crankcase breathers? do they do anything?

okay so reading about them some say they add 5-10% power to 139 qmb engines

i kinda know how they work but has anyone actually used one?

there quiet cheap and for 10% power increase and abit of styling, its not too bad

thanks


here is a link to go have a look

1 -- https://www.pedparts.co.uk/product/1567/motoforce-racing-crankcase-breather--chinese-4-stroke

2 -- https://www.pedparts.co.uk/product/1938/naraku-racing-crankcase-breather-system--gy6-4-stroke

 

this is how they work......


Why do you need a crankcase breather? During the downward strokes of the piston inside the cylinder barrel pressure inside the crankcase can build up. This reduces performance, because the piston can no longer transfer its full force onto the crankshaft but also has to counteract the pressure in the crankcase.
If the overpressure is released, the engine will rev more freely and can put more power onto the road. Furthermore, the dangerous effect of oil foaming can be prevented to the greatest possible extent so that the danger of the oil film tearing off can be drastically reduced. The same negative effect also occurs during the piston's up-stroke, except that it's a negative pressure that builds up and also has to be relieved. The kit simply replaces the stock oil filler plug.

 

You already have a breather on the rocker box.