YZ250 Carburetor Intake Manifold

For the same bike that got our Onyx & Kevlar upper motor mounts we did a replacement intake manifold. These old rubber intake boots have a bad habit of cracking leaking over time and they are often not readily available for older bikes. Our friend in Richmond called us looking for a solution. TPU is a material that is flexible like rubber when it prints so we though this was a viable approach.

Se started by 3D scanning the original part. We needed to do this because the carb inlet side is offset in the x, y, and z, dimensions from the engine mounting flange. We used this scanned image in CAD to draw a new part right on top of. This allowed us to pin down surfaces and angles very accurately.

Since TPU is soft, you cannot bolt into it and expect compression across the entire gasket face. To solve this we printed a retention plate from Markforged Onyx and packed is full of Kevlar for strength and resilience. The retention plate and the TPU boot mount holes have patching counterbore& raised area to ensure alignment and no walking of the parts.