S400 help

cowsmart

Well-Known Member
have the option to buy a S400 classic..at the moment no matter how much charge is in the rifle it hasn't got enough power to push a pellet out...any ideas how to fix this? or is it a trip to the gunshop? It does cock and fire, but sounds like a wet fart and blows as hard...
 
Sounds like the o-rings need a good servicing/replacement as a first action.....

My Daystate does that when the battery's low - but don't think the S400 has any power source in it?
 
how much charge are you putting in it? if you go too high the hammer will not fully open the valve, (of course if you go way too high the cylinder will distort and become useless:D ) 170 bar from memory is the preferred fill level
 
Best bet if you can't do it yourself is to look up Kevin Todd on the AAOC, he will sort it for you and it will come back a much better rifle than you bargained for.
 
I just thought there might of been a quick fix...only put 100 bar in it to try it...off to glenluce gunroom on tuesday to pick up my shotgun so i'll just take it along there and see what they say
 
I just thought there might of been a quick fix...only put 100 bar in it to try it...off to glenluce gunroom on tuesday to pick up my shotgun so i'll just take it along there and see what they say
from memory (again) 100bar is right at the minimum level, a bit below that and the reservoir discharges, try 170 and see what that does
 
from memory (again) 100bar is right at the minimum level, a bit below that and the reservoir discharges, try 170 and see what that does

I agree with the above. I have a s410 and the 'sweet spot' runs from 170 bar down to 100 ish, after which power drops off quite quickly.
 
Question... Have you filled up to recommended pressure... as stated in hand book... 190 bar... and is it holding air...

if you can hear air leaking from loading port or put soapy water around port... if bubbles appear then you have a leak and will need to replace the 2 O rings on the loading port.... caused by wear and tear...the O rings were worn.... that is what was wrong with mine it took 2 minutes to diagnose and repair. at the gun shop.

I'm led to believe that if the pressure drops much below 80-90 bar then the gun can dump all the air in the cylinder...rendering the gun inoperable..

David
 
Assuming it holds air ok, the valve, its return sring, the hammer and the hammer spring are ok, there are a couple of o rings which may be the cause. One seals the pellet probe (Bolt) the other seals the action to the top of the valve (transfer port). A leak of either will give you low power and in this case the gun will sound very loud. You'll need a chrono to check it. If it is a later gun it'll have anti-tamper on it which will need removing for most repairs.

It will be less than 80 bar when it dumps the air, probably 40 bar. This is a problem if you use a pump as it can be impossible to refill; no problem with a bottle as you can shock it shut with 200bar. In any case when this happens, make sure you cock the action before refilling as the pressure of the hammer on the valve will not allow it to seal.

Your average gunsmith wont know what to do with it.
 
Assuming it holds air ok, the valve, its return sring, the hammer and the hammer spring are ok, there are a couple of o rings which may be the cause. One seals the pellet probe (Bolt) the other seals the action to the top of the valve (transfer port). A leak of either will give you low power and in this case the gun will sound very loud. You'll need a chrono to check it. If it is a later gun it'll have anti-tamper on it which will need removing for most repairs.

It will be less than 80 bar when it dumps the air, probably 40 bar. This is a problem if you use a pump as it can be impossible to refill; no problem with a bottle as you can shock it shut with 200bar. In any case when this happens, make sure you cock the action before refilling as the pressure of the hammer on the valve will not allow it to seal.

Your average gunsmith wont know what to do with it.


makes me think i should stick to the old AA pro-sport i have and leave the 400 alone....at least with a spring gun its a simple cock and fire...
 
makes me think i should stick to the old AA pro-sport i have and leave the 400 alone....at least with a spring gun its a simple cock and fire...

Agree with other comments that it sounds like the seals have gone (I've an s410k that had that issue a few years ago). Get 'em sorted, and then remind yourself why you bought an air arms PCP.....'cos they are v accurate and easy to shoot!!
 
Sounds like a seal has gone. Couple weeks ago completly stripped my LR90 (FAC) and replaced the seals, now fine. Seal set was £5 from Daystate which included all the seals x2.

Just remember need to keep everything clean, dust free and no mineral oil as it could explode under pressure, use silcon based vacuum/high presure lubricant on all seals.
D
 
I had identical problem with my S400 which i had converted to 10 shot. Gun shop job in the end, can find out what the guy did if it helps
 
Inside the reservoir is a small chamber that meters each shot with a minute hole in one end, sounds to me like you have managed to get a lump of poo in there which will stop you getting a correct amount of air released upon the hammer strike.
Tw chambers do a seal kit if needed, but if its not too old you should get away with opening it up and having a look. They also post same day so you won't have to wait long if you do need parts.

The S400/410 series are very easy to dismantle and repair as far as pcp's go.
It's been a while since I've worked on one, but if memory serves me well, you can check the metering cylinder by removing the barrel band at the front and simply unscrewing the 'empty' air cylinder.

A lot of problems with pcp's is hand pumps filling with air with a high moisture content which then creates rust, which then drops off when you fill due to thermal and pressure expansion the next time you fill, and gets into valves etc, much better to use a divers bottle filled at a dive center where they have good moisture filters, and the air quality is checked reguarly.

If you have problems filling due to it lleaking out the barrel after it 'dumping' at low pressure, just cock the hammer to allow the firing valve to close.

hth
pete

edited to correct the 'auto corrected' spelling. Don't you just love iPhones ?
 
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