It's now here, due to popular demand! ESP Now does both the modification AND porting work on these kits!
If useable power is what you crave, look no further. This ESP modified big-bore combo kit will allow you to convert your current 4-bolt engine into a 30.5cc performance monster. Feel the power that only a larger engine can provide. This kit is an amazingly balanced engine, with tons of low end power, yet it remains very high-revving. ESP modifies this top-quality Zenoah 36mm 4-bolt cylinder by machining at the head. These ESP modified cylinders are then championship race ported by ESP - intake, exhaust, and transfer ports have been enlarged/reshaped for more fuel/air flow and hence more power. The 36mm Zenoah cylinder is the largest RC-style bore made by Zenoah, and has the advantage of Zenoah's superior casting and plating. However, the stock 36mm cylinder does not have room for the longer crankshaft (30mm stroke compared to the stock 28mm stroke, for a +2mm longer stroke) in this kit, so ESP has machined out the proper spacing. This is a more efficient and reliable solution than stacking gaskets to achieve the needed space, as there is proper spark plug clearance and the piston ring remains in the well-plated area of the cylinder. The squish band is cut so there will be .020"-.025" of squish (using the stock .020" cylinder gasket), and the combustion chamber is machined to get the compression ratio down to 14:1 for running on premium pump 91 or higher octane gasoline. The head geometry, however, is reshaped to the proven standard 'hemisphere' shaped combustion chamber, and the squish area equals 50% bore area, for more effiecient burning. Kit includes ESP modified Zenoah 36mm cylinder, 36mm piston, piston ring, piston pin, circlips, base gasket, spark plug, and option to add a 30mm stroke crankshaft. Note: this kit must be used with a 30mm crankshaft. The option of "No Crank" is offered below only for people who already have the proper crankshaft. Increases your engine displacement to 30.5cc (36mm bore, 30mm stroke). Increases engine power SUBSTANTIALLY - estimated engine power output is 4.3+ HP. This high-performance product requires 91 octane (using the R+M/2 octane rating method) or higher fuel, and comes without warranty.
Fits 4-Bolt Crankcases (G240RC/G270RC Only.) This 4-bolt cylinder is NOT compatible with 2-bolt engines or cases!
Doug @ ESP has just submitted his description for this kit:
ESP ported 36mm bore G290 top end kits
THEY'RE HERE! The new Zen G290, 36mm bore 4-bolt cylinders are the most reliable 36mm bore that we can now use, and ESP was eager to add their Championship winning porting and head work (for the 2mm cranks).
“We (the hobby industry) asked Husky/Zen for a 36mm top end, they saw the need and came through, but they surprised us by making them 4-bolts. Now we can work on making even more power, without the worry of breaking a cylinder off or the possibility of a premature plating failure (so you know your money won‘t just--flake away). I think you can expect a lot of fast engines being made from this top end” (Doug @ ESP)
The 4-bolt cylinders (G270/G290) right now have enough squish clearance to install a 1mm stroke crank with no head nods or cylinder gasket stacking (use the stock gasket), but that can change in the future, because the 2-bolt Zen G260 used to be the same way (now have tighter squish stock).
Here is the crank configuration ESP recommends with their ported and head modified 4-bolt head kits.
G270/G290-- No head mods (ESP ported, but squish band and combustion chamber left stock). Use either stock stroke crank, or 1mm stroke crank with no other changes. 1mm crank gives a noticeable mid range gain, but may lose a few hundred RPM (typically).
G270 (27.2cc)/G290(30.5cc)--ESP ported, and has head mods performed (squish and combustion chamber cut to accept 2mm crank). This is choice for the 30.5cc engine. More “hole shot” or “corner to corner” low and mid range than the 1mm and stock crank, but typically, the 2mm cranks are not known for making screaming piston port engines, but usually have enough power to gear high, if top speed is what your looking for.
The Championship winning porting is the same high quality you have come to trust and expect from ESP, and the amount of detailed work done on each top end kit is not reflected in the low price. All porting is now done with a CNC mill with excellent port time area repeatability, and then finished and detailed by hand to perfection, just like what is done for all of ESP’s sponsored racers.
ESP guarantees their workmanship to be defect free, and as reliable as a stock Zen RC engine. If a failure is the fault of ESP workmanship, all damaged parts will be promptly replaced for free. Feel free to call Doug directly at ESP for any questions or possible trouble shooting after the sale. Doug @ ESP is happy to help get you running ASAP.
