No its not, and all the posts recently about noobs trying to use it on nearly stock motors and having nothing but problems supports that. It has already been proven that 21mm is too much for stock bore chinagirl, it is far from a "great carb" for us. Big carbs are 4-5 year old fads that no fast bike uses anymore. A too big carb will not HURT power, that's not what I mean when I say "too big". Your peak will be the same, but low end and throttle response will suffer. Simple physics - same amount of air moving through a larger carb orifice means less velocity, decreased fuel atomization, rougher idle, harder to tune, worse throttle response, and irregular fuel delivery. I don't care about a video of a slow bike in the woods, even though it did prove my point with the poor throttle response and lazy low end(not sure what you thought that vid would show). Maybe it would be a good match if it was a sleeved 50mm bore on meth or a ported minarelli top end making 9+hp but it clearly isnt. I have ran 5-6 different carbs of all sizes on my same test bench 47mm chinagirl motor and the best one was the PHBG 19mm. Overall performance was better than anything else from stock all the way up to 24mm. Also have 26mm and 28mm carbs, but they are for my 4stroke and WAY overkill so were not tested.
To clarify again though, my chinagirl is a piston port motor. Of my 3 personal bikes I currently have, only my BMX build uses a reed (49cc moped motor with 45mm top end). Also none of my bikes are from Rob and I am not affiliated with them in any way - the chinagirl was purchased through him but it was because he was selling stock unassembled kits direct from Zehe at nearly bulk invoice prices and I got like 8 kits from him at the same time back when I was selling bikes. I build my own engines. Since you brought him up though, he USED to use and recommend big carbs on his motors 2-3 years ago, but now even his 10+hp motors all use 21mm carbs. Only the race motors on meth require larger. Hell, my BMX build I mentioned above does 65mph and spins over 10k RPM with only a 19mm and 4 pedal reed with super crisp throttle response and amazing mid range. It hits the pipe harder than an over the hill rock star whose band just broke up
. No way your weaker, slower, lower RPM motor needs a much bigger 24mm carb than that does.
Swap to a VM18 and I bet your bike is faster everywhere in the RPM range. Your 5-6hp chinagirl doesn't need a bigger carb than an 11hp KTM lol.
