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Discussion Starter · #1 ·
I am often asked "why are custom valves so expensive" or "why is there some raw stainless showing on my custom valve"? it seems like i confuse guys more by trying to explain via text/email/phone. So i figured i would do a write up in hope to shine some light on it for some guys.


pick a valve material. if your in the market for custom valves your generally going to pick either stainless or titanium.

Stainless valve blank- $40.11
titanium valve blank- $170.00
*note* when using a titanium valve in order for it have good longevity the cast/powder seats need replaced w/ a suitable material for titanium. Example of such C630. it is possible to run titanium w/ a cast/powder seat but the valve ABSOLUTELY MUST BE COATED! if a raw titanium valve is meshed w/ a cast/powder seat it wont last a ride before it beats itself to death. also even with a coated titanium valve meshed w/ a cast/powdered seat it will only last until coating starts to wear off. once the coating has wore off it will RAPIDLY wear.


dimensions are needed in order to make the valve for that specific head. dimensions that are needed go as the following- Valve head diameter, stem diameter, overall length, margin width, seating angle and width (generally 45 or 46 degrees), and tulip angle.


you start with valve blank looks as such

A.) Valve head diameter is then ground to specified dimension- sorry no pic or video of this process
B.) seating face angle and width are established- also no pics or video of this process
C.) Margin is ground to the thickness desired- also no pics or video of this process
D.) tulip angle cut if angle desired is not available in a valve blank- also no pics or video of this process
E.) option machine work- 30 degree back cut, undercutting, cupping of valve head for lightening valve- also no pics or video of this process

a set of finished black diamonds. that has had steps A~E performed. The machining process of the list above removes the black diamond coating. With that said depending on what machining process need to be performed will determine where raw SS will show. in the case of this
valve the valve blank had the head OD desired as well as margin and tulip. that is why more of the black diamond coating is still retained. at this point i would like to take the time to explain the black diamond coating. it is a low friction coating applied to the valve to promote longer guide life. with that said its biggest function is to help aid with guide wear and machining valve head, tulip, valve face, and tip don't effect this.


alot of the aftermarket SS valves are of a EV8 or Inconel-751 stainless. well what does that mean? it means that stainless can not be heat treated to harden it. so what you say or what does that mean you say? if a lash cap is not present at the tip of the valve where tappet contacts it or hard weld. it will beat the snot out of the tip of the valve causing it to mushroom and deform. Same applies with titanium. so this leads into the next step. one of 2 things need to happen at the end of the valve. as stated above a lash cap can be used with SS or titanium. with stainless a hard weld can be applied to the tip.

Lash caps- for those who do not know what a lash cap is. its a hardened steel cap that goes on the end of the valve to protect from getting hammered by the tappet. i thought i had pics of this saved but i can't find them. i'll post pics tomorrow of how it works. cost of a lash cap is between $8~10. down side to a lash cap 5mm is the smallest that is mass produced (<--at least to my knowledge if someone know where i can get 4 and 4.5mm lash caps please tell :) ) and they are not moron proof.

stellite tipped (hard tipping)- is what i do with all my SS valves. downside to this the welding rod is hella expensive cheapest i have found it $50.00 a pound and a minum order of 10 pounds. which if i recall breaks down to about 4 or 5 buck per 0.100"/2.54mm of rod. plus it adds more machining time.

valve is first placed into a heat sink-this is so the valve stem dont see to much head and distort. then stellite rod is applied at the tip as seen in picture

B.) after weld is applied the valve then needs chucked into the lathe and dial indicated with +/- 0.0005"

C.) after getting valve indicated, weld has to be ground down.

D.) after grinding OD your left this
as you can see the end isn't true nor is the valve to length. so this leads to the next step grinding the tip til it true and overall length is met. the valve is then removed from the lathe and placed into the valve grinder and tip ground to length

E.) these valves i was doing tonight were for a custom big valve application. so known over length of valve wasn't known but valve protrusion was. so in this particular case valve protrustion was check


popping a keeper groove in valve.

A.) as with STEP 4 part B the valve is then placed back into the 4 jaw and dial indicted within =/- 0.0005"

B.) keeper groove location is then set and cut.

C.) after cutting keeper groove, groove and tip are deburred from machining process and tip is chamfered.



3,152 Posts
Discussion Starter · #4 ·
yes sir, I'm new in this forum, and I'm interested with your thread. I'm working on machine shop too. Actually I'm curious about the making of your custom valve. You know, in my country there's also mini bike, but actually it is a street bike engine. Same basic. I have a difficulties to finding a big valve, above 37mm with 5mm stem sir. I had plan to built TTR110 basic engine to 350cc engine.

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I assume you want stainless steel? If so call kibble white valves and order one of the above valve blanks
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