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Do you have the rubber boot with the head you have? If so what is the ID on the inner boot, Not the section that goes over the head port.
 

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Considering the XR650r edelbrock carb is only 40mm I wouldn't think it would flow more. The XX has a 44mm TB stock.
 

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I think the 40mm carb will flow more than the 44tb. I have ran 44mm carb on the XRs with great results. I just posted a couple of pics on the exhaust thread that are from a bike i did years ago. I think the XR head has more potential because of the dual exhaust ports.
 

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Discussion Starter · #26 ·
Thats my plan Tim, thats why I asked ya about duals being a possibilty on the XX chassis.
 

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Discussion Starter · #28 ·
I probably wouldnt either, supply and demand is not gonna be there. For the hardcore guys though, atleast they know who to turn to.
 

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Just got a measurement on the XR head intake port, It's the same as the XX. I wouldn't see it making any notable power gains considering the Intakes are the same. Tim or Bo, Do you know of anyone with a flow bench to test them and put this to rest or not?
 

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Sorry to butt in. VelociRaptor , me being a dumb ass on engine tuning and knowing far well you know ya stuff. Why build a billet head from scratch.
 

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It's not a problem to build one, The funds to do so is the hang up.
 

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Just got a measurement on the XR head intake port, It's the same as the XX. I wouldn't see it making any notable power gains considering the Intakes are the same. Tim or Bo, Do you know of anyone with a flow bench to test them and put this to rest or not?
The intake can be modified to flow what is needed but the twin exhaust ports compared to the single one will scavenge better it is easier to keep the velocity up in 2 smaller ports instead of one large one. I can get more technical if you want me to.
I will give this example of velocity in an exhaust.
We have a KX250F that we built for Don's Kawasaki in Pa. last year that makes 42hp to the rear wheel. I was playing with different exhaust head pipe diameters the stock one comes out at 1.375 then expands to 1.75. I built a head pipe that was 1.5 out of the head the same way the stock one was but 1/8 inch bigger and it lost 2 hp over the smaller one (velocity is the key to scavenging efficiently)
Hopefully this helps.
 

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I'm not interested in a billet head, I'd like to see some flow numbers though. Did you port the EHS head? If so, did you flow it?
 

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The intake can be modified to flow what is needed but the twin exhaust ports compared to the single one will scavenge better it is easier to keep the velocity up in 2 smaller ports instead of one large one. I can get more technical if you want me to.
I will give this example of velocity in an exhaust.
We have a KX250F that we built for Don's Kawasaki in Pa. last year that makes 42hp to the rear wheel. I was playing with different exhaust head pipe diameters the stock one comes out at 1.375 then expands to 1.75. I built a head pipe that was 1.5 out of the head the same way the stock one was but 1/8 inch bigger and it lost 2 hp over the smaller one (velocity is the key to scavenging efficiently)
Hopefully this helps.
So you're saying theres a chance?

Someone should definitely give this a shot and find out if its worth it. Awesome!
 

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hey why dont we put like 10 dollars each to BO if that would help with this project although i have no clue how much he needs to try to make this project work:disgust:. what are the thoughts on this i think if we get enough people it will help BO with creating a beast of a head.:D What do you think BO would help the most i just want to see this work out since our head is or was limited:hey:
 

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Discussion Starter · #40 ·
I just need a junk head. I was gonna handle all the TIG work and porting. I talked to someone that has a junk head, just waiting for it to come in.
 
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