Red Beard has recently shared a video on the Wildcat 223 engine. In this particular video, he focuses on some essential upgrades that can be made for removing the governor and tuning the engine. We thought it would be helpful to address some common questions and reasons for upgrading the Wildcat using our stage one kit, along with additional parts that can enhance its reliability and allow it to handle higher rpms.
What are the most essential upgrades for a stock Predator 212, Tillotson, Clone, or, in this case, Wildcat 223 engine?
Most will re-jet the carburetor on the governor, replace the restrictive stock muffler with an open header, and possibly add a kart racing muffler. Depending on where the engine is running, the stock air box works well at keeping dirt and debris out, especially if you want to keep the air filter close to the engine. Or, remove the restrictive stock air box for an air filter adaptor and a washable pleated air filter(K&N-Style).
These upgrades usually help the engine start more efficiently and run better, but they are minimal gains, especially if the governor is still intact.
Why would I want to remove my governor from Predator, Tillotson, Clone, or Wildcat Engine?
Engines are designed to operate at around 3600 rpms, and the governor keeps the engine from over-revving. In many cases, the governor speed screws can be adjusted and the governor pinned to allow the engine to hit 4800-5200rpms. In many cases, the engine will surge around 5000 rpms where the governor fights to keep the rpms down.
However, removing the governor may allow the engine to turn more rpm. Higher engine rpms can do two things for your mini bike or go-kart. The faster the motor turns, the more miles per hour you can gain. The other benefit is changing the gear ratio for a higher mile per hour with a lower gear ratio at the cost of acceleration, or you can have a high gear ratio for pulling power(torque) and acceleration at the expense of mph.
From 5200-6000 rpms, most engines will float the valves, which is when the spring can no longer control the valves. That's when we need to consider some vital engine upgrades.
What upgrades do I need if I remove the governor from my Predator, Tillotson, Clone, or Wildcat Engine?
Three essential parts need to be replaced if the engine is going to run without a governor: flywheel, connecting rod, and valve springs.
Why does the flywheel need to be replaced?
The cast iron flywheel is only engineered and rated for stock rpms on any small engine. The danger comes primarily from how the magnet is attached to the outside of the flywheel rather than being part of the casting or embedded and secure in the flywheel. The stock magnet is held on by industrial epoxy or glue and a poor-quality screw. At higher rpms, the inertia of the magnet increases and can come off the flywheel. Imagine its mass and velocity are similar to a 12 gauge shotgun slug. It is extremely dangerous, and the shrouds on these small engines are very thin and become like shrapnel.
What are the options for flywheel?
The most affordable replacement flywheel is a cast aluminum flywheel from the early Hondas, which has been used on the Tillotson 212R and sold as a replacement flywheel for any small engine with a Honda/Clone taper crankshaft. The flywheel has around 18-20 degrees ignition timing, similar to a stock cast iron flywheel. The fins are made into the cast and not made out of plastic like the ones used with the cast iron flywheel. Most importantly, the magnet is made into the flywheel. The flywheel is also lighter, which reduces the probability of it coming apart, and it can help with power and acceleration. These flywheels have been rated for 8500rpms and only cost about $40. (Note: some listings on eBay or Amazon list these flywheels for 10,000 rpms, but they have stolen the information from ARCRACING.com for their billet flywheels. If you read the description, it refers to billet flywheels, not cast flywheels. The info on Amazon and eBay is not accurate)
The next best option is the die-cast aluminum flywheel made by PVL. The PVL flywheel is made from a die-casting stronger than the regular-cast aluminum flywheel. It has fewer fins for less drag and is rated for 10,000 rpms. The flywheel has 28-degree ignition timing, which helps pick up the engine's torque and power, and only costs $90. (note: PVL is a brand, and the die-cast aluminum flywheel is designed for the stock/analog ignitions, not the PVL CDI ignitions)
The best in performance will be a billet aluminum flywheel. Billet flywheels come in many options to use standard or PVL CDI ignitions. We offer three billet flywheels for the Honda/Clone taper crankshaft that use the stock/analog coils: a 3.35lb Flywheel, a 2.7lbs lightweight flywheel, and a 2.5lb finless flywheel. The finless flywheel is only recommended for methanol engines. Each flywheel has 34 degrees of ignition timing for more performance, especially on modified and tuned engines, and costs $105-130.
Why do I need to replace the connecting rod in my Predator, Tillotson, Clone, or Wildcat Engine?
The stock connecting rod is made of cast aluminum and doesn't have rod bearings. Stock rods are not very durable above 6000rpms, and their lifespan can be shortened depending on the level of modifications and engine oil. While rod failure isn't as dangerous as a flywheel failure, it can wipe out the entire engine and all the parts invested in it. For an ungoverned engine, it's best to use a billet rod.
Most EC "billet" rods are forgings that take extruded metal ingot and reshape the grain structure into a semi-finished shape. The grain realignment increases the rod's strength and makes it more ductile, which can result in a lighter and more durable rod.
The Wildcat engine has a flat-top piston that helps with flame propagation and raises the compression over a dish piston when flush with the block's deck. The other benefit of the flat-top piston is the shorter compression height, which allows a longer rod to be used. A longer rod will help reduce the rod angle and slow the piston at the top dead center to minimize wear and friction and improve reliability. Slowing the piston down can also help with scavenging and combustion. The drawback is that in the Wildcat 223, the stock length rod puts the piston at .050" in the hole. EC makes their 8281 rods 050" longer to meet zero decks and raise compression. Most rod replacements are made only to improve the reliability of the rod, whereas the Wildcat also increases the performance. Using the billet rod, the compression is approximately 10.1:1, which is still suitable for pump gas while improving performance.
Why do I need to change the valve springs of my Predator, Tillotson, Clone, or Wildcat Engine?
The stock valve springs for most engines have around 8.5-10 lbs of seat pressure. The seat pressure can change due to the spring or the spring's installed height. In most engines, the install height is around .815-.850. Depending on the cylinder head and if the head is using valve seals. Without enough spring pressure, the valves can lose control or what is known as valve float. Valve Float can happen at higher rpms since the springs have more inertia and can create harmonics in the valve train. You can add shims underneath the springs to increase seat pressure, or the better modification is to add a stiffer spring. Most hemi head will float their valves sooner than the parallel valve(non-hemi) head due to the weight and geometry of the rockers. We recommend using 22-lb springs with stock cams and many mild cams with less than 265 lifts and less than 235 durations.
What is a stage one Wildcat 223?
In Red Beard's video, he shows you how to build a bare-budget Wildcat with the governor removed. He uses the essential flywheel, rod, and valve springs and tunes the engine using our Stage One Kit, a Tillotson PK-3A Carburetor, Billet Velocity Stack/Air Filter, and Air Filter. He also adds an aftermarket exhaust header.
How can an open header on my Predator, Tillotson, Clone, or Wildcat Engine make more power?
The header should be one of the first performance upgrades to your engine. The stock factory muffler prohibits most of the gains from other modifications. So, if you plan to do a carburetor, cam, head, or any further modification, you will see fewer gains than you would if you had an aftermarket header, especially at the higher rpms. The restriction and back pressure from the engine prevent flow from the exhaust. Without flow from the exhaust, the cylinder isn't dispensing its burnt combustion entirely, which contaminates the power cycle and creates resistance on the piston during the exhaust stroke.
The other problem is heat. The stock muffler significantly keeps a lot of heat in the cylinder head when you start raising compression, which can cause the exhaust valve to burn and not seal. It can also lead to head warping if you are not careful.
If you want to keep the stock muffler to reduce noise, don't expect much gains; go with the largest displacement engine you can fit on your application and use a torque converter if you can.
How can carburetor tuning improve power on my Predator, Tillotson, Clone, or Wildcat Engine?
Most will save a little money and only re-jet the carburetor, and you also have that option. The Wildcat 223GT1 differs from stage one when it comes to carburetors. The GT1 uses the stock carburetor and using a larger jet. However, the stage 1 uses the Tillotson PK-3A. The Tillotson PK-3A is the same carburetor as the PK-1B but with smaller jets for the stock Tillotson 212R engine. The PK-1B/PK-3A flows as 3-5cfm more than most stock carburetors and has been barred from competition in the AKRA rulebook due to this unfair advantage.
The PK-3A carburetor is already optimized for a factory air box and stock muffler. The stock jets of a typical stock Hyuai, Ruixing, SP, and other factory emissions-controlled carburetors is a .014 pilot and .028 main, and the Tillotson PK-3A is a .019 pilot and .032 main. The bigger pilot will help with start-up and acceleration, and the main will improve top-end performance. Usually, with emissions carburetors, you are only adjusting the main because there isn't an idle mixture screw to smooth out the idle when a bigger jet is used.
Since the Wildcat is a slightly bigger engine with higher compression, an open header, and a velocity stack, you may need a larger jet for the main. Somewhere between .035-.038, depending on your atmospheric conditions. Red Beard's test was with a .037 main jet. We recommend leaving the pilot alone unless you have a dyno to test. The pilot can make a big difference in power but will run rich at low speed, leading to spark plug fouling. We don't recommend using spark plugs in a very cold heat range like the Autolite 3910X. Use a plug in your current heat range or one range colder and gap the plug between .028-.032".
Carburetor tuning may be required for changes in engine combination(cam, compression, displacement, cylinder head, etc.) or atmospheric conditions(humidity, altitude, ambient temperature, etc.).
Why must I replace my stock Wildcat ignition coil with a non-rev limiting coil?
The first batch of Wildcat engines had rev-limited coils from the factory. The redundancy for rpm control is becoming more common to prevent tampering with the mechanical governor since the stock cast iron flywheel becomes dangerous, much past stock-rated rpms.
Since these engines were meant to be modified for sanctioned mini bikes and go-kart racing, the later batches were built with non-rev limited coils. Since both engines are in circulation, we include non-rev limited coils in our Wildcat stage kits.
We use the high-output ignition coils that we spec and sourced for the Tillotson 196R and Tillotson 212R racing engines(these coils are not the same as the 212E). These coils produce 2mJ more energy and 4kV more than standard coils. You can usually measure the diameter of the coil body, which is larger due to the additional coil windings than a standard Predator or Clone coil.
What is the performance gain from a stock Wildcat 223 to the Stage 1 Wildcat Build Build?
Stock: 7.74Hp at 4200rpm – 10.2Tq at 3800rpms
Stage 1: 9.62Hp at 4600rpm – 11.51Tq at 4200rpm
Gains: +1.88hp(24% gain) and +1.31Tq(13% gain)
Dyno testing performed by Red Beard's Garage
Let's take a closer look at the numbers and the dyno charts. The torque improved by 1.31ft-lbs, and peak torque moved from 3800 to 4200rpms, where peak power was for the stock Wildcat 223. The improvements didn't hurt the torque below 4200 rpms; the torque curve looks nearly identical and slightly more prominent. The engine still makes more than 10.2ft-lbs at 3800rpms. Now, the engine is pulling harder and farther than before. Peak torque moved 400rpms because the engine became more efficient above 3800rpms.
The horsepower also improves by nearly 2hp. 1.88hp is a gain of 24.4% over stock. It also moved peak power from 4200 to 4600 rpms. Power is increased by the carburetor tuning and increased compression. Still, the exhaust helps the engine breathe better to move that power higher in the rpm range, which results in additional power.
We also want to look at how the overall power band improves. The Stock Wildcat made 7.74hp at peak, but stage one Wildcat makes 8hp from 3800-3900rpms to about 5700rpms. Even at the end of the run, the Wildcat makes more power at 6100rpms than a Predator 212 makes at its peak. The peak torque of the stock Wildcat was 10.2ft-lbs, but the stage one makes 10ft-lbs from 3700rpms to about 5000rpms.
Another point is the comparison to some of the other engines and tests Red Beard has made on his dyno.
How does the Stage 1 Wildcat Budget Build compare to other built engines?
The Ghost 212 has a 22mm slide carburetor and about .025-.030" more lift on the camshaft. The Ghost makes only 0.10ft-lbs more torque and 0.28 more horsepower. The Ghost has a slight edge above 5000rpms but is rev-limited to 6100rpms.
When Red Beard tested the VM22 Chikuni, Genuine Mikuni VM22, and a TM24 carburetors on a Predator 212 with a billet flywheel and 18lbs springs, peak torque was around 11.5 at 4300-4400rpms. The Wildcat with a stock-size carburetor makes as much torque but almost 200 rpms sooner. There is a more significant variation in horsepower depending on the carburetor. The genuine VM22, which is 22mm, makes 10.53hp at 5300 rpms. The VM22 Chikuni is 26mm and flows better than the 22mm Mikuni, which made 11.31hp at 6500 rpms. The additional flow allows the power to be carried further. The TM24 at 24mm flat slide flows about the same as the 26mm Chikuni made 11.92hp at 6400rpms. The horsepower is 0.90-2.3hp, but those gains are from carburetors that flow 65-150% more air. It shows how vital airflow is compared to displacement, compression, etc.
The next build is our Stage 2, aka "Ghostbuster" kit, where we add a billet flywheel, 22mm slide carburetor, and our TTS-647 Camshaft. We're expecting better gains thanks to better airflow.
Wildcat Stage 1 Parts List:
$39.99 - Cast Aluminum Flywheel
$84.95 - Forged Connecting Rod
$8.99 - 22lbs Valve Springs
$40 - Header
$72.99 - Stage One Kit:
• PK-3A Tillotson Carburetor
• 327FA - Velocity Stack
• 642 Air Filter
• 138190045 Non-Rev Limiting Ignition Coil
Total Parts Cost $246.92
Engine Cost $179.99
Total Build Cost $426.91(cost may vary depending on additional accessories needed for your specific build)
