Hot Rods Bottom End Kit for Yamaha YZ 125, 2005–2016

Quick overview

If you’re planning a full engine rebuild, a kit that groups the crankshaft, bearings, seals, and gaskets can be more convenient than sourcing those parts separately. This Hot Rods bottom end kit is listed for the Yamaha YZ 125 from 2005 through 2016 and is described as vehicle-specific.

It includes a fully assembled, factory-trued crankshaft, a main bearing and seal kit, and gaskets and seals for the top and bottom end.

That makes it a broad parts package for a rebuild, rather than a crankshaft-only replacement. The listing also says OE replacement and displacement-increasing stroker versions are available, but it doesn’t identify which version is selected here. Keep that detail in mind before choosing a kit for a particular build.

How to use it

This kit is intended for an engine rebuild, with parts covering both the crankshaft area and the top end. In practical terms, it could suit a project where the engine is apart and you want the main rotating assembly, bearings, seals, and gasket set together. The assembled crankshaft is factory trued, according to the product information, installation and any additional work still depend on the condition of the engine and the needs of the repair.

It suits you if you’re already planning to replace several of these components at once. It might not be a great match if you only need a single gasket or seal, since the package includes a wider set of parts. No maintenance schedule or installation instructions are provided in the supplied details.

Practical tips

Before ordering, match the listed Yamaha YZ 125 year range to your bike and confirm whether the kit you’re selecting is the OE replacement or stroker version. Those are different approaches: an OE replacement is aimed at replacing the original-style assembly, while a stroker version is described as increasing displacement. The available information doesn’t say which configuration this particular listing contains, so don’t assume they’re interchangeable for your build.

When preparing the job, lay out the crankshaft, main bearings, seals, and gasket components and compare them with what the repair requires. A rider dealing with an engine already disassembled may value having the top- and bottom-end gasket and seal kit in the same package, someone doing a narrower repair may be better served by buying only the needed part. The listing provides no extra fitment details beyond the stated vehicle-specific application.

Practical doubts

Which bike does this kit fit? The product name specifies a Yamaha YZ 125 from 2005–2016. The listing describes fitment as vehicle-specific, so the application should be matched to the bike rather than treated as universal.

What parts are included? The stated contents are an assembled, factory-trued Hot Rods crankshaft, a main bearing and seal kit, and a complete top- and bottom-end gasket and seal kit.

Is this the OE or stroker version? The description says both types are available, but doesn’t clarify which version this specific selection represents. Confirm the configuration before buying if that distinction matters to your rebuild.

When it makes sense

This kit makes the most sense when you’re rebuilding a compatible YZ 125 and want the listed crankshaft, main bearings, seals, and gasket components in one package. It’s less compelling for a small, isolated repair, or when your build depends on a specific stroker configuration that the listing hasn’t identified. The key buying decision is not just whether the year range matches, it’s whether the kit’s version matches the engine work you intend to do.