Dick Its not about superior carbs. Walbro makes carbs for all the engines we use, as you know they are quality. The problem is the mfgrs. are not taking the time to check with Walbro to see if the carb they have selected is calibrated for the cc engine they are selling. I am refering primarily to the 100 to 210 cc engines. The mfgrs. are supplying a carb that is calibrated for a 100cc engine on 150-200cc engines. this is a fact, and anyone can get the same info from Walbro. The problem with a carb that is too small is this: One cannot get the engine to run rich at wide open throttle. Have fought this problem for years, with a 150cc engine with a Walbro wga-7, which in stock form is in fact calibrated for a 100cc engine. Now my question is : Why is it so hard for the engine experts to do a little research and install the right carb???Why is it so important to be able to richen the mixture at w.o.t.? the only way you can be certain that your mixture is not too lean, is to have this reference point when tuning your carb, and I think this would be very important to folks using 100-1 oil mix. the correct carb for 150cc engines is the Walbro wb-25, this may be ok for a 170cc engine too, the 200 cc engines should be ok with a walbro wb 45, of course this is just an opinion abiout the 170-200cc engines. The wb-25 is in fact the correct carb. for the 150cc engines