking off from a stop. And not sealed from the elements. Most modern Scooter TC systems also have an additional shoe type centrifugal clutch in there drive system.This supplies the clutch action at idle and for taking off from a stop.( Instead of wearing out there belt with all the slippage).They use a roller weight style front pulley. The operation is low friction and smooth. It applies a strong clamping force to the drive belt. Modern ATV’s and Snowmobile TC’s use much larger belts and good roller clutches in there TC system.This is to take the abuse of using the slipping belt as the clutch. Belt replacement is a common service routine.
Is the 20-30 series TC install worth Installing on your mini bike?
The 20-30 series TC does not fit well in most MIni Bikes. In almost all cases it will require frame or mount mods to get it to fit. Our experience is that the TC usually works OK when first installed. It will impresses you with the top speed increase of your stock motored bike. But then it degrades itself from there. It will need to be serviced often to keep it working correctly. Especially if used off road. There are far more moving parts to wear out. And they will typically end up slipping or developing a grabby engagement. Or even worse smoke and eat the belt. Sure they can be serviced and the belt replaced. But this is a little more involved than servicing a chain drive system.
196cc and 212cc Engine Modifications that are best suited to your drive system
Along with the increased durability of the HRM Coleman CT200 Performance Jack shaft system. Performance wise, It allows the engine to rev out through it’s entire rpm range. This is a huge advantage when removing the governor and installing stiffer valve springs. The governor removal, flywheel, rod and stiffer valve spring install is an all time favorite mod to do to these engines. And it is kinda pointless to do when running a TC system. Here is why. The Torque Converter system’s design restricts your engine RPM down close to what the stock engines mechanically governed rpm is. And does this throughout the entire acceleration/ gear ratio changing process. If you try to adjust spring rates, or spring positions. In hopes of higher rpm’s to match your modified engines rpm capability’s. The more they will slip. The TC system also has very large heavy pulley’s. The heavy primary clutch pulley hangs out past the end of the crankshaft when mounted. I witnessed numerous cases where the pulley came loose and damaged the crankshaft. The crank bolt that holds this pulley should be checked often.
Torque Converter power ratings
With the 20-30 series TC’s HP limitations. It kinda takes the fun out of being able to inexpensively modify your engine. When you use the right parts. You can easily double the stock engine’s RPM and HP. And all this with bolt on parts! A stock 196 cc engine with a good header, performance air filter and properly re-jetted carburetor’ can easily make over 8-9 hp. This is at the manufactures suggested limit for these TC units. Yes there is a reason why they are not used in the Kart racing industry. They simply will not hold up or perform as well on the race track as a chain drive centrifugal clutch system. So If you want something much more reliable. Even for your stock engine. Then the Coleman CT200 Performance Jack Shaft System with quality chains will handle all the mods you want to through at your engine.. Or It will give you piece of mind that you have a much more reliable drive system for your stock engine. Keep your chains lubed properly and your clutch serviced and you will have years of proven reliability!
Our experience servicing 20 and 30 series Torque Converters
After being a Baja Motorsports warranty repair center. Working on and owning vehicles equipped with the 20-30 series Comet style TC. My advise is this. If you are going to use a 20-30 series Comet style TC belt drive system. Especially the cheap China knockoff. Only use it on a stock or lightly modified (power up kitted) 6.5 hp bike. Something used mainly for cruising around and light trail riding. And be prepared. You are still very likely to have problems at some point. So strap on an extra belt and some tools to your rack if you plan on taking long trail rides. Most importantly you must avoid stalling out on hills or in rocks or sand, and leaning on the throttle hard. This will cause the belt to slip badly, smoke and sometimes come apart.. And it is actually a fire hazard when it does this. I had a customer in the shop years ago with a TC equipped Go kart. He shared a potentially very bad experience with me. His kid got stuck in a field and smoked the TC belt while trying to negotiate a small hill.The smoking rubber fragments flying out of the cover caught the dry grass on fire! Luckily they were able to stomp it out before a major fire started.
We have been manufacturing and selling the PMR, HRM Jack shaft system for over 9 years now. They have been tested and used for many applications including Race Karts, JR Sprint Cars,Yard kart projects, Mini Bikes, Motorized Bicycle, Drift Trike projects and more. Gear ratios can be easily adjusted with different Jack Shaft sprocket options. Jack shaft sprockets are easy to change. Rear sprockets are not. One of our favorite mods is to gear the bike lower for better take off torque. And do the proper mods to increase the engines RPM capability and top speed.
Jack Shaft pics.
TC belt drive pic. (approx’ 30 min run time with mildly modified stock engine.)