FINAL: NKA OHV200 2014 Rules

Mike Burrell

New member
The "FINAL" NKA OHV200 class rules can be found here:
TrakBOOK

We sincerely appreciate everyone who provided us feedback and ideas on our "Beta" rules release on 10/31-11/22. Our goal was to "take out the grey", define the vague "OEM" term, and give manufacturers and engine builders a box to work within while keeping cost under control while hopefully improving quality and feasibility of the class for years to come…

Please feel free to call (317.774.7021) or email (tech@nkaonline.com) us with any questions!
 

astrowrench

Member
On This Sorry about the copy but don't you mean MAXIMUM????
15.11.1.1A
Valve Dimensions:

Intake valve OD
:
.980

minimum
.

Exhaust valve OD .937
” minimum
 

Mike Burrell

New member
Let me double check with our "4cycle gurus" Boyd and Tom. However, I if I remember right someone told me it was a minimum. I can't remember the exact reason why, maybe an engine builder can chime in and tell us why it would be a minimum instead of a maximum...
 

astrowrench

Member
Because Minimum is smaller.,................. you just made it illegal to run stock size valves might wanna get on that
 

Mike Burrell

New member
Here is the email explanation I received from our tech team member last night:

“A bigger valve will only flow more air if it has a bigger valve seat (oversize by tech. measurements). The bigger outside diameter of the head of the valve would impede flow (more surface area in which to pass over), but with a smaller diameter valve head in the same diameter seat (a known measurement) your air flow can be increased by air entering the flow-path quicker ~especially if the valve radius is worked and rounded correctly. Therefore a smaller valve diameter and larger radius is better.

In our rulebook for the 2013 year, we used: “Intake-OD .983” +/-.005” and Exhaust .946” +/-.005””. These are correct numbers. The oversize (maximum) numbers are not important as the minimum because a valve that is smaller will increase flow. Setting the low number at .980” intake minimum and .937” exhaust minimum was a result of working with a leading OHV200 importer and measuring numerous valves during the feedback period of our Beta rules.”

So, my understanding is the valve seats have a spec and when used with a bigger valve head it is counter-productive to air-flow; therefore, builders were grinding down or searching out valves with smaller heads to improve air-flow.

I grabbed three random stock valves out of the tech area at the office here, these were supplied by OHV200 importers for comparison purposes.
These are the measurements I got:
INTAKES: .983", .985", .983" (all legal under the .980" minimum rule)
EXHAUSTS: .944", .943", .943" (all legal under the .937" minimum rule).

They can be bigger than .980" and .937", respectively. They can be 4" if you want; just can't be smaller…
What measurements are you getting for the stock valves you said we just made illegal? Who is supplying them? What motor did they come out of? I'm happy to do what I can to help clarify your question/concerns!
 
Valves were summited to NKA from dealers and part suppliers. Out of all the valves, measurements were taken and a mean was determined as to our sizes used for teching the clone valve. Valve seat maximums (ID.) Valve and seat angles, were already determined and so was a min. weight for the valve. A bigger valve in a known seat size ...lets say a stock seat diameter, will add weight to the valve train, and if you move the margin of the contact surface of the valve face further up the seat increasing the likelihood the valve will not seal properly, and will impede flow around the seat and valve head outside radius. No flow advantage or improvement here. But if you take a smaller valve head... radius the head of the valve properly....change the angle of the valve face and seat an improvement is seen. The Minimum diameters given is to keep within the smallest valve head diameter known being imported and keep inventive engine builders within check......BM
 

astrowrench

Member
Gentlemen; As a long time builder I completely understood it. My problem is the kids and a percentage of the DIYers read it as being able to run bigger valves,as evidenced to me by calls & emails,for the past weeks; I want to Thank-You very much for stating Clearly what the rule is.....Now I can show them in Black and White without trying explain it to someone who does not understand.Again Thank-You and I hope we all have a safe Holiday season followed by a New Year of karting fun.
 

Joe Janowski

New member
Man....what a great team of people to work with. Mike, Boyd, Tom, and Jeff have all done a tremendous amount of work and have put hours of conversations with industry folks to develop this set. They've simply done an amazing job at balancing the current needs of the racers and the industry, but have also considered the longer term implications of the rules. Not only in clone, but in all of our classes. The job isn't done yet, but I can guarantee to all of you that they will get the job done. Great stuff.

I'm proud and honored to work with these guys. They truly make the NKA a great company to be involved with.

Joe Janowski
NKA, Inc.
 

mike00b

New member
Valves were summited to NKA from dealers and part suppliers. Out of all the valves, measurements were taken and a mean was determined as to our sizes used for teching the clone valve....BM

Why was the mean selected and not median or mode? What and how was the alpha level determined (point at which they were classified as illegal)? In other words, what percentage of 'stock parts from the factory' are we expecting to toss out? I know we're not looking for the 'scientific method', but if we were, the method in which data was collected is suspect. Not saying anyone submitted valves according to their preference that may have skewed the results or that valves measurements were tossed because they were outliers... Then again, if you want to run anyone's rules, its what they decide... no matter how it was decided...

When you're talking statistics, you've got my attention. It's what I do. Too often the basis in which stats are given have a very weak foundation.

Would love to know what the raw data was.
 
Last edited:
Mike oob
I guess my choice of words should have been more carefully chosen.You are right Median would have been a better word since ( Mean is an average or sum of) The Arithmetic Mean would have been the middle of the measurement and that is not what we were looking for. We were simply looking for the smallest and largest valve head dia. known to be in the clone engine. Maybe the word " Mode " or "Range" would have been a better choice. " Mode" seems to fit the bill the best ( number seen most often).
There will always be a possibility of making a wrong decision with parts changing from China on a daily basis, and a Type I error will always be present. If you want to be 95% confident that your analysis of valve dia. was correct you would have to have all the mfg's from china or importers of our engines being used in Clone racing to summit valves to be measured and that's not going to happen. We can't get karters to quit *****in long enough to agree on anything or even get all the sanctioning bodies to sit down an agree on anything to further the sport of Karting. (It's already been tried!) The best to hope for is to ask all the importers/dealers/ engine builders to summit parts to sanctioning bodies for anaylsis and go from there. I don't think they would send us parts that would be that much outside of the norm because they are in the business of longevity and that's not in their modus operandi .
The Alpha level will be controlled the best we can and this is a problem associated in every racing entity that writes rules. And since we don't have any Scientific types like you that will step up and help us with our trouble shooting were stuck with the every day tech. guy to figure it out ( No Insult intended) We are always looking for guys with a better understanding and education and I know NKA or any of the other sanctioning bodies would welcome you with open arms.The Raw data is not mine to share but I would discuss it with you by private message or telephone.Thank You for your input and lets continue the growth of our sport.....BM
 

mike00b

New member
I appreciate your response! I, too, am all for growing this sport. I will take you up on your offer to talk further... Thank you again.

Just to note: I'd never want to have all the sanctioning bodies to agree to one set of rules. Competition and differences of opinion is what drives innovation - I.E. the minimum (not maximum) valve rule.

Sending a PM now.
 

Joe Janowski

New member
For a little fun, and just to see if anyone is paying any attention, it's time for a give away.

The first person to post in this thread the NKA mailing address and phone number gets a $50 gift card. No strings attached.
 

JamesClarke

New member
po BoX 2166
Noblesville, in 46061
317-774-7022


For a little fun, and just to see if anyone is paying any attention, it's time for a give away.

The first person to post in this thread the NKA mailing address and phone number gets a $50 gift card. No strings attached.
 

Joe Janowski

New member
Nice James! That was fast. I was sure that was going to sit there for a week!

PM me your address and I'll get it on its way. Merry Xmas!
 

JamesClarke

New member
To much snow to go out and do anything and waiting on april to come. So only thing i can do and not get cold is stay up to date on here. lol

Merry Christmas
 

Renegade

Member
On the valves I see one small problem. In five years and over 2500 clones we have worked on, I have never seen an exhaust valve smaller than .937" so that's good. I have however seen intake valves at .978" many times before and I am sure we will again. I do like that you took the +/- .005 off the valves and went with a minimum.
 

Mike Burrell

New member
Renegade:

We're looking into your concern; I'm sure there are valves out there under any rule we would set… Of the 50 or so intake valves we measured, two at .980 were the smallest and the average was just over .983. We don't want to get anyone bounced; however, we're also going to have to draw the line somewhere so the manufacturers can themselves in line. The goal is long-term stability: not to change the rules every week!
Thanks for the post and insights!
 

sCREamnClones

New member
Renegade:

We're looking into your concern; I'm sure there are valves out there under any rule we would set… Of the 50 or so intake valves we measured, two at .980 were the smallest and the average was just over .983. We don't want to get anyone bounced; however, we're also going to have to draw the line somewhere so the manufacturers can themselves in line. The goal is long-term stability: not to change the rules every week!
Thanks for the post and insights!
"Final Answer".....(unless otherwise specified, or....Common Sense Prevails)....both acceptable :)
 

Renegade

Member
Not saying you need to change it. All the current crop of valves out there are good to go. That is the current crop, just be aware there have been smaller before and I am sure at some time in the future there will be more. So racers, you need to check your engines.
 

PD Power

New member
Tempest in a teapot.
Stop this by making a max and a min size of valves.
Also legislate min. max angles on seat and valve. KISS.
 
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