Re: Suggestions on engine to get?
The deal with Dax and Neil's kits is that either they go thru each one and correct the flaws left behind from the factory or they most likely assemble them in house, but they also have a very good source where the engines are more carefully quality controlled... One thing I can say for sure is that there is a big difference in smoothness and reliability with their engines compared to the ebay kits.
My latest engine is a Dax bottom end with the top end I modified myself and it runs very smooth with really good powerfrom just off idle all the way up to max rpm. I could make it a lot stronger but there's always a trade off between low end torque and top end horsepower. The 9.5 Hp race engines are a bit slow off the line but very strong once reved out.
Now with the other engines I've mentioned like the 9Hp KTM clone sold on Dax's site, Yes it does make the power it claims to make, but it's a much higher quality engine with far better parts and closer tolerances so it does run very strong. There are a few members in here running that engine and they have nothing but good things to say about it.
Then the Morini and DeNardis engines, these are in a totally different class, they do make the 11hp they claim with the 50cc engine but these engines are also very high in quality and precision with only the best parts in the buildup. It's not uncommon for a 50cc 2 stroke to be able to make this kind of power but it's going to happen at 11000 rpm or more. I know Blata makes a 40cc engine that cranks out 14hp at nearly 15000 rpm and they put it in their brand of pocketbikes about 10 years ago, the Blata Origami can easily do 60mph with a 200lb rider... and this is a 40cc pocketbike. The other secret to these horsepower numbers in such small engines besides lots of RPM is the liquid cooling so they can get awaay with more power without as much engine destroying heat.
For the China Girl engines, their quality can be anywhere from dirt poor to excellent depending on who's selling them and if they take them apart and go thru them before selling them or if they just send you a box that hasn't been opened since it left China... To avoid this gamble, it's best to deal with reputable dealers like the ones mentioned in here and not just find the lowest price on ebay and go for it.
Hopefully this clears the air on the subject some...