Posted by Mark on 2/26/2020 to
Tech Reviews
EC Carburetors are the purveyors of performance and innovation. Working along with companies like Tillotson Racing, we are capable of building engines and components that raise the bar in small engine performance without draining your wallet. Our new 228R engine is the next step for our growing engine line up. This engine goes beyond the spec 225RS with more stroke expanding its capabilities and power potential.
We made a couple of improvements beyond the stock 225R, which comes as a long block and then made complete with add-ons. Technically, Tillotson does not make a complete 225R engines outside the 225RS, which has a different carburetor and ignition system and a spec muffler to complete the engine. The complete 225R and the 228R are engines made complete by Tillotson distributors.
In this article, I want to give some of the specs and answer common questions we get asked about the 225R and compare our improvements made in the 228R engine.
228R Specs:
Bore: 72mm
Stroke: 56mm
Total cc: 228cc(13.913ci) vs 225R/RS (223.93cc[13.665ci])
Compression Ratio: 9.22:1 vs 225R/RS 9.1:1
228R Includes:
• Tillotson 72mm Reinforced Block
• 27/25mm Tillotson Head
• 26lbs Valve Springs
• EC Billet Retainers
• Tillotson Racing Lightweight Hypereutectic Piston
• EC Billet Rod w/Babbitt Bearings
• 56mm Stroke Crankshaft
• SK200 REV V2 Billet Flywheel 34° Timing
• EC Tuned VM22
• EC Billet Intake Manifold
• Banzai 265 Race Cam
Your Choice of Red, Black, Blue or Yellow Recoil and Blower Housing
Add-ons:
• Plastic Hi-Volume Fuel Pump
• Chrome Recoil & Blower Housing
The exhaust header is not included.
72mm Tillotson Reinforced Block – EC Carburetors designed the Tillotson Reinforced Block intending to create new engine packages like the 225RS and 228R as well as other highly modified race engines. We made the block thicker and more robust to reduce flex and distortion; this prevents power loss through crank flex and blow-by between the piston and cylinder. I've written another detailed blog about the new Tillotson blocks; if you follow this link, it covers it in more detail.
Tillotson Racing Lightweight Hypereutectic Piston – I'm going to make a quick correction that is falsely advertised about this piston. The Tillotson 72mm piston is not a forged piston. Originally we wanted Tillotson to make this a forged piston, but to keep the costs down; they went with a hypereutectic casting. The piston uses the latest technology and design utilizing racing slipper skirt vs. conventional barrel skirt design of other stock pistons. This piston uses an aluminum alloy with high silicon for a lower coefficient of thermal expansion, allowing tighter tolerance for superior performance and longevity over stock Chinese cast pistons used in other engines and kits. The low slipper skirt design also allows more clearance in the rotating assembly for larger stroke crankshafts. In addition, we made the compression height shorter by moving the location of the pin and using a smaller diameter wrist pin. These improvements allowed the use of a longer rod while reducing weight in the rotating assembly.
We compare the Tillotson 72mm piston, pin, rings, and circlips to a 70mm predator/clone and 2.815"(71.50mm) Wiseco. Measuring the weight of each piston assembly, the Tillotson is the lightest at 166g while also being the largest in diameter. The Wiseco comes in 9 grams heavier at 175g, and the predator/clone comes in 31g heavier at 197g.
Comparing the wrist pins of each piston, the Tillotson is 40.24mm long, 13mm diameter, and wall thickness 2mm. The standard Wiseco pin is the closest in comparison at 47.75mm long, 12.5mm diameter, and 1.65mm wall thickness. The Tillotson is shorter to reduce weight but made in a larger diameter to increase the stiffness of the pin and wall thickness just a little thicker for added strength. The predator or clone wrist pin is much different at 54mm long, 18mm diameter and 2mm wall thickness.
Tillotson Racing Rings - Tillotson Rings are specifically designed for the Tillotson Racing Lightweight Hypereutectic Piston. We specify the ring tension to be better suited for racing applications. These rings reduce friction and increase cylinder sealing to improve mechanical efficiency compared to other stock piston ring sets.
EC Billet Rod – EC Carburetors designed the original billet rod for Tillotson 225RS engines, which uses a 55mm stroke crankshaft. Using what we have learned in the development, we made a more durable rod for RPMs above 6500rpms and higher output. This rod is made in house and is exclusive for our engine combination. Our new EC Billet Rods are designed to allow more stroke with standard clone journal crankshafts and bigger camshafts.
Looking at both rods, you can see they are very similar in design, but we made a couple of changes to the original. The Tillotson 225RS rod we designed is made much more reliable than any other stock rod and is made of billet rather than the predator and clone cast rods. The 225 rod is strong enough to endure 6500rpms for many races and potentially multiple seasons of racing in the spec class.
The new EC rod we made is a beefer version of that same rod. We added more width near the wrist pin, and you can see it bows in less from the middle to the top of the rod. The shoulders of the rods that the wrist pin goes through are also made slightly wider. What can't be seen in the pictures is the thickness of the center section of the rod at we made thicker on the EC. The last significant difference in both rods is the cut-away area of the rod made to clear the camshaft. We made this broader on the EC rod to handle larger camshafts.
Our goal is to make a rod more suited for modified versions of the 225 engine.
56mm Crankshaft – Our 228R is the first racing engine to come standard with a 56mm stock forged crankshaft. There is no replacement for displacement. We're giving you an additional 4cc. Standard 225 engine 72Mm bore x 55mm stroke = 223.93, EC 228R 72mm Bore x 56mm Stroke = 228. The added displacement helps make additional power across the board with a nice bump in the lower RPMs. By using the Tillotson Racing Lightweight Hypereutectic Piston, we have more than enough room for the additional stroke where other stock cast pistons do not.
.265 Banzai – EC Designed this cam for a broad torque band specifically for mini bikes and karts that need excellent low-end torque, whether it's accelerating from a dead stop or low-speed cornering. The cam would be duplicated for the 225RS engines as it was ideal for spec engine sprint racing. Peak power is around 7500, but with our 26lbs springs, we are capable of revving the engine over 9000rpms though this is not recommended for longevity.
Tillotson Racing Cylinder Head – Another EC designed component originally design to make the best performing head in the 196 box stock classes was then modified for the 212R and 225RS engines. We increased the stock 25/24mm valves to 27/25mm and went from 5.5mm stems to 5mm stems to increase flow. These modifications make the head well suited for the performance goals of our 228R engine.
EC Billet Aluminum Spring Retainers – While the stock 212R and 225RS heads come with automotive-style retainers and locks, we added performance by reducing the weight with a lightweight billet aluminum retainer. The retainer also adds a great look with its fire red hard anodizing.
Comparing the weight of each retainer, the stock non-hemi predator and Tillotson 212R and 225R retainers weigh 7g. The EC Billet Retainers weight only 2g. You may think this is not significant, but 1 gram on the valve side of the rocker is worth about 40rpms. That means the EC Billet Retainers are worth 200 extra RPMs. The 200rpm difference means more mph when using the same gear ratio just by changing the retainers. When you start adding all the advantages of the 228R, you'll see our attention to detail makes it a much faster engine.
EC VM22 Carburetor Kit – We have taken one of the most popular carburetors used on mini bikes and made it better. The Chikuni(Chinese Mikuni) carburetor is taken from the best castings by going direct with the carburetor manufacturer to get castings off the newest molds.
Even with the best castings, there is still work to machined and blueprinted these carburetors for the 212, 225, 228, and other similar engines. We calibrate our carburetors on the dyno using oxygen sensors, data acquisition, and decades of racing experience to blueprint our carburetors. Unlike the power sports warehouse distributors who only change the jets in these carburetors,
Jetting gets the carburetor better, but you can't get the same performance we have made by jetting alone. Since these are not original Mikuni carburetors, they lack the capabilities and parts to tune them properly. It takes fluent carburetor knowledge and machining skills to make this carburetor perform beyond its ability.
We chose to use knock-offs because the price point is crucial to our customers.
We also built our intake manifold to better fit on mini bikes or other chassis where space is limited. This intake also improves the signal to the carburetor and allows more airflow resulting in better performance. The EC Billet Intake is specifically designed around the Tillotson cylinder head and makes a near-perfect transition into the port. Compare the EC intake vs. the ones most power sports distributors buy from auction warehouses; you can see the difference in quality.
The best part of the 228R is you get all of these additional advantages at a lower price than any other 225 engine starting at $679.95 vs. 749.95 saving you $70. Your savings can undoubtedly pay for shipping and maybe a few additional parts.