Hi Peter, Usually the only gain is approx 1 MPH on the top end if using the larger pipe, but loses a lot in the mid range [3000 to 5000 RPMs]. Have seen a few motors lose power on the top end with the insert removed. Not all inserts are created equal, and the good ones have the center pipe flush at each end.
From just what I have heard over the many years while riding on and repairing at times many small engines... 4-stroke baffle removal -- not a big deal -- more noise -- with that maybe as already mentioned -- more cops ----- where as to remove a 2-stroke baffle could toast the engine due to no back pressure.. Check your specks - back pressure may be required.. Happy riding from Mountainman
this works good for flow and noise ok cut the baffel down to only a inch and a half for start or more but fill it up with steal wool that you clean grills with and it makes it a lot silent on top of performance but its a trial and error till you get it right but it really works
Did you get the hi flow insert from me? If not you need to remove it and make sure the ends are "flush". If they are not, cut the perferated tube so that it is flush on both ends. If the tube is extended on the front side [towards the front of the bike],it will cause major turbulance and effect both power and gas mileage. I noticed several people have different concepts, but let me assure you I know about exhaust systems on the Whizzer motor. In fact the current insert is a close copy of an insert that Tom Hand [leading exhaust expert] and myself developed and tested approx 4 years ago. The insert was tested hundreds of times, and many of the times the tests were run on several different Dynos. Other than making the ends even, DO NOT make any other changes. If you drill extra holes, or remove the material the insert will perform much worse, I know this to be a fact. The untimate exhaust pipe on a Whizzer motor is 28 1/2" long [not counting the exhaust manifold in the measurement], the end of the pipe cut at a 45 degree angle [echo chamber cut off]. Just ask anyone that attended the dirt drags at Dawson Springs, Ky last month, how effective a tuned exhaust sytem can be.