So the engine mount pattern is Honda CRF50.
There are many different Chinese engine manufacturers who make this style of engine - YX, Lifan, Jailing, Loncin, Daytona, Zongshen. American companies take them and rebrand them as GPX, G2, Thumpstar, OGM, SSR, Pitster Pro, Piranha and so on, but they are ALL made by YX, Lifan, Loncin, Jailing or Zongshen. And all of these engines are made in CHINA.
Honda, Takegawa, and Kitaco are top-of-the-line
engines made in Japan. Honda is a bit of both, all parts are engineered and manufactured in Japan but assembled in Thailand, Malaysia and China. These three options are ROCK SOLID
engines. They are very powerful, very expensive and very
reliable with proper maintenance and operation. If you have the paper, you can't go wrong with one of these.
Daytona is made by Zongshen and is a great motor, basically China's stab at the high-end engine market with a solid showing of power and reliability, but you pay for it, not as much as you would for the Japanese mills though.
Your best bet for getting a good balance of reliability, power, and affordability are Jailing, Lifan, Zongshen - in that order.
Now with that being said, if you buy ANY I repeat ANY
of these engines you will also need to purchase the 3-phase Stator/Flywheel from Fasttrails.com*
There are NO engines that come with a 3-phase stator except if you buy from Moto-scoot or Fasttrails Madass Engine kits. Even when an engine says it comes with a "lighting coil" it is still not enough for the Madass 3-phase system. A 3-phase charging system is characteristic of larger sport bikes.
Now, if you opt to buy the engine and stator separately you will save over $200 were you to buy the YX160 or Lifan 150 from FTP or Moto-scoot. You will need a $15 flywheel puller to do this swap though. Very easy to do.
One last thing, if you buy an engine with a "KLX-style head" thats fine, but the Madass exhaust will need to be bent accordingly to fit the angle of the exhaust port.
Planetminis.com is a the leading resource for these types of engines. Miniriders.com is the leading Aussie source.
* http://www.fasttrails.com/Item296/Madas ... elect.aspx