HW/Weihrauch Hw90 .25 tuning transferport help

[Theoben Eli.]

Hello,

Im made a hw90.25 with a little more swept volume.
Orginal 30x85mm 60cc
Now 30x90mm 63.5cc.
Found the transferport is only 3.0mm
Im think this is little to small for the powerplant.
Im planning to dril it to 3.2mm
Its now shooting 750fps with ftt 20 grain pellets at 20 bar ram pressure.
Some info needed on transferport size and influnce on power.
its now a full 500mm barrel im plan to go 400mm and a supressor on it.

 

[Mycapt65]

That's already 25 fpe. I'm not sure you're gonna see more energy that out of that rifle. I don't recall hearing 90s make more energy than that at 20 bar. There are much smarter people here than me but I've never messed with TPs because its easy to got backwards fast and they're hard to fix.

Also are you sure of that stroke? I was under the impression the 90 stroke was over 100mm from the factory. I never measured mine so I cant confirm that.

 

[Mycapt65]

I don't think barrel length will affect power. 25 is a big bore so it eats up a lot of that swept volume quickly.

 

[A.G.R]

Any pics? Did you re machine the piston face. ?

3.5 mm with a 90 mm stroke will give less back pressure recoil.. THE INERTIA WEIGHT is a big player. I don’t play into Cardews theory as it was tested on a short stroke HW 35 . Longer stroke .25 need to breath a bit
I would start at #29 drill bit. As the float will give a 3.5 mm port. Any of my bigger guns use at least that..

Doing port work with unknown guns is tricky. I’ve ported some 30 ft lb plus’s guns at .171. That being said it wasn’t haphazard guess .. it was after testing many of the different set ups with many of the same gun

generally .152 is what Webley Patriot, stock ,, in 25 used with a 114 mm stroke. Weight of the inertia plug and seal design and fit will be a factor

It’s not so easy to work on one gun and test.. You need several to test against.

that being said .3.5 will be better as every . 22 HW 80 with a 80 mm stroke benefit. YMMV.

 

[Theoben Eli.]

No pictures, when im working on it im in a perfect zone.
Yes im shortend the front of piston by 3mm.
Also made the sear by 2mm thicker.
After that some little things, like chocking shoe.
Mine hw90 mk1 have 85mm storke lenght.
Im also did a aussie red piston seal, the no pacacute one.
Its dieseling very little now, im first clean it then do next 20 shots. At 20 bar
Im thinking by the extra 5mm stroke the air ia getting hotter, youre pushing more volume thru a small hole causing friction.
Thats why im thinking in to enlarge the transfer port to lower the air temp and up in flow.
Goal is a solid 25-26 fpe at 20-21 bar.
Mine eliminator have a 100mm stroke by 31.4mm diam at.65 bar ram pressure its do .22 ftt 285ms

 

[Theoben Eli.]

Im removed the interia weight
By lower the piston weight.
So a tp of 3.5mm is best size?

 

[Mycapt65]

Did you measure the actual stroke length? It's listed as 106mm on another forum post. I wouldn't die on that hill but I'm curious to what it actually is.
Thanks

 

[Mycapt65]

Also, opening the transfer port reduces peak pressure, which reduces heat from compression by itself. The tighter you squeeze air quickly the hotter it gets. So opening the port should reduce peak heat. Regardless of size that gun squeezes air tight enough it will always diesel if there's something to burn in there. I'm sure you know all this and have a handle on it. Just posting for general viewing.

 

[Theoben Eli.]

Yes im measure the stroke its 85mm.
Not 106mm
MIne eliminator have 100mm

 

[Mycapt65]

Yes im measure the stroke its 85mm.
Not 106mm
MIne eliminator have 100mm

Thanks. I got bad Information on the internet. Who'd thunk it? Lol

 

[Theoben Eli.]

Yes, its 85mm

 

[silverstreak]

It has been written of the 90 to have a stroke over 100mm, but pretty sure it is a typo- it uses the same barrels as the 95-80... The pivot pin to link distance will never allow that much swing. Would need a longer block. I have seen pics of some having a second linkage hole, but it was closer to the pivot for a shorter stroke. Thinking it was a UK rifle.

 

[Theoben Eli.]

If the stroke lenght where 106mm
Than power must been almost same as theoben eliminator.
it do around 21-22fpe .22
At 22 bar rampressure.
So stroke is shorter than 106mm.
Im measure it preciesly 85mm
Back in time im did long stroke hw80
30x85-86mm so 6mm more stroke.
It runs 23fpe .22

 

[Theoben Eli.]

After some time im found a notex piston seal for hw35 80 90.
I order one to test if its better then cup seal from aussie.
is it already tested here?

 

[A.G.R]

After some time im found a notex piston seal for hw35 80 90.
I order one to test if its better then cup seal from aussie.
is it already tested here?

Cup seals if fitted right are the best shot cycle for big guns..parachutes seals are horid designs for powerful as more you push the more they push baxk

port it to 3.5

 

[Arzrover]

A lot of years ago, Maccari drilled and tapped the transfer port and used some grub screws with different sized holes drilled in them to experiment.
I've kept that in mind for a couple of my project springers that seem to have oversized ports as a method to repair... but have not taken time to actually do it yet...

Interesting project... good luck...
Bob

 

[Theoben Eli.]

Yes beeman r1 tested the interchange tp size.
Im go small steps tp drill to 3.2mm
New notex piston seal.
Agr youre say TP 3.5mm for mine hw90

 

[Theoben Eli.]

Some pictures,
Its full 500mm barrel the silincer im made it push over style 100mm internal

 

[Mycapt65]

Some pictures,
Its full 500mm barrel the silincer im made it push over style 100mm internal

View attachment 501862

View attachment 501863

View attachment 501864

Very nice job. Looks classy. Well done.

 

[Theoben Eli.]

Thanks a lot, just fideling around.
The snapp sound is now bit less.
Only 100mm of silencer is working.