Piston head finger test..

[Amos]

I would suggest just buying a MASK cylinder head with the pre-installed sorbo.. It'll save you alot of trouble.

[shiftline]

Along with the modify cyl or just keep stock and buy the piston/pistonhead/cyl head

[shiftline]

Since im pretty sure the SORBO is what caused all the pain and suffering I think for now i will remove it and just replace the cylinder.

[coach]

Just avoid cold weather gaming and you're less likely to crack your mechbox again.

I learned the hard way a few times but am loving my FrankenMP5 with both the piston and cylinder head with sorbo's installed.

[Blackthorne]

Originally Posted by Amos

... Wait, you put a sorbo pad on the piston head?

WELL THERE'S YOUR PROBLEM!

It goes on the cylinder head.

Can't believe I missed that...

[shiftline]

hah yea, sad but ture, i missed it to.. Is it worth putting it back in? or just go back to stock setup and file off a tooth

[Azathoth]

By looking at your gearbox pictures I don't think it's worth your money to buy a 75 compression set. What spring are you running? Since you are running some kind of aftermarket reinforced box I recommend a full tune up kit or a complete brand new pre built box from a good manufacturer.

Your Piston is likely stripped on that tooth because of the sorbo pad.

As to your suck back problem TM and G&G Piston heads are non ported and rely on a larger O ring to get the compression on the release of the piston. Aftermarket (almost every other manufacturer) makes ported piston heads (excursively) and have slightly smaller o rings on their PH's. The forward stroke of the piston and the ports cause the O ring to inflate getting you the airseal.

It is a extremely common DIY Mod to TM piston heads to drill port holes 4-8 to increase the compression and decrease the vacuum of the piston being brought back to fire the next round.

[shiftline]

Wouldnt drilling hole also decrease the air compression to fire the bb?

im running a pdi 170 spring

[Azathoth]

Originally Posted by shiftline

Wouldnt drilling hole also decrease the air compression to fire the bb?

im running a pdi 170 spring

No the opposite is true. The holes put pressure on the o ring expanding it against the cylinder walls. If this didn't work well, there would be literally no ported piston heads on the market. The market is dominated with ported PH's

[shiftline]

so you draw small holes on the outer diameter where the o ring sits?

Does it make a big enough difference to drill out mine tomorrow night :P

[Azathoth]

Originally Posted by shiftline

so you draw small holes on the outer diameter where the o ring sits?

Does it make a big enough difference to drill out mine tomorrow night :P

I'm not going to spoon feed you but go and find a picture of a systema, prometheus or modify piston head and make small holes at regular intervals around the PH. You don't want massive holes thumb tack sized spaces are good enough

[shiftline]

Found the Thread on it if anyone is interested

[m102404]

Keep in mind too that Illusion's quite accomplished with working/tweaking and tuning guns...and that he was using a TM piston head (in likely a TM cylinder), and TM's are near famous for nice compression out of the box. All told he probably had that rifle working really sweet ported head or not.

On sloppier sportline/clone stuff now, you're likely to see more variable compression rifle to rifle, mechbox to mechbox.

Just google a pic of a ported piston head (or go to airsoftparts.ca and look at a pic of one). Add in that you're only drilling into the front face of the piston head...and just below the o-ring...and you should have all the info you need.

Nice clean, small holes.

Or just buy a ported piston head

[shiftline]

Well the piston head is TM in mine (mp5) and its already in pieces waiting for a replacement piston, so it might be a not bad mod providing its actually worth it and wont hurt anything