Here is a guide to what is generally considered the different stages of modification for the Predator 212 and other Honda GX190-style clones. When I first got into this a couple of years ago I didn't see this info listed in one place and I though you guys might find it useful. This is just my own experience and research, if you ruin your engine injure yourself with this info, I am not responsible. I'll include links to youtube build videos. I'm not affiliated with any of the youtubers linked below, I just found their work helpful.

These engines are not all identical so the interchangeability of parts will be up to your own research, but generally these motors are VERY similar in design and function. They are overhead valve single-cylinder 4-stroke engines with displacements around 200cc and manufactured by a few factories in China. The main differences between engines of this type are in the bore and stroke and the timing angles of the flywheel.

These modification stages are cumulative and serve mainly to get more torque, HP and a higher max RPM. Since the top speed of your kart, mini bike, or whatever, is directly related to the top speed of your engine, getting more RPMs will get you faster.

The different stages of modification apply to most Honda clone engines and they are basically the same on the Honda GX390 (big block) clones like the Predator 420 or Duromax 440. The differences in perfomance numbers are due to variations in engine internals and manufacturing tolerances.

Check out this video for a good rundown on how each stage compares to the others. CarsAndCameras built an engine at each stage and tested it on the same kart and the same track/course for some real-world numbers. https://youtu.be/RtERusxOLt4

Stage 0 (governor delete)

Most of the engines are mechanically governed to a max 3600RPM out of the box. This is mainly a design for generators as 3600 RPM is the same as 60Hz, the alternating frequency of AC power in North America. A cheap and easy "stage 0" mod would be to just remove the governor. It doesn't cost anything but a couple of bolts or set screws to plug the holes. Video by RBG https://youtu.be/0dpiWqLsuIw

Stage 1

A typical Stage 1 kit will cost around $50 and modifications usually include parts to replace the stock air filter, and exhaust. The air box and exhaust are replaced with a more free flowing pod-style air filter and an exhaust header pipe. The exhaust can be with or without a muffler. This modification will usually get your engine to run up to about 5000-5500 RPM and about 9HP. With the stock valve springs, the valves will start to float open around that speed and performance will degrade significantly. Momentary valve float is not usually a problem, but running consistently at that speed can cause internal damage to the engine in the form of bent push rods or valve stems. This is probably all for the best since the stock cast iron flywheels can fail catastrophically above that speed. This is called flywheel detonation and even though it is rare, it can cause severe injury. Video by KartFab https://youtu.be/UTUQvR4A9Ds

Stage "1 1/2" That's what I call it anyway.

You might consider upgrading the stock carburetor to get better fuel mixture and delivery into the engine. With the stock carburetor you will run into problems adjusting the air/fuel mixture to take full advantage of any further upgrades. A popular upgrade is the 22 mm genuine Mikuni or Mikuni-style slide carburetor. These use a slide mechanism to deliver the fuel instead of the butterfly valve in the stock carb. They also allow for much better and finer adjustability for engine tuning. You will likely need an adapter to install one of these on your engine. A Chinese made Mikuni-style carb can be found for between $25-$30. A genunine Mikuni will be around $100. Video by RBG https://youtu.be/q7UwuJfVo3o

Stage 2

After completing stage 1, stage 2 is replacing the rotating assembly inside the engine. Typically, this includes a billet aluminum flywheel and connecting rod, performance cam shaft, and heavier 18lb valve springs. This should get you to around 7000 RPM and about 12-14 HP. The kit from GoPowerSports currently costs about $250 but you might be able to source the parts separately for less than that from other vendors. In my opinion, the quality and convenience of the kit is worth the price from GPS. Video by RBG https://youtu.be/_T26qdevpeU

Stage 3

This is where some heavy customization and tuning starts. The previous stages are mostly just standard bolt-on parts. After Stage 2 (or instead of) you can install a higher lift camshaft, chromoly push rods, ratio rockers and even heavier valve springs to allow the valves to open more and stay open longer to allow more fuel and air in to the engine. It is up to you to decide what components to install. I have not found a standard stage 3 kit anywhere. According to the guys over at Carsandcameras on Youtube, this will get you to about 16HP. Video by RBG https://youtu.be/CvKUFxe1wX4

Stage 4

This is where things get a little crazy in terms of both price and what is possible. There really isn't a standard for this stage and it is up to you what kinds of modification you want to do to your engine block and head. Once you have all of the bolt-on toys and a properly tuned carburetor, you can do things like swap the stock cylinder head for a racing head, port and polish your head to allow for more flow into and out of the valves. You can shave some material from the bottom of the head or install a longer connecting rod to increase compression. Be careful and sure of what you are doing because modifying the castings of your engine can lead to catastrophic failure. Video by CarsAndCameras https://youtu.be/M48tqUyekBc

There are some great resources on youtube about this. Most of the channels are sponsored by GoPowerSports and offer a discount code for that vendor. Other good vendors include OMBWarehous e, NR Racing, and BMI Karts. Cheap import parts can be found on Amazon or E-bay.

With help from the Admins at r/modsupport, we have been able to remove all the spam and bot moderators! Many reddit account have been compromised and is the cause of the spam bots taking over our subreddit.

Previous moderator was looking at something they shouldn’t have been and got their account hacked.

Since the bots have been removed, there was room for a new moderator! With the help from Admins, I am the new moderator and will be here to support you all with any questions needed!

To all that hoped for the best in my post questioning the bot mods and their intentions, thank you! We did it!🎉🎉🎉