Air Gun Home :: View topic - Anyone convert a single stroke pumper to a multi-stroke?

AirGunEric · Site Admin

Just like the title- anyone know about converting a single-stroke pneumatic to a multi-stroke and what is involved with this? I've never, now that I think about it, had an SSP gun apart to look it over and see what can be done.

DerekVinyard · Member

Sounds like a fun idea, if you can find a good candidate to work on. You simply need a valve that can handle a little more pressure and a check valve in between the piston and the valve.

jonathan · Member

This is creepy.....I was gonna make a post about the same topic. Was looking at a Daisy 953 and wondered if the valve could be adapted to multi pump......... Shocked

Slavia · Moderator

I've got a Daisy club box with two Avanti 853's and two Avanti 840's (Grizzlies with peep sights). Also a Marksman 2004 pistol. All are SSP's, and all are missing any kind of intake valve. The piston is what holds the air under compression, and the pistons travel almost to the cylinder heads.

Nothing is impossible, but at least on these guns you would have to sandwich an intake valve into an already crowded exhaust valve body. Maybe not impossible, but it would be way easier to get a MPP in the first place.

AirGunEric · Site Admin

No, what's creepy is I was also thinking about a Daisy as the candidate for this...

Slavia · Moderator

I don't think it would be worth it, and this is coming from a guy that has modified nerf guns. But believe me, I would love to be proven wrong.

Slavia · Moderator

This is an Avanti (Daisy) 853. The single shot, not the 853C "clip" model. It is very accurate with its Lothar Walther barrel, and has enjoyed popularity as an entry 10m gun with groups like 4H and the Boy Scouts. At 500 FPS it works great - but let's see what's in there:

The exhaust valve and the transfer port are right at the cylinder head. In fact, the exhaust valve spring retainer clip is flush with the head. No room for extra stuff there:

The cylinder is an aluminum sleeve inside a stamped steel tube, sealed at the head end by an "O" ring:

The cylinder sleeve walls measure 0.030" thick:

An intake valve would have to go in the cylinder sleeve, which would necessitate shortening the piston stroke. So after you get that figured out, and after you beef up the sleeve to take extra pressure and mount the extra valve, and after you figure how to keep it from expanding away from the "O" ring seal, and after you modify the valve and hammer to take extra pressure, you would have - a Crosman.

AirGunEric · Site Admin

Ah, crap- I was hoping for an easier time of it! We'll lay that oneon the back-burner for awhile...

DavidSaunders · Veteran Member

Not the Daisy's, though a lot of people have had success with turning the Beeman P17 into a MSP (including myself), and it makes for one hard hitting pistol Smile

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I wish that the Daisy SSP's could be brought up a good bit further, as I prefer the Daisy MSP's for hunting and plinking (I mod mine for increased power and improved accuracy). I primarily use the Daisy 880 and 22X for rifles.