Has anyone ran a c model motor in a A model bike? Does the different cdi present a problem or do they run fine
Morning Oaks. ZXR250C "C" engine in a ZXR250A "A" frame is a bit like a heart transplant but you need to take the lungs and nervous system too. The C engine has the same pickups as the A engine so there are no different connectors to worry about the bike running if you're an electrical expert and want to graft a C engine into an A bike. There are wiring diagrams in the RESOURCES section of this forum website. The C engine/carbs/TCI are configured to work with the C engine's different Bore and Stroke, so there are a few issues to address even if you are an electrical expert. Otherwise, if electrical problems make you curl up on the floor in the foetal position (like me), then you will need to take a complete C loom (with TCI and fuse box) with the engine when you perform the transplant. You will also run into issues with the RHS switch-block and headlights as the C model handles the start-up sequence a little differently to the A model. The carbs are the same, but they run different main jets because of the different borexstroke and also because the C TCI unit has a slightly different spark advance curve to that of the A model TCI. The C carbs run through an interesting piece of plumbing to control vacuum at different rev ranges, so their inlet boots have a slightly different vacuum hose configuration. You don't need any of this, so stick with your A model carb boots and hose setup. You can plug a C TCI into an A model loom, but the bike won't run as the Pickup signals go to different plug points, so NO SPARK (no go). Hopefully, this Readers Digest version of the "C into A" process has been of some help for you to decide your next step. Cheers P.S. Out of curiosity, what's wrong with your A engine?