Overview
I built a motorized bicycle out of a mountain bike frame and a 2-stroke engine kit, and it took a lot more revisions than I expected. I fixed fitment issues the kit's "universal fit" didn't actually solve, replaced a faulty CDI ignition module, tore down and rebuilt the engine after a blown head gasket and cracked piston, and eventually rebuilt the whole thing onto a new frame after the first one failed.
What I learned
- Assembled a 66cc 2-stroke engine kit (performance cylinder head, exhaust, carburetor) onto a mountain bike frame, diagnosing and correcting fitment issues the kit's so-called universal fit didn't actually solve
- Diagnosed and replaced a faulty CDI ignition module after initial bring-up failures
- Diagnosed a blown head gasket and cracked piston causing a compression failure, then fully tore down and rebuilt the engine
- Diagnosed a rich-running condition and intake air leak, then upgraded to an OKO 21mm carburetor and reed intake to fix idle and throttle response
- Full teardown and rebuild onto a new frame after the first engine failure
Project related blog posts
- Motorized Bike Review: My (Very Frustrating) Experience With 2-Stroke Kits From BikeBerry
- Resilience: A Motorized Bike Build
- Resilience - Starting the Engine
- Resilience: A Makeover