Here's the model I purchased. It came with the below plenum that will be too long. I had to saw it to length to make it work. Wished I had a lathe but did it by Porta band and file and sand paper.. Not too bad. 
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FX Leaky FX Streamline Questions
- Thread starter Yardstick
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I saw that one on their website but hesitated to order because I wasn't sure when my rifle was manufactured. If they're basically the same but with different plenum lengths then that makes it easier. Cutting that part down might be the trickiest part for me. I used to have access to a lathe but not anymore. How much had to be cut off? And how did you figure out the correct length?
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I believe the final piece was like maybe 4 mm, can't remember exactly. Youtube instructional video says match up vents holes.. What I did was match up ctc the vent hole in tank with the HUMA vent hole. Did some quick math and that what I came up with. Guy at Utah Air confirmed my thinking ( not math).
Make sure you purchase a long 3mm screw to thread into regulator to be able to remove it from tank. And end the regulator with the pressure reading and adjustment is, goes in the tank first.. Have fun its not difficult and once you see the HUMA you will be glad you changed..
Make sure you purchase a long 3mm screw to thread into regulator to be able to remove it from tank. And end the regulator with the pressure reading and adjustment is, goes in the tank first.. Have fun its not difficult and once you see the HUMA you will be glad you changed..
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I contacted Huma directly to see what they recommended. They suggested using the Power Plenum set with their regulator. I have a fairly basic understanding of why that would be better. It won't hurt to try anyway. I'm considering getting one of their regulator testers too. It seems like that would be a good tuning tool to have for this and other rifles.
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Will be interesting to see how their power plenum works/ construction. Vent hole primarily.
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I was in Utah and happened to have some free time so I stopped by Utah Airguns. They had the Huma Regulator with Power Plenum for the Streamline so I got it while I was there (and an FX Crown, just for good measure! 
). The attached picture shows how I understand the regulator and power plenum to go together. I meant to have the regulator vent hole more visible but you can just see it a little behind the o-ring on the regulator. With the power plenum you only use one o-ring on the regulator and the other o-ring is on the power plenum. It's an interesting setup. I'm not sure what, if anything, this will do to the shot count or velocity. I'm expecting some improvement in consistency with the Huma regulator. And I'm expecting to need to do some amount of tuning to optimize things.
). The attached picture shows how I understand the regulator and power plenum to go together. I meant to have the regulator vent hole more visible but you can just see it a little behind the o-ring on the regulator. With the power plenum you only use one o-ring on the regulator and the other o-ring is on the power plenum. It's an interesting setup. I'm not sure what, if anything, this will do to the shot count or velocity. I'm expecting some improvement in consistency with the Huma regulator. And I'm expecting to need to do some amount of tuning to optimize things. Upvote 0
Ahh, so that’s how they configured it. Makes sense now. Plenum takes up space but you should have a nice reservoir of regulated air and should be more consistent. Removing the regulator might be interesting. I shot mine out with a slight burst of air into a very thick fleece pair of hunting overalls. Staying tuned….
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I have been thinking about getting the huma reg/plenum upgrade for my SL so very interested in your results!
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^^^ Great looking rig there!! The Streamline is a great platform and would be even better with a bottle and larger magazine. I think bottle might be doable but the magazine probably not..
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I was looking at an FX Dreamline that Utah Airguns had in Field Target trim that had a chassis rather than a regular stock. It looked a little bit like that. I wondered if the Dreamline regulator setup could be adapted to the Streamline. The Dreamline's regulator is in a tube that is the same diameter as the pressure tube and sits between the pressure tube and the receiver area. If you could just put that short regulator housing section on a Streamline you could have external regulator adjustments.
I ended up going with the Crown because it does have a bottle and an easy hammer adjustment for swapping barrels. I got .22 and .177 barrels with it to try a few things. I liked the GRS stock so I went with that but apparently there are companies that make chassis setups for them.
I ended up going with the Crown because it does have a bottle and an easy hammer adjustment for swapping barrels. I got .22 and .177 barrels with it to try a few things. I liked the GRS stock so I went with that but apparently there are companies that make chassis setups for them.
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I have some results to share. The short version is that the rifle is now spitting out JSB Exact Jumbo Heavy (18.13 grain) pellets at an average of 942 fps. I tried some hammer spring tuning. Reducing the spring pressure reduced the velocity but it didn't go down as much as I expected. Increasing hammer spring tension resulted in increased velocity until I couldn't adjust the spring anymore. I guess that means I could reduce the regulator pressure. I might wait to see how it does on a target before I get into more tuning.
Edit: I couldn't leave it alone - or rather, I had time and nothing else to do. It sounds like JSB Heavies like a lower velocity than where I ended up. Also, the Huma with the Power Plenum are holding pressure so that seems to have fixed my leaking issue. I decided to try lowering the regulator pressure to about 120 Bar. I don't have a pressure gauge (yet) so I'm going by Huma's tape indications. It was somewhere between 130 and 135 to start with. At 120 Bar I can still max out the hammer spring with no decrease in velocity, so maybe I can lower the pressure even more. For now it's at 120 Bar with the hammer spring backed out 1.5 turns from full in. That results in a velocity of 884.5 fps with the 18.13 grain pellets.
Edit: I couldn't leave it alone - or rather, I had time and nothing else to do. It sounds like JSB Heavies like a lower velocity than where I ended up. Also, the Huma with the Power Plenum are holding pressure so that seems to have fixed my leaking issue. I decided to try lowering the regulator pressure to about 120 Bar. I don't have a pressure gauge (yet) so I'm going by Huma's tape indications. It was somewhere between 130 and 135 to start with. At 120 Bar I can still max out the hammer spring with no decrease in velocity, so maybe I can lower the pressure even more. For now it's at 120 Bar with the hammer spring backed out 1.5 turns from full in. That results in a velocity of 884.5 fps with the 18.13 grain pellets.
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