hw90 mods/tune/lubes

[slugger]

just about to go pick up an hw90 and me being me will fire a pellet or 2 before giving it a strip down/full service
while its apart, are there any "must do" mods ? transfer port sizing ? trigger mods? that sorta thing..
also, in my theoben evo i remember putting some oil inside the ram for lube, then moly on the piston etc as usual....... same sort of deal for the 90 ?
and lastly...... is the fill pressure going to be similar [800 psi ish in 177] for low 11's ?
ta

[joffy]

Should've bought a hw80

[slugger]

already had one of those decades ago ... not had a 90 before, i kinda hoping it will be everything i love about my evo........ but with a better trigger

[DCL_dave]

Whilst you have it apart, check to see if the inertia weight moves within the piston....if it's stuck solid (as mine was), remove it, reassemble and try it out...firing cycle should be a little quicker and less thumpy...(thank Jon Budd for this idea)

I have 2 HW90s...an untouched .22K and a .177 with weight removed (and a heavy 98 barrel fitted)...they both have similar recoil and firing characteristics for roughly the same power (with .5fpe of each other)

[joffy]

I liked the look of the tb euro ......why couldn't they put that style of stock on the 80 and 77/97 ....might've had a good seller there

[DCL_dave]

Been playing around with my .177 recently...trying to fit a front sight on a 98 barrel to match a Williams peepsight...this sort of works but is only in the mock-up stages...I plan to drop the power to around 8-10fpe (where it will have very little recoil) and use it in my garage

[maximus]

just about to go pick up an hw90 and me being me will fire a pellet or 2 before giving it a strip down/full service
while its apart, are there any "must do" mods ? transfer port sizing ? trigger mods? that sorta thing..
also, in my theoben evo i remember putting some oil inside the ram for lube, then moly on the piston etc as usual....... same sort of deal for the 90 ?
and lastly...... is the fill pressure going to be similar [800 psi ish in 177] for low 11's ?
ta

The 90 has a lower fill pressure than an evo. Cant remeber how much exactly though but fairly quick to do with the hand pump rather than off a bottle. All I did with mine was a standard polish and relube plus fitted one of the new HW piston washers. Will always have a substantial recoil due to the heavy, mega heavy infact, piston.
Personally I like them and can shoot accuratly with one despite the chunk of recoil. Never mentioned in the "best out of the box" debates but got to be up there due to how smooth and quiet they are.

atb

Max

[DCL_dave]

The 90 has a lower fill pressure than an evo. Cant remeber how much exactly though but fairly quick to do with the hand pump rather than off a bottle. All I did with mine was a standard polish and relube plus fitted one of the new HW piston washers. Will always have a substantial recoil due to the heavy, mega heavy infact, piston.
Personally I like them and can shoot accuratly with one despite the chunk of recoil. Never mentioned in the "best out of the box" debates but got to be up there due to how smooth and quiet they are.

atb

Max

Hi Max,

If yours has excessive recoil, then it is possible that the inertia weight is tight and not doing it's job properly? ..from memory, the inertia weight is about 90-100 grams or so..and if it's not moving then it does add a lot of weight to piston!....costs nothing so it is worth removing it to see if recoil is reduced (worked on mine )

And yes, think ram pressure is about 20 bar or so?...guage is a bit duff on my old stirrup pump so I'm not sure...usually just pump it up and run it over the chrono to be sure. My .177 has one of those red Aussie seals fitted, seems to work well with good shot to shot consistency!

[pjinoz]

just about to go pick up an hw90 and me being me will fire a pellet or 2 before giving it a strip down/full service
while its apart, are there any "must do" mods ? transfer port sizing ? trigger mods? that sorta thing..
also, in my theoben evo i remember putting some oil inside the ram for lube, then moly on the piston etc as usual....... same sort of deal for the 90 ?
and lastly...... is the fill pressure going to be similar [800 psi ish in 177] for low 11's ?
ta

Max fill pressure was 26 bar (about 370 psi); I used to run mine @ 25 bar and cocking was not that easy. These sort of ram pressures are FAC! Mine was in .22 and ran about 27 fpe; what ram pressure would be for "low 11's" ???????????? Externals of piston high moly but O ring ram seals required a special lube.

Happy shooting

[slugger]

nice one lads....... ive got it home now, so we know what im doing this arvo

[maximus]

Hi Max,

If yours has excessive recoil, then it is possible that the inertia weight is tight and not doing it's job properly? ..from memory, the inertia weight is about 90-100 grams or so..and if it's not moving then it does add a lot of weight to piston!....costs nothing so it is worth removing it to see if recoil is reduced (worked on mine )

And yes, think ram pressure is about 20 bar or so?...guage is a bit duff on my old stirrup pump so I'm not sure...usually just pump it up and run it over the chrono to be sure. My .177 has one of those red Aussie seals fitted, seems to work well with good shot to shot consistency!

Hi Dave, I think mine is working as it should, I have 2, a .25 and the .22 90TB which I recently had in bits, both shoot nice but must have recoil due o the weight of the piston. As its working fine I don't want to strip it again but its interesting that removal of the weight reduces recoil. I think the aim was to reduce piston bounce and hence "surge" as Jim Tyler puts it! Incidentally, mine had the hole through the inertia weight. Under-rated guns though a bit pricey new. Custom stock actually will make stocks for them too so they can look really nice

[joffy]

Hi Dave, I think mine is working as it should, I have 2, a .25 and the .22 90TB which I recently had in bits, both shoot nice but must have recoil due o the weight of the piston. As its working fine I don't want to strip it again but its interesting that removal of the weight reduces recoil. I think the aim was to reduce piston bounce and hence "surge" as Jim Tyler puts it! Incidentally, mine had the hole through the inertia weight. Under-rated guns though a bit pricey new. Custom stock actually will make stocks for them too so they can look really nice

i'd be interested in a high res pic or two of the tb stock if you have one .....pretty please

[maximus]

i'd be interested in a high res pic or two of the tb stock if you have one .....pretty please

Don't know about "high res" but I'll take a pic

[slugger]

stripped / cleaned /relubed and rebuilt........ a bit of ironing [stock] and fettling of the trigger. and voila, shot cycle nice and fast, set to 11.5 for now [may drop it a tad more later]....... and you guys are right, its a much lower pressure than the evo [dont even ask how hot it went at my first guess of half-evo-pressure]
anyways, its nice to have the 2 side by side for some comparisons,,,,,,,,,
evo is the lightest [and shortest] and therefore would probably be the better hunter.
the evo looks nicer, more modern [despite being older]
and the evo shot cycle is a little faster....... you have to try them back to back several times to feel it, but is. possibly making it less hold sensitive ?
.
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the hw90 is easyer to cock.
its less 'clanky' for want of a better word........
it has a screwcut barrel [so you can have any silencer you fancy]
its heavyer so may counteract the slower [only just] shot cycle in terms of hold-sensitivity.
and the trigger is far superior to the evo. both in terms of adjustability and feel
the re-settable safety [while making the trigger guard overly bulbous] is actually very good....... its easy to use, has good positive feel, and is well engineered [going to last]

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.
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so far its neck and neck.......[as far as im concerned] . they are both stunning fast locktime wise [faster than any short stroked springer ive tried] and therefore are very easy to be accurate with [in theory]
in practice i know the evo is very accurate........ to silly ranges, i think the pellet has left the vacinity before all the comotion of recoil even takes place [or at least thats how its percieved] . but i have yet to test the 90, i have a feeling it will also group well, and more importantly be easy to group well. but i cant post comment untill i get it on the perm with the targets later in the week.
but so far, i am very pleased with the new to me 90........ build quality is way better than average for weihrauch........ the cocking slot has zero burrs, and refitting the piston with its seal slowly heading down the chamber past all the cutouts was smooth and snag free........ no need to poke the edge of the seal down to 'clear' any nasties, and likewise no need for a session with the files and wet n dry........ tha action has wording on it, and the numbers tally to circa 2010 [so its a relativly new one] this tells me they must make an extra special effort at the factory to ensure a glitch-free rammer.
in any case im impressed by the quality of the components... the actual tank-like evo is a little more robust perhaps, but quality wise i think they are on a par........ to put it another way, if you were to have both in fac levels, i think the evo would cope better/longer, but sub 12, nothing in it. i have a good feeling about this 90, i think we are bonding already lol
cant wait to get some pellets down range with it

[maximus]

"the hw90 is easyer to cock."

I am surprised you say the 90 is easier to cock than the Evo, I've always found it to be the other way round! My .25 is particularly hefty on that front! Glad you are happy with it, they have a very pleasant firing cycle in my opinion.