It sure sounds like you got the Zenoah G2D Engine.
I would recommend that you get a new SiKK 27cc or 29cc engine from
http://www.davesmotors.com
Or look at the 27cc Carson Engine from Hobbythek
http://www.rc-car-online.de
Both the Carson and the SiKK are actually CY engines, and they are clones of the Zenoah G260.
You will need new engine mounts as the G2D and the G230/G260 has different mounts.
Since you are inside the EU, it might be easier and cheaper to go the Hobbythek Way, but if you chooses one of the many US shops that cary SiKK, then ask them to ship using USPS, it is often slower but shipping cost is a lot cheaper than FedEx or UPS.
Daves Discount Motors ships using USPS, and they have given me excellent service, but Ok. being in Greenland I am outside the EU VAT(Moms) and Import Tax hassle...