If you cannot find the valve you are looking for, call us and we will make custom valves to your specifications.  To request a custom valve, please provide us with one of the followings:

Our order form is available as an online form or in a printer friendly Acrobat version.  The form can then me mailed or faxed. 

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Pacifica, CA 94044  USA

  FREQUENTLY  ASKED  QUESTIONS

All of our stainless valves, whether White Diamond (chrome stem) or Black Diamond, are one-piece forgings made from a material known as EV8. This is a heavy-duty, high performance material that many companies will use only for exhaust valves because it is so expensive. They then will use a lesser grade of stainless material for the intake valves. We use the EV8 because we believe it is better to use the best possible material for the exhaust and the intake valves.

We also produce an Inconel exhaust valve (1 pc. forging) for the Harley, which should be used in engines running turbos, superchargers, nitrous oxide, or nitromethane. Tensilite valves are 1 pc. titanium forgings

Our Black Diamond valve is a valve that has undergone our proprietary multi-stage heat-treatment and surface finish process. This treatment actually reacts with the parent material to create a specific hardness to a depth of .002" while maintaining straightness. Once the desired hardness and surface finish are achieved, the valve undergoes a final treatment, which helps prevent galling. These processes, combined with the high-quality EV8 material have combined to create a valve that is strong and virtually impervious to stem wear.

All of the stainless valves that we produce for rocker actuated valve-train have a stellite tip and should not require lash caps. Titanium valves require some type of lash cap, as titanium is soft and will "mushroom" at the tip. Rocker arm condition should always be checked, as a worn or pitted rocker will cause damage even to a stellite tipped valve. Custom valves are also available with stellite.

In most cases, a builder going to oversize valves will also go to a cam with some more duration and lift. This combination of changes decreases valve to valve and valve to piston clearance. A shorter valve allows the builder to sink the valve to regain clearance without having too much stem protrusion, and subsequent loss of rocker geometry, and other problems associated with excessive valve stem protrusion.

All clearances are somewhat application specific and dependant on the state of tune, type of riding, and the condition of the engine. For instance you wouldn't run street clearances on your blown fuel Harley, and a bike that has vacuum leaks, ignition problems, is jetted wrong, or overheats will have seizure or accelerated wear problems. Generally speaking, one to one and one half thousandths (.001"-.0015") clearance on the intake, and two thousandths (.002") on the exhaust is considered safe.

The choice is a matter of personal preference based on several factors. The Alloy C630 bronze alloy is unlike any other bronze guide on the market today. This bronze alloy incorporates nickel for mechanical stability, hardness, and resistance to wear, and copper for its great ability to conduct heat. 25% of the heat of the valve is transferred from the stem to the guide, and then out to the head. It makes sense to have a valve guide that conducts heat well. These two alloys combined with the bronze alloy's natural resistance to seizing, and its ability to conduct heat, make this guide an excellent choice for performance engines. Many builders will run valve to guide clearances on the tight side when using these guides, taking advantage of the previously mentioned characteristics of this alloy to make sure the valve doesn't "wander around" in the guide. This insures that the valve strikes the seat squarely. These guides must be honed to size to insure a good surface finish.

There is nothing wrong with cast iron guides. Cast iron guides can be reamed to size, (although we recommend honing as it gives a better and more uniform finish) they wear reasonably well, and are less expensive than the Alloy C630. They have been used for years successfully in many applications. We have done a great deal of research to come up with the best cast iron possible for valve guides, and have had great results with them. Cast Iron does not conduct heat as well as Alloy C630, and may seize if run with tight clearances.

A hard alloy or cast iron seat in an aluminum head, should have seven thousandths (.007") interference fit. A nickel bronze seat in an aluminum head should have five thousandths (.005") interference fit, and a hard alloy or cast seat in a cast iron head should have 5 thousandths (.005") interference fit.

When I buy your stainless valves for my 4 stroke dirt bike do I have to run your valve spring kit?

Can I lap the KPMI stainless valves?

While lapping valves should never be equated with doing a good valve job,lightly lapping the KPMI valves with fine 280 grit or finer) lapping compound to make sure the contact surfaces are mating for a full 360° will not damage the KPMI valves. Too much lapping to try and correct a misalignment or out of round condition will wear the seat and the valve face out.

KPMI spent two years on research and testing of this unique material in high performance applications with titanium valves. The high copper content (80%) gives this material excellent thermal qualities, the nickel content at 5% gives it just enough hardness to keep from pounding out, and the aluminum content make it just soft enough to be gentle on the titanium valve face. In certain extreme situations some teams have even used it in conjunction with stainless valves to stop wear in their combinations.

Valves with a coating on the face should not be ground. The coating on  the impact zone is there to prevent rapid face recession. If you are using a titanium valve made from a blank with an uncoated face, then the valve may be ground.

One of the biggest contributors to the premature face recession of the OEM titanium valves is the factory valve seat material. KPMI urges anyone considering the use of any titanium valves to use our Alloy C630 seat material.

When KPMI components are designed for a given cylinder head, we look at the cam profiles and lifts available at the time of development. Typically we will shorten the top of the guide enough to allow for adequate seal to retainer clearance with those lifts. However, the builder should always check to make sure there is adequate room between the retainer and seal at full lift as other changes to the head or components can affect this clearance. We suggest .060” as a good safety margin.

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