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Blat, Blat, Blat
Mini Chopper Custom Exhaust and Engines
For our smaller mini chopper project, we elected to use a 3 HP Briggs and Stratton engine. This produced plenty of power for a 200 pound rider and the bike.
To get even more power and response, a torque converter may be used to achieve a variable speed transmission.
The Engine
We used a 3 hp Briggs and Stratton engine for the small mini chopper. This is a horizontal shaft engine, found on tillers, go karts, and the like.
[Read more about engine choices].
The Exhaust
You may certainly use a standard engine exhaust for your project. This will accomplish the quietest ride, and the high-flow mufflers that are made shouldn't effect your performance in any large way.
However, if you've already purchased a pipe bender, we strongly suggest making your own custom exhaust.
All horizontal mount engines are generally threaded with NPT pipe threads on the block. Our 3 hp engine accepts a 1/2" NPT thread.
Open Pipes Custom Exhaust
Black pipe was purchased at the local Home Depot. After measurements were made, the 1/2" pipe was bent at roughly a 60* angle.
This bend was measured, and the next bend was selected. An opposite bend was made in the opposing direction finished our exhaust pipe, which fit the profile of the frame very well.
Installing the Custom Exhaust
The engine was removed to install the exhaust, since it had to be screwed into the block. The result was phenomenal. The open pipe completely changed the tone of the engine. Rather than the predictable "lawnmower" sound, a deeper, satisfying "blat, blat blat" emanates from the pipes.