Shim-in-Tappet Spring Kit, 0.445" Lift, Yamaha®, Various 1049cc, 2003-2015

Yamaha® FX NYTRO™ 2008-2014
Yamaha® SRVIPER™ 2014-2015

Since 1939, KPMI® has taken great pride in our ability to design innovative performance improvements for valvetrains. This innovative ability has never been more apparent than with the development of the high tech lightweight racing valve spring kits for the incredibly stressed and torturous environment in today's high revving 4-stroke engines.
The challenge to engineer a valvetrain that would outperform OEM systems, that in some cases included titanium components, was not an easy one. This task would require the concentrated efforts of every member of KPMI®'s design team. It was apparent early on that an OEM style spring with a bit more pressure was not going to be the complete answer for these engines. Working together as a team enabled KPMI® to evolve with a "unified system" approach. In fact, these innovative high performance lightweight valve spring kits, would not only outperform factory parts, but outlive them as well.
Each KPMI® spring kit is designed for its specific application, taking into account several critical parameters including; cam profiles, harmonics, natural frequency of the springs, valvetrain mass, required pressure, wire stress, fatigue life, and engine rpm, just to name a few!
Today KPMI® proudly offers complete high performance lightweight valve spring kits for a host of applications.

KPMI® “Shim in Tappet” tappets solve the issues of retainer counter-bore ovaling and adjustment shims becoming dislodged. It is especially recommended for use with reduced base circle cams.