Low FPS

[CDN_Stalker]

Already? Was said to be brand new! Lol

[Danke]

Like Vizzini says, "You go back to the beginning".

[CDN_Stalker]

JG quality control is that bad, eh? Oh wait, is that expecting too much from JG? Is possible!

[KBarlow]

Originally Posted by Trev140_0

My brand new G&P box I got the other day had nearly ZERO compression. Had to open ip up, put the o ring over the cylinder (to stretch it) gave it a few good hits with a lighter, and put it back together.

My bet stands.

O ring.

I'm going to try this with my VSR after I drill the end cap out a bit. It should be shooting like 450, but it's more like 330. New o-ring. Lighter. Check.

[KBarlow]

P.S.
I like boobs.

[CDN_Stalker]

Originally Posted by KBarlow

I'm going to try this with my VSR after I drill the end cap out a bit. It should be shooting like 450, but it's more like 330. New o-ring. Lighter. Check.

Cut off the piston brake, common VSR issue, heavy spring, still shoots 330fps. Cut it off and realize what you've been missing (piston brake is there due to Japanese standards of 1 Joule bs, aka, 330fps with a .20g BB). If you don't have a piston brake anymore because you cut it off or totally replaced the piston and the head, disregard.

I love boobs too. Maybe that's why we've been struggling with helpful info for you, easily distracted males...........

[KBarlow]

LOL

Ok, where would said piston brake be?

[Kos-Mos]

It's the pin in the center of the piston face.

Cut it flush or leave 4mm if you want a quieter gun.

[KBarlow]

Pretty sure there's no pin.

Had the cylinder apart the other day. What I think it may have been was the BBs hitting the end cap. Just drilled it out so I can see the edges of the barrel now (obviously taking the barrel out first). Gonna have to re-chrono it.

[m102404]

If you're at the point where you're just sick and tired about taking your whole gun apart to take the mechbox out to take it apart to troubleshoot AGAIN...

Check over the mechbox...check the compression as best you can. Even by hand you should be able to push the piston in fast enough to generate an airseal. Check with the nozzle off...with the nozzle on. A little/slow leak with the nozzle on (in the extended position, not pushed down all the way on the cylinder nozzle) is ok...it's tough to get 100%/super-perfect/airseal everytime without lots of spare parts to sift through. If you've got an issues there...fix that first.

Once you've got the mechbox all buttoned up...put on just the grip, motor/motor plate. Adjust the motor height so it's nice.

Then take the complete hopup/inner out of the gun and fit it to the mechbox. The rim of the hopup unit should seat flush with the opening of the mechbox. Some units are too large and sit away from the mechbox...some are casted badly and don't sit flush either. The old DBoys ones used to be off-center and not fit a variety of shells. The spring on the hopup pushes against a notch in the outer barrel to "force" the hopup unit flush against the mechbox and create a good seal between the nozzle and hopup unit. What you're doing is simulating that out of the gun.

You can quickly rig up a jig by driving a couple of nails into a board...but I just hold it all by hand.

If it's all good and flush, you can drop some BB's into the feed tube (usually takes 4-5) and use light finger pressure to keep the BBs in the feed tube (they'll want to pop out when you shoot....wear googles). Then shoot through a chrony. If you're getting the FPS you expect...then the issue is with the body/barrel/stock/grip setup when assembled. If that's the case...I'd try a different mechbox make.

If you're not getting the FPS you expect...then I'd first try another hopup unit/rubber/inner. And if it was still low, that'd point to a mis-match with the nozzle, I'd open the mechbox again looking at the nozzle/tappet (there won't be much to look at with the cylinder/piston head/cylinder head....since you checked that out already). Since it's hard to physically see an good/bad airseal between the nozzle tip and rubber...I'd just swap the nozzle and test again.

Since you're working with a BNIB mechbox, although it's not unheard of that it could be a dud, I'd be looking straight to the hopup unit and rubber. I'd first swap the hopup rubber with a different make/brand...I'd make sure the hopup was set almost off (just enough to hold the BB from rolling out). If it was still wonky, I'd try a different hopup unit.

Best of luck

.

[horto]

Originally Posted by m102404

If you're at the point where you're just sick and tired about taking your whole gun apart to take the mechbox out to take it apart to troubleshoot AGAIN...

bring it to tys!

[KBarlow]

I prefer the "buy a high quality gun" approach, but some people insist on buying shitty low-end guns or mixing and matching parts, and I am one of two people in this city left to fix them.

[Trev140_0]

so did you close in on the source of the problem?

[CDN_Stalker]

Originally Posted by Trev140_0

so did you close in on the source of the problem?

No kidding, eh? Silly us, anticipating the result to see who was correct. Lol

[Trev140_0]

ya-- I was a little interested in this as well.