Hw 90 Power

[nellie123 4]

Does any body have any experience of adjusting the power down on a hw90?

A mate of mine has picked one up second hand (one of the early models i think),and hes put a few different pellets though,and he says that he thinks its pushing the limit and a bit harsh.

so i thought id ask on here if its easy enouh to do,ive found the valve at the back of the action.

 

thanks

[Rez 4,961]

So its yours then?

 

Id personally re build it, empty the pressure from the ram and re pump it to a lesser set pressure using a pump. It'll be set you see, so theres now taking it apart and adjusting as with a spring as you'll know, the ram itself is self contained. Im not 100% on the 'set' pressure of a 90 to be honest. My old Fenman was running about 780PSI pressure. Anything over 1000PSI and you risk it turning out very gay and it'll bugger the ram anyway.

 

Is it a HE model?

 

http://www.bestfittings.co.uk/shopexd.asp?id=638

[nellie123 4]

Im not sure weather its the HE model,i think it was originally bought new in 1994 i think.

i have suspension pump that is schrader a valve,or will it need a pump meant for purpose

thanks

[Rez 4,961]

Any Theoben orientated pump should be fine man.

[carlstoke 34]

Take the screw from the valve and tap it gently with a parallel punch and small hammer, dont hit it to hard or you will lose all the pressure, test with a chrono.

[offtheradar 175]

Im not sure weather its the HE model,i think it was originally bought new in 1994 i think.

i have suspension pump that is schrader a valve,or will it need a pump meant for purpose

 

If you mean an mtb suspension pump then no I'm afraid that won't have the pressure to fill it. I think the original was called a slim Jim and they were used for the theoben gas ram and brocock tac cartridge

Edited February 9, 2016 by offtheradar

[pratty 9]

You can buy the pump from best fitting.if its less power you want take the screw out the back and tap the valve to release air till you get the power want it.the 90s have got a bit of a kick to them.

[nellie123 4]

Thanks for the replies,ive tried to let some air out gradually,buthe valve is quite sensitive and the power has dropped to 8 ft/ld,so its now at redbeck shooting suppliers getting re gassed

[magnummike 39]

You will need an adaptor to serew in to the threaded hole were the valve fits you can buy them , I got one but not sure where from now they fit in to a standard airgun pump . I wouldn't fill with a bottle as the pnmp is much more controllable think I pumped mine to about 12 bar , but start lower and test as you go but not 100% sure I'll try to find out for you as too much pressure can blow the seals on the valve as I found ,

[magnummike 39]

Reading an old Hw90 stripdown guide on another forum says the start point he uses is 200psi then tests . 12bar = 175psi so I wasn't far off think he starts a little high to work down , makes sense saves pumping more than once hope this helps , Mike

Edited February 16, 2016 by magnummike