this might be irrelevant to some ... However I must say that I am pretty dam impressed with the B5 engine.. As you know I like to modify engines, therefore there are certain mechanical attributes I look for in a engine to begin with and the B5 definitely delivers...
The B5 carburetor is fantastic, it is nicely machined, well insulated, the o-rings are doubled up and are quite tight in the barrels...Not only do they fit well, bur Werk's also uses 2 different o-ring compounds on the needles...It is one of the best sealed carbs I have come across.....What this translates into is that the engine holds a stable tune no matter how hard it is pushed...
The B5 has a very beefy case, the case is heavy and robust, not only does it offer great support, it also offers good thermal stability....Some of the cheaper Taiwanese engines ( not implicating Alpha ) have cases that are very thin and lightweight, which can result in rapid changes in the engines core temperature...which in turn results in swings in the engines tune....If an engine sheds heat too quickly it can become difficult to maintain a stable tune.... same reason the magnesium head offroad engines were trickier to tune.... The B5 is very very beefy, just picking it up you can feel that is a fair bit heavier then its Taiwanese competitors....As as modified I can push the B5 quite far and its able to maintain a stable tune better then almost any other engine I have tested....
stock the B5 is very potent, it has awesome torque...i mean seriously this engine has some balls..more torque then even a Picco 21...However it still manages to trigger very smoothly and get good runtimes....The B5 does carry a good top end as well, its not the highest revving .21 i have run, however it does have a very good overall powerband, its top end is actually quite good, especially when you consider how strong its low end is....
As a modified the B5 is extremely stable and easy to tune, it has buttery smooth power delivery and great trigger modulation... It makes outrageous torque and RPM and still manages to get 10 minute runtime on the 2057...
Personally I think its one hell of a nice engine for $200.00, especially when you consider how robust the engine is built.....
I am not knocking the Alpha, as it is highly praised and obviously a great engine..However I only have first hand experience with the Werk's so that is all I can really comment on at this time.... But for whats it worth I give the Werk's two thumbs up !