AEP low fps on M80

[Samurai]

Hi,

I bought one of these new cyma AEPs with the lipo, FET and strengthened stuff in it with the plan of making it shoot harder.

I did the shimming and air seals, and eventually got an M80 AEP spring for it. It shoots 230 fps with it. It should be 280 at least.

 

When I put the gearbox together without the spring, and cover the nozzle on both ends, it's hard to push the piston forward, so air seal should be OK. Obviously it moves freely when not covered. The nozzle goes into the bucking nicely, not pinched and when I add a spacer to the nozzle return spring, the fps doesn't change.

 

I cut down many vsr springs and created spacers for them too. Even with springs I could hardly force it into the box, the maximum I got was 240 fps.

 

It must be the air seal somehow. The o ring between the cylinder and cylinder head is too thin, it doesn't seal so I put teflon tape on it, but doesn't feel right.

I'll order all the o rings in proper sizes but if anyone had some good advice, I'd appreciate it.

[Rogerborg]

I feel them feels.  I'm also getting about 230fps either from a full M80 spring, or from a a cut down one.

 

So it's got to be air seal, right?

 

But you said that you get good seal when you cover both ends of the nozzle, so the piston seal must be OK.

 

I'm still suspecting the air seal at the rear of the nozzle, as per...

 

 

... but to my chagrin, I didn't get around to trying the suggested bodge as I discovered the joys of GBB and threw the AEP into the Bag of Perpetual Ignorance.

 

There are a couple of video out there claiming nearly 300fps from that M80 spring , but nobody seems to be talking about they got the air seal spot on.

[Samurai]

I tried blowing down the barrel and seemed to still get the OK seal, so the spring guide seal should be good.

I'll report back after changing the O rings.

I have a reliable guy who got 280 out of it without a small diameter barrel. With a 6.01 300 is achievable they say.

[Rogerborg]

Thanks, that'd be great to hear.  I didn't try a better barrel because I reckoned I should be seeing more just out of the spring.  If we can find the secret sauce, I might return to fiddling with it.