2007 cr250 build

kyle-vick
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kyle-vick 10/2/2020 5:20pm
10/2/2020 5:20pm
Well 4140 sure works great for axel shafts. That stuff is strong. We make all of our rubber injection mold cavities from it. I am not aware of the conditions or torsional loads this part will be under, but I am sure if someone wants one made, we could make it out of whatever they would like. I could check with our heat treatment company to see what they can do, they more than likely can do induction case hardening. We usually heat treat D2 to 48-52 RC so it is not too brittle.
matt.3150
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matt.3150 10/3/2020 11:20am
10/3/2020 11:20am
kyle-vick wrote:
Well 4140 sure works great for axel shafts. That stuff is strong. We make all of our rubber injection mold cavities from it. I am not...
Well 4140 sure works great for axel shafts. That stuff is strong. We make all of our rubber injection mold cavities from it. I am not aware of the conditions or torsional loads this part will be under, but I am sure if someone wants one made, we could make it out of whatever they would like. I could check with our heat treatment company to see what they can do, they more than likely can do induction case hardening. We usually heat treat D2 to 48-52 RC so it is not too brittle.
For what the shaft is doing it really doesn’t make that much differents, just about anything will work. My thought was 4140 and case hardened because that what most transmission shafts are. You could use Ti , you could use stainless. There really aren’t any real wear surfaces or stress sections. Tool steel would be just fine, it would last along time, just actual might be over kill.
FU2
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FU2 10/3/2020 12:17pm
10/3/2020 12:17pm
timobijnen84 wrote:
If someone knows the angle between the 2 planes of the sqaure parts I could make a cad drawing which should make it easier for youre...
If someone knows the angle between the 2 planes of the sqaure parts I could make a cad drawing which should make it easier for youre machine shop to fab one up.
I have two of them , one new. Have the bike apart. If the guys here need a drawing and you're willing to do that then i can let you borrow a shaft. Als het maar terug komt.




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kx450sr
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kx450sr 10/3/2020 1:29pm
10/3/2020 1:29pm
FU2 wrote:
I have two of them , one new. Have the bike apart. If the guys here need a drawing and you're willing to do that then...
I have two of them , one new. Have the bike apart. If the guys here need a drawing and you're willing to do that then i can let you borrow a shaft. Als het maar terug komt.




Whoa that's awesome thank you! Whoever can fab some up I'm sure will have an abundance of takers as NO ONE has these. I'd buy one just to have as a spare for sure

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FU2
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FU2 10/3/2020 11:29pm
10/3/2020 11:29pm
kx450sr wrote:
Whoa that's awesome thank you! Whoever can fab some up I'm sure will have an abundance of takers as NO ONE has these. I'd buy one...
Whoa that's awesome thank you! Whoever can fab some up I'm sure will have an abundance of takers as NO ONE has these. I'd buy one just to have as a spare for sure
I an ask a guy here who is in auto racing and makes TI parts for race cars. I can ask around what it would cost to make it and i can ask what it would cost to make one out of steel. It's quit heavy and hard for such a little part to be honest.

I'm using TI pins in the TI footpegs. The wear what it has after 30 hours is not that much what i thought it should be. So can Ti be the right choice or must it be steel? Best thing would be a drawing so more people can ask around.

I have no clue on this what to use for this part. But asking is free so far i know.
FU2
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FU2 10/5/2020 4:44am
10/5/2020 4:44am
Well coz i don't need one but did ask around what the options are.

It can be made but not titanium, that's not gonna work.

So i can give my shaft to a local guy to see what it will cost to duplicate one or more.

That's about it what i can do.

Maybe smart to get a new valve flap to from Honda, you will see the difference between a new one and a used on. Before they are gone to.



TheTwostrokeTaliban 10/5/2020 5:14am
10/5/2020 5:14am Edited Date/Time 10/5/2020 5:14am
You need to:

Make a few blanks from the same 4140 billet.
Rough machine it
Heat treat
Finish machine.
Test Rockwell hardness on blanks

Youre looking for 60 to 62 Rockwell C on your finished part. Oven treating it will heat treat it 2 or 3 mm deep in theory, leaving enough treated surface after you finish machine it.

If it were me, I'd buy a complete cylinder and sell the incomplete one. It will be easier and cheaper than making that part. I make a lot of my.own stuff, but I've learned to "choose my battles"
kyle-vick
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kyle-vick 10/5/2020 5:31am
10/5/2020 5:31am
TheTwostrokeTaliban wrote:
You need to: Make a few blanks from the same 4140 billet. Rough machine it Heat treat Finish machine. Test Rockwell hardness on blanks Youre looking...
You need to:

Make a few blanks from the same 4140 billet.
Rough machine it
Heat treat
Finish machine.
Test Rockwell hardness on blanks

Youre looking for 60 to 62 Rockwell C on your finished part. Oven treating it will heat treat it 2 or 3 mm deep in theory, leaving enough treated surface after you finish machine it.

If it were me, I'd buy a complete cylinder and sell the incomplete one. It will be easier and cheaper than making that part. I make a lot of my.own stuff, but I've learned to "choose my battles"
Will 4140 even get that hard? All of the charts I have seen say it typically only ranges from 54-59 HRC fully hard and that's not tempered.

I completely agree with your sentiment on choosing your own battles. I make a lot of stuff too and have came to the same conclusion. If I can buy it, I would rather. That way I have more time to actually work on the stuff I want to work on instead of making stuff just so I can work on it.

With that being said, I do work at a machine shop, and we can more than likely make these. So if it is just simply impossible to purchase this item, hit me up and we can try to come up with something.
TheTwostrokeTaliban 10/5/2020 10:18am
10/5/2020 10:18am
Good question on whether or not.you can achieve that hardness. I'm alnost positive you can but I dont have a degree in metallurgy so I don't want to eject ass-facts.

Another question is, will 57-59 be hard enough for thst part, and the more I think about it, yes, it probably is.

Since you're a machinist, what do you think about rough machining it, then Ti nitride it pretty thick, then finish machine into the nitride? I know thats a thing, just not sure if its the best route here. It might be.

Now with all this being said, the Honda power valve is just a damn flap guillotine that impedes exhaust flow. It doesn't work very well to begin with like the yamaha ones that seal up when they're closed.
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mxracer666
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mxracer666 10/5/2020 12:11pm
10/5/2020 12:11pm
Hey TTsT: It doesn't matter how great the Yamaha one works, we are talking about Honda's here! LOL! Seriously tho - If someone reputable can make these , and make them correctly (!), while having the flap and bearings to check final fitment, this could be a big selling item, worldwide. They are NLA from Honda.
timobijnen84 12/18/2020 5:16am
12/18/2020 5:16am
FU2 wrote:
Well coz i don't need one but did ask around what the options are. It can be made but not titanium, that's not gonna work. So...
Well coz i don't need one but did ask around what the options are.

It can be made but not titanium, that's not gonna work.

So i can give my shaft to a local guy to see what it will cost to duplicate one or more.

That's about it what i can do.

Maybe smart to get a new valve flap to from Honda, you will see the difference between a new one and a used on. Before they are gone to.



Did you get around to doing this. And do you have a price.
I would be able to take all the measurements and make a model and manufacture them. I can get all the materials that would work. I dont know what hardening would cost.
Maveric_Stant 3/17/2022 7:41am
3/17/2022 7:41am
finally someone could get the exhaust shafth of the cr 250 2007 I need one. (14211-KSK-730).[/b]
Maveric_Stant 3/18/2022 4:26am
3/18/2022 4:26am
Last2Stroke wrote:
Replicas available on eBay... https://www.ebay.com/itm/265371735339 [img]https://p.vitalmx.com/photos/forums/2022/03/17/538631/s1200_11.jpg[/img]
Replicas available on eBay...
https://www.ebay.com/itm/265371735339

Thank you out of ordering one I needed it rush..thank you very much.
Last2Stroke 3/18/2022 4:05pm
3/18/2022 4:05pm
Last2Stroke wrote:
Replicas available on eBay... https://www.ebay.com/itm/265371735339 [img]https://p.vitalmx.com/photos/forums/2022/03/17/538631/s1200_11.jpg[/img]
Replicas available on eBay...
https://www.ebay.com/itm/265371735339

Maveric_Stant wrote:
Thank you out of ordering one I needed it rush..thank you very much.
Shipped, let me know if you have issues with it.
Salem
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Salem 10/11/2025 9:10pm
10/11/2025 9:10pm
Last2Stroke wrote:
Replicas available on eBay... https://www.ebay.com/itm/265371735339 [img]https://p.vitalmx.com/photos/forums/2022/03/17/538631/s1200_11.jpg[/img]
Replicas available on eBay...
https://www.ebay.com/itm/265371735339

Maveric_Stant wrote:
Thank you out of ordering one I needed it rush..thank you very much.
Last2Stroke wrote:
Shipped, let me know if you have issues with it.

Are you the one that created the replicas?

Pit Row

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