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m102404 · July 11th, 2012, 09:43

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

.

July 11th, 2012, 09:43	#25
m102404 Tys Trader rating Join Date: Apr 2006 Location: Toronto	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 .