These big-bore kits have been ESP Championship ported - intake, exhaust, and transfer ports have been enlarged/reshaped for more fuel/air flow and hence more power.
This is the "high rev" version of the kit - designed for maximum RPMs. Not recommended for Tight RC tracks and areas, Scooters or Helicopters - for those applications, get the "High Torque" version of this top end, seen in the related items at the bottom of this page.
This is the long-anticipated 4-bolt Zenoah 36mm 29cc bigbore kit! This kit will fit Zenoah G240RC/G270RC engines, or any engine running the 4-bolt Zenoah cases. This includes the parts shown (piston, cylinder, ring, spark plug, base gasket, c-clips, pin)
This 36mm cylinder is for use with the standard 28mm crankshaft. We will also be offering modified kits to accomodate the +2mm stroker cranks.
This is a championship ported version of Zenoah part # 966508401
Doug @ ESP has submitted his description for this item:
Introducing the new “High Rev” ESP 29.5cc top end kits.
(Written by Doug @ ESP)
This High Rev kit is for racing applications only!
This kit (with the Quick Draw hot pipe), peaks about 6.75hp at about 16,000 rpm and revs up to 21,000rpm on the ESP dyno. This kit, (tested with the Quick Draw pipe) is the highest reving piston port top end kit for air cooled engines that ESP has offered to date. Different pipes will yield different results in performance. This kit is significantly lower in power in the lower RPM range, and may not be the best for your application. It was made for people who have the room to let a engine scream, and it may need a higher RPM clutch spring or adjustable clutch (better yet) to engage where the engine makes good power. Not recommended for Tight RC tracks and area’s, Scooters or Helicopters.
As always with ESP, you can expect top performance (with a good set up and proper carb tuning), quality control that is almost impossible to beat, with attention to detail that is unmatched in the industry. All that, with a price others can not match (considering the work done) and friendly, informational, telephone customer service that is a stand out above the industry standard. I don’t outsource my CNC work, and do every bit of the work myself, from the “tear down“ for complete engines, to the CNC machining, (where every spec is repeated, part after part and batch after batch), to the hand work for finishing, and also improving Zenoah‘s quality, to the clean up and reassembly (if a complete engine),--so I can guarantee you ESP builds quality cylinders and engines every time.
I highly recommend using the Zenoah G240/G270/G290 sealed 3rd crank bearing, (Replaces your large diameter crank seal, if your not using the 3rd bearing now), and the Zenoah 1mm crank, for the best crank stability with these engines (not sold with the kit).
This top end also works with +1mm stroker cranks with no additional modifications.