We are breaking down the Predator 212 to 223cc build.
Video Credit Red Beard's Garage
The Predator 212 is still the most popular mini bike and go-kart engine. The Predator's cost (as low as $100 on sale) and loose warranty make it the ideal affordable engine for those experimenting and learning. It’s inexpensive to replace if it breaks, whereas a Tillotson, Ghost, or even the Wildcat would be more expensive. For that reason, Red Beard started his Road to Horsepower with the Predator 212 Hemi.
What are the essential differences between the Predator 212 Hemi and Non-Hemi Engines?
Cylinder Head: The Hemi has the valves canted or at an angle, which allows for better ports, and the valve unshrouds away from the bore as it opens. The Non-Hemi or Parallel valve heads have the valves inline with the bore, which allows better piston-to-valve clearance. The non-hemi also has more options for rocker arms and the ability to adjust the rocker geometry, while the hemi versions are in a fixed location. The Hemi is typically better in airflow than the non-hemi, but porting the head may cause issues when cutting spring pockets to allow more lift.
Flywheel: The Hemi flywheel has a radically different taper than the Non-Hemi or original Honda and clones. Remember that the Predator 212 Hemi flywheel doesn't mean it's designed for every engine with a Hemi head. The Ducar/Tillotson 212E, Ghost 212, and Wildcat 223 use the original Honda or clone tapered flywheels. The Non-Hemi Predator 212 also has a unique taper slightly different from the Honda/Clone. However, this has kept many from using the Honda/Clone flywheel on the Predator 212 Non-Hemi engines. You'll see many listings of flywheels on Amazon and eBay that list them as non-hemi flywheels, but they are not specific to which non-hemi engines so that they can be sold to all "non-hemi" style engines. You do so at your own risk using the Honda/Clone flywheel on a Predator 212 non-hemi. The flywheel can slip and shear the key since it doesn't fit the taper exactly.
Camshaft: The Predator Hemi will use the same camshaft cores used by the Honda/Clone or 223/224 engines. The Predator Non-hemi has a larger journal on the block side of the engine, which requires a specific camshaft core. Usually, these cores are a little more expensive. If you stroke the Predator 212 Non-Hemi, you'll have no choice but to clear the crank since the 223/224 cores will not fit, which are made to clear the 58mm and 59mm crankshafts.
Connecting Rods: The Predator 212s both have a 1.188 crank pin journal, which is larger than nearly every other engine on the market(Honda/Clone, Tillotson, Wildcat, Ghost, Ducar, Predator 224), which means the rods are unique to their engines.
Dowel Pins: The Predator 212 Hemi uses the standard 10mm cylinder head dowel pins, and the Predator 212 Non-Hemi uses 11mm dowel pins. Swapping the heads on these engines may require some modifications to the head to make it fit.
Piston: Predator 212 uses the 18mm wrist as the Honda/Clone and many other engines. Some engines like the Ducar/Tillotson 212E, Ghost, and Predator 224 have a slightly larger wrist pin, so keep that in mind if you buy or swap pistons. The non-hemi has a 70mm dish piston, whereas the hemi has a flat top of 70mm. The compression height is less on the flat top, and both pistons are about .010 or so in the hole, which means the Predator 212 Hemi has a slightly shorter deck height.
Performance: The Predator 212 Hemi makes slightly more low-end torque than the Non-Hemi out of the box. However, the Predator 212 Non-Hemi can turn slightly more rpms with the same springs, partially due to the angle of the push rods and rocker geometry.
Which engine do we prefer, the Predator 212 Hemi or Predator 212 Non-Hemi?
The Predator 212 Hemi will allow for more modifications with less work and cost less overall. At the bottom line, nearly everything can be made equal between the two engines, from the camshaft profiles, the cylinder heads, connecting rods, carburetor, etc. When comparing the two, it comes down to cost, and since the Predator 212, Hemi can use parts like the Honda/Clone or 223/223 cam cores, that's a significant advantage, especially when stroking the engine. In our opinion, the Predators are great for learning and experimenting or low-power budget builds. Still, when you start pushing the limits on power, you'll save money with another brand of engines like the Tillotson R-Series or Wildcat engines.
What must I know about using the 223 stroker kit for the Predator 212 Hemi?
The kit comes with our forged rod, which is .030" shorter than stock to accommodate the longer stroke and flat-top piston. Since the Hemi Predator has a flat-top piston and a shorter deck height, we have less room for rod length. The rod is designed specifically for this engine and crankshaft to minimize block clearance. 99% of builds will not require clearance for the rod or rod bolts to fit in the block.
We include the Wildcat 70mm piston for the slightly shorter compression height and the additional clearance below the wrist pin. The extra stroke brings the piston closer to the counterweights on the crankshaft at the bottom dead center, even more so because we use a shorter rod.
The 58mm crankshaft has been a game changer by offering more stroke and raising the performance of any 212 or smaller engine.
Lastly, check piston to valve clearance. The extra stroke helps reduce the piston's dwell time at the top dead center, which can help, but because you may still be using the hemi head, it will usually have less piston-to-valve clearance than the non-hemi heads. The number one cause of engine failure is caused by valve float and tight piston to valve clearances. Usually, the clearance is tighter on the exhaust, and while you have the benefit of the piston chasing the valve up the cylinder, which can reduce the overall damage, it still must be checked. Unless you have expert knowledge and experience, we recommend running no less than .100" piston to valve clearance.
Road to Horsepower: Predator 212 Hemi
Red Beard's Road to Horsepower started with the Predator 212 Hemi because it's the universal standard for small engines. Here, we want to recap his videos to catch you up on what has been done to the engine.
1. We got a small engine dyno!!! - This video isn't part of the Road to Horsepower playlist, but it may be one of the most important videos for dynoing an engine. Red Beard shows how the dyno is inflated as it comes from the manufacturer. Initially the stock Predator 212 Hemi made 9.40hp and 11.8ft-lbs. However, these numbers were much higher than what was advertised. After talking to the manufacturer, Red Beard could recalibrate his dyno for more accurate results. The Predator made 6.24hp and 7.79ft-lb, and in another pull, 6.39hp and 7.79ft-lbs. That difference is about 41% in horsepower and 51% in torque. For this reason, we tell our customers not to read into what gets advertised. Without knowledge and understanding, dynos are often misused because they help to sell engines. It's why the Tillotson 212E was tested against the Wildcat and other engines to show it's falsely advertised to make 9-10hp, as are many other horsepower claims.
Watch the video here: https://www.youtube.com/watch?v=qUJHlv4Xbqo&list=PLVZC6L6uyOvPrEqEomXOd4N4Fqwh3dBqF
2. Predator 212cc Stage 1 with Dyno Results—In this video, the stock engine is tested again, making 8.4ft-lbs and 6.74hp during its best run. To improve the engine, a "stage 1" kit, consisting of a jet, air filter adaptor, and exhaust, was used. He compared it with and without a muffler, and the best results came from using a muffler, which probably influenced the tune of the carburetor to a more ideal air-fuel ratio. The engine made 9.03hp and 10.96ft-lbs.
Watch the video here: https://www.youtube.com/watch?v=tQjitfEMDxM&list=PLVZC6L6uyOvOqlFANuIb2NR6h-S3Gmevk
3. Predator 212cc Governor Removal Dyno Results – You'll need to use a billet flywheel to remove the governor and have the engine safely run higher rpms. The ARC flywheel increases ignition timing to 32°, which should help make more power, especially torque. You'll also need stiffer valve springs to prevent valve float. The video didn't use a billet rod, but we highly recommend one, especially for rpms above 6000. The Predator had less power, making only 8.9hp and 10.01ft-lbs. Part of the reason would be carburetor tuning and airflow. The Stock carburetors only have a main jet change because of the emission regulations. There isn't much you can do to improve the carburetor's air-fuel ratio. This video is importantbecause it shows even aftermarket performance parts don't guarantee better results.
Watch the video here: https://www.youtube.com/watch?v=vaL4-d5Fz70&list=PLVZC6L6uyOvOqlFANuIb2NR6h-S3Gmevk&index=2
4. Dyno Testing Carburetors – In this video, Carburetors are compared, but remember that a stock camshaft is still used. Here are the results from the different carburetors
Stock Jetted Carb(19mm) – 9.79ft-lbs/8.46hp
Genuine Mikuni VM22(22mm) – 11.6ft-lbs/10.53hp
Genuine Mikuni TM24(24mm)11.48ft-lbs/11.92hp
Clone Chikuni VM22(26mm) – 11.44ft-lbs/11.31hp
The engine is losing power in each video with the stock carburetor. The aftermarket carburetors make bigger gains because they flow more air, most importantly, and have a better tune. The real VM22 made the most torque probably because it had better signal/tune with the stock ports, but as the air demands went up, the knock-off VM22 and the real TM24 made more horsepower. With more tuning, the knock-off VM22 and read TM24 should be close to the real VM22 torque numbers. Red Beard has his best experience with flat slides as they are tuned better and run better.
Watch the video here: https://www.youtube.com/watch?v=wcLgy9t3q8Q&list=PLVZC6L6uyOvOqlFANuIb2NR6h-S3Gmevk&index=3
5. Predator 212cc Cam & Head Gasket Upgrade Dyno Test – The Predator 212 gets a Hot .265 cam with 26lb springs and a thinner head gasket to gain compression. A billet rod will be installed since the engine will be turning more rpms. The engine now makes 13.9hp and 12.37tq. One thing to point out is horsepower is now improving much more than torque. Horsepower is derived from torque x rpm /5252 =horsepower. Now that power is being made further above 5252, horsepower will improve. Another thing to point out is the steps Red Beard takes, starting with a better carburetor before adding a cam. The camshaft would make less of a difference if installed before a carburetor. As we explained in the video, when the billet flywheel was installed, it lost a little power because the carburetor wasn't tuned for the flywheel and was restricted by airflow. The camshaft would have helped, but not nearly as much as the carburetor. At this level, this build is very similar to our stage 3 kits, except the camshafts have different durations and centerlines, and our kits come with our WC22 vs the genuine Mikuni TM24. The non-ported Wildcat stage 3 made 13.48hp and 13.09ft-lbs, which was .42hp less but .72ft-lb more torque. The TM24 probably helps make just a little more power, whereas the 58mm crankshaft helps the Wildcat make more torque.
Watch the video here: https://www.youtube.com/watch?v=ywRx5GcMyXQ&list=PLVZC6L6uyOvOqlFANuIb2NR6h-S3Gmevk&index=4
6. Dyno testing 1.2 ratio rockers – In the video, 1.2 ratio rockers are added to increase peak lift to .318 minus the lash. Also, there are air filter adaptors and larger air filters. The engine made 14.43hp and 12.47 with the 1.2 ratio rockers. Again, torque only picked up .1ft-lbs, and power picked up .53hp. A gain in performance but not a significant one. The problem becomes air flow from the cylinder head. With our stage 3 kit on the Wildcat, we opted to port the head before upgrading the rockers or camshaft. We recommend that our customers do the same or upgrade the head as their next step. The Wildcat 223 made 15.48hp for a 1hp gain and 13.57ft-lb for a gain of .46ft-lbs. That means porting made twice the gains in horsepower and four times in torque than adding 1.2 ratio rockers. Another thing to look at is the Wildcat 223 makes more torque than the Predator 212, which makes horsepower at this level.
Watch the video here: https://www.youtube.com/watch?v=uDfxRmWmU28
7. Ported Head with Big Dyno Gains!!! - The Predator Hemi Head gets ported, and stainless steel valves are added. Unfortunately, we don't have any flow numbers on this head, but it goes to show that any amount of porting can result in good gains in horsepower. The engine made 16.35hp and 13.09ft-lbs, which is almost 2hp and .5ft-lbs more power. It now makes more horsepower than the Wildcat, even ported, but it has 20% more lift. However, the Wildcat still makes .46ft-lbs more torque. We're seeing the difference more stroke can make for torque, especially at low speeds, and where airflow helps for horsepower, especially at higher speeds.
Watch the video here: https://www.youtube.com/watch?v=TunNY-DNqtM&list=PLVZC6L6uyOvOqlFANuIb2NR6h-S3Gmevk&index=6
8. .308 Cam & Dual Valve Springs – A lot of work goes into adding a high lift cam like a .308. The spring pockets are cut for dual valve springs to control the valves. Chromoly push rods are cut to length and installed. With the 308 cam and 1.2 ratio rockers lift is .3696 minus lash. To keep the valves open longer, the .308 cam has almost 20 degrees more duration on the intake lobe and ten more on the exhaust than the hot 265 cam. The engine made 18.03hp and 13.58. The horsepower is about triple that of a stock engine, and the torque is now equal to that of the Wildcat 223 stage 3 with a ported head. We pointed the torque out to show how significant stroking the Predator 212 will be and where we expect to see improvements. It also shows the value of engines like the Wildcat 223 that already come with a 58mm stroke crankshaft. In the video, there was a small failure with the cylinder head. We said before that the Hemi heads were challenging to set up with dual valve springs because there was less material before breaking through the port ceiling and using a non-hemi style head was less of an issue.
Watch the video here: https://www.youtube.com/watch?v=9LSnUWMDumM&list=PLVZC6L6uyOvOqlFANuIb2NR6h-S3Gmevk&index=7
9. Predator 212cc to 223cc stroker kit – It's been a year or so since the last Road to Horsepower with the Predator 212 engine, and during the teardown, Red Beard noticed wear and fatigue on this engine. However, the goal is to stick with the engine as long as we can to show what improvements can be made. We have covered all the benefits of the stroker cranks and have done other tests that have shown they help make more torque. The Predator Hemi now makes 14.38ft-lbs and 18.18hp for a gain of .8ft-lbs and .15hp. The gains in torque are the best since the aftermarket carburetors were used. Since then, torque has improved but was not as significant. Horsepower was made about 900rpms sooner, so while it makes more at peak, the gains at 7000rpms are much higher. On the dyno graph, you'll see a dip in power. The engine is fatigued and could be losing the ring seal at that rpm since the piston speed is much higher. The rings and cylinder bore need to improve because there seems to be more power available for this combination without adding new parts. The next change would have to be larger valves. Ideally, with a non-hemi style head, this will require changes to the rocker's arms and push rods. To some extent, we have to go back a couple of steps to be able to go forward with this build, and that's why you need to plan for all of your builds.
Seeing the dyno numbers is only one part of the video, but seeing the engine in use shows the additional torque's significance and the powerband comes in sooner and later. The engine seems a lot like an electric motor. Lonnie is going to need a safer kart to really maximize this Predator 223 Hemi's potential.
