Umarex Notos tune, the beginning

[Rohmpm]

All ports at .154.
Milled air tube adapter at an angle, .375. Standard passage from reg to valve was tiny, no wonder plenums do so little.
Machined trigger/handgrip housing to allow backing hammer spring adjuster out.

Horrible crown, shortened barrel 1/2 in.
Reg as received. Adjuster flush.
14.35 JSB
849, 852, 852, 849, 849

15.89 JSB
813, 817, 815, 820, 815

25.39 JSB
663, 664, 667, 667, 665

21.14 Barracuda
737, 736, 738, 738. 738

15.89 JSB one turn in
831, 823, 828

2.5 turns out
785. 789
So, up to 25 ft lbs with at least 2 mags, maybe more. I didn't do a shot count.
I'm confident that the 15cc plenum and reducing set pressure, lighter hammer and spring will work great.
More to come.

 

[Rohmpm]

Ran another mag. 3500 psi to 3000

 

[Rohmpm]

The post may have been misleading. The airtube adapter port is milled at an angle as the passages do not line up.

 

[wendell]

Watching!

 

[TC724]

I have trouble picking a pellet I want and here you are re-engineering it! Glad to see guys like you can do it!

 

[Rohmpm]

Found a tin of JTS Dead Center 18.1 gr pellets. 7 shots averaged 778 for 24.3 ft lbs. Turning g the hammer adjuster two turn in from flush averaged 788, and a lot louder.
Two turns out from flush, just tried 3 shots. 733, 733, 743 and much quieter. Even at that , near 22 ft lbs. Based on these results, it clearly needs a plenum with the larger porting. So, it was easier to order the plenum than make one so I'm done for a few days.

 

[Firewalker]

Love the JTS 18.1gr pellets, better groups than JSB of any weight.

I'd like a small plenum too but don't want to lengthen the gun anymore.

 

[Rohmpm]

Tried a little trick. Thinned down the valve shaft to allow more area in the valve.
18.1 Dead Center pellets
Adjuster flush
790 for 25.1 ft lbs

Adjuster out two turns
780

Adjuster in two turns
793.

Just waiting for the plenum.

 

[Npis2001]

Awesome work. What is the valve shaft and how did you thin it down? Got a picture?

 

[Firewalker]

Tried a little trick. Thinned down the valve shaft to allow more area in the valve.
18.1 Dead Center pellets
Adjuster flush
790 for 25.1 ft lbs

Adjuster out two turns
780

Adjuster in two turns
793.

Just waiting for the plenum.

It's so tiny with that brass cone, I'd like to see a pic too.

 

[Rohmpm]

Added the plenum. Interesting.
JTS 18.1
Adjuster flush
835, 840 Over 28 ft lbs!

one turn out
835, 833. Clearly it on the plateau where more air gives nothing.

Two turns out
830, 828

Three turns out
817, 813, 816

Four turns out
809, 799, 803

Five turns out
786, 775, 778
About five percent below the plateau where rsterne says to be.

I know someone would ask
JSB 15.89
Flush adjuster
884, 875, 881 27.6 ft lbs.

Five turns out
824, 828, 836

Getting into range of slugs?
Adjuster flush
FX Hybrids, 22gr
744, 737, 737.
Going to order lighter slugs.
Accuracy testing after I finish a muffler.

 

[Rohmpm]

Machined the valve body down to the valve seat line. Valve, transfer, barrel drilled to .154.
Some would drill .186, 20% of bore.......I question the valve area and at this point, I cannot bore my valve body any larger. I could have had I not machined the valve for possible increased flow. I'll order a new valve.

 

[Firewalker]

Machined the valve body down to the valve seat line. Valve, transfer, barrel drilled to .154.
Some would drill .186, 20% of bore.......I question the valve area and at this point, I cannot bore my valve body any larger. I could have had I not machined the valve for possible increased flow. I'll order a new valve.
View attachment 386138

Please let us know if you are able to get parts, I have not seen anything come from Umarex so far.

 

[Rohmpm]

Please let us know if you are able to get parts, I have not seen anything come from Umarex so far.

I'm hoping.

 

[Npis2001]

After drilling the holes, there is a slight burr. Is it important to clean the burr? If so, how should it be clean for both the outter and inner side?

 

[rdpjr6504]

This is the valve from a PP750. The same as NOTOS. Wes at AIRGUNARCHERYFUN can get parts for the PP750. I have both apart the PP750 and NOTOS and some parts are the same. Except for levers on different sides and the PP750 barrel has a thimble and screws on.

 

[kd1yt]

I have a Snowpeak PP750 (Notos by any other name) and bought a claimed-"improved valve" from a vendor on eBay (not sure if it is OK to mention vendor name here). The improved valve has a beefier stainless stem and a more robust main body of the valve, and less taper area at the valve seat. Maybe this would allow more flow? Have not had a chance to install the valve in mine yet

 

[Rohmpm]

I have a Snowpeak PP750 (Notos by any other name) and bought a claimed-"improved valve" from a vendor on eBay (not sure if it is OK to mention vendor name here). The improved valve has a beefier stainless stem and a more robust main body of the valve, and less taper area at the valve seat. Maybe this would allow more flow? Have not had a chance to install the valve in mine yet

I only found the poppet valve, something easy to make. I could make a peak valve that would work with my valve body but I prefer to keep my existing body as is. Wes is out of stock on PP750 valves.
I believe that with .170 porting and a larger bore valve body, 30+ftlbs would not be surprising. The existing hammer spring would work well as it's considerably oversprung as modified.
Think I'll get another and use a two inch longer .25 barrel with .190 porting. More power, still very light.

 

[rdpjr6504]

Just put together a .25 NOTOS. Used a KRAL 16 inch NP-03 barrel and waiting on CARM mags and bottle to arrive. Also working on a .177 conversion waiting on parts from Wes also using a KRAL NP-03 16 inch barrel.

 

[Rohmpm]

Just put together a .25 NOTOS. Used a KRAL 16 inch NP-03 barrel and waiting on CARM mags and bottle to arrive. Also working on a .177 conversion waiting on parts from Wes also using a KRAL NP-03 16 inch barrel.

Where are you getting the Kral barrels?