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150 Spring FPS problem


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#1 KDROnslott

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Posted 06 February 2014 - 04:02 PM

First post!

Hey guys, I'm having problems upgrading my SR-12 to a DMR. I'm not getting the FPS readings i should be getting. My goal is around 550 (the limit at my field). I'm using an 11.1v 2500mAH 20c LiPo.

Currently installed:
150 spring
Alimunum piston
KWA Stock piston head
Double o-ring cylinder head
Type 0 cylinder
Helical high torque gear set
JBU High Torque motor (which I've had in the gun since I bought it).

**After doing a compression test I found that the air nozzle was leaking air profusely, so I installed a Modify air seal nozzle which is in the gun right now as well**

What I've tried:
- 150 spring with aluminum piston and aluminum ported piston head, both with type 1 and type 0
-This gave me about 440 fps with the type 0
- 150 spring with aluminum piston and KWA stock piston head, both with type 1 and typ1 0
-This gave me about 410 fps

What I used to have installed (this was my 410 setup after my gun was shooting only 370 after about a year and a half of use):
Chopped 130 spring
JBU Metal tooth piston
JBU Ported plastic cylinder head
Stock gears

#2 hellcat

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Posted 06 February 2014 - 04:22 PM

my guess would be a air leak at nozzle/bucking seal. Try original cylinder head and nozzle.

#3 vanevery

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Posted 06 February 2014 - 06:18 PM

Cylinder Head and Air Nozzle. This is your problem. Go with a stock KWA Cylinder Head and Air Nozzle and that will solve your problems. Being that your gun has some miles on it now, new parts in this regard would completely solve your problem.

#4 KDROnslott

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Posted 06 February 2014 - 07:27 PM

Update: I've reverted back to the stock cylinder head and stock nozzle. I'm still using the type 0 cylinder, aluminum piston, and stock KWA piston head. With this setup I'm getting around 480 FPS with .20s. Still very far from where I should be.

#5 vanevery

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Posted 06 February 2014 - 08:16 PM

What brand m150 are you using?
Did you install a new Danco #14 O-ring?
What Bucking are you using?
Is your Hop-up turned all the way off when chrono testing?

Edited by vanevery, 07 February 2014 - 02:34 PM.


#6 iWar

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Posted 07 February 2014 - 12:43 PM

Your not that far off from where an M150 should put you... a M150 should put you at 500-520 or so... as mention above put new O ring and make sure you stretch it properly... if you have not done that it should fix your problem, but wont get you to 550 fps... To get to 550 you should be using a M160 with 6.01...

#7 KDROnslott

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Posted 08 February 2014 - 08:53 AM

 vanevery, on 06 February 2014 - 08:16 PM, said:

What brand m150 are you using?
Did you install a new Danco #14 O-ring?
What Bucking are you using?
Is your Hop-up turned all the way off when chrono testing?

-Modify m150
-No new o-rings are installed. Are you suggesting I replace the o-ring on my cylinder head?
-Rhop
-And yes. I actually test with a regular 2gx bucking trimmed down so there is no barrel intrusion.

 iWar, on 07 February 2014 - 12:43 PM, said:

Your not that far off from where an M150 should put you... a M150 should put you at 500-520 or so... as mention above put new O ring and make sure you stretch it properly... if you have not done that it should fix your problem, but wont get you to 550 fps... To get to 550 you should be using a M160 with 6.01...

Really? I've read in numerous places that people are getting 490 with 130 springs and that 150s should get me up to around 530-550. I don't really want to go any higher due to the fact that KWA gearboxes are rated for 150 springs. If I'm at 500 I'd be pretty satisfied, just 20 more fps to go.

One thing I noticed is that the Madify Air Seal Nozzle I got to fix my cylinder head to nozzle leak doesnt work well with my hop-up unit/bucking. It was leaking nozzle to hopup a LOT (340fps). I reverted back to the KWA nozzle (which boosted me up to 480) so theres still a leak between the cylinder head and the air nozzle. Maybe the Matrix Air Seal Nozzle would work better?

#8 vanevery

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Posted 08 February 2014 - 01:13 PM

Modify m150:
Not impossible that this spring was mislabeled or that it has quality control issues.
A new m150 spring will easily have you above 500 fps provided you have no air leaks or otherwise tolerance issues with the parts you are choosing to use.
Expect 540 fps give or take with most brand new m150 springs.

- O-ring:
I suggest a new Danco #14 O-ring for the Piston Head, not Cylinder Head.
If you are using the stock Piston Head O-ring that came with the gun, the performance will  be less. It could be worn out. Most stock Piston O-rings are just not that great even when new especially compared to a new Danco #14.

- R-hop:
Great Mod.
If it is not installed correctly or your Bucking Lips are not seated properly, you could be loosing air in this location.
If you are using your stock 2g Bucking to chrono and this Bucking is worn out, the soft rubber and thin Bucking Lips may be causing you air seal issues.

Cylinder Head:
I think your after market Cylinder Head is causing you problems.
If you can purchase a brand new KWA Cylinder Head, I think that will solve your problems.

Suggestions:
- Switch to a ported Piston Head.
- Thoroughly clean your Inner Barrel and Hop-up Unit.

Edited by vanevery, 08 February 2014 - 01:15 PM.


#9 gcw360

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Posted 08 February 2014 - 09:39 PM

 vanevery, on 08 February 2014 - 01:13 PM, said:

Modify m150:
Not impossible that this spring was mislabeled or that it has quality control issues.
A new m150 spring will easily have you above 500 fps provided you have no air leaks or otherwise tolerance issues with the parts you are choosing to use.
Expect 540 fps give or take with most brand new m150 springs.

- O-ring:
I suggest a new Danco #14 O-ring for the Piston Head, not Cylinder Head.
If you are using the stock Piston Head O-ring that came with the gun, the performance will  be less. It could be worn out. Most stock Piston O-rings are just not that great even when new especially compared to a new Danco #14.

- R-hop:
Great Mod.
If it is not installed correctly or your Bucking Lips are not seated properly, you could be loosing air in this location.
If you are using your stock 2g Bucking to chrono and this Bucking is worn out, the soft rubber and thin Bucking Lips may be causing you air seal issues.

Cylinder Head:
I think your after market Cylinder Head is causing you problems.
If you can purchase a brand new KWA Cylinder Head, I think that will solve your problems.

Suggestions:
- Switch to a ported Piston Head.
- Thoroughly clean your Inner Barrel and Hop-up Unit.
I have to agree regarding the FPS and the m150.  A Guarder SP130 will give you 509 (500++) all day long with no changes to a 2GX gearbox whatsoever....or a 1st gen KWA gearbox for that matter.  An m150 should yield a better result.  Part of the issue with changes (supposed upgrades) to a system is that most people change multiple parts making it difficult to determine where a performance issues really resides.  I would go back to stock and make changes one at a time.  A lighter piston is a given improvement usually. Piston heads, cylinder heads, and other compression part do not always improve the system regardless of what we assume they can do.

#10 iWar

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Posted 12 February 2014 - 08:02 PM

 gcw360, on 08 February 2014 - 09:39 PM, said:

I have to agree regarding the FPS and the m150.  A Guarder SP130 will give you 509 (500++) all day long with no changes to a 2GX gearbox whatsoever....or a 1st gen KWA gearbox for that matter.  An m150 should yield a better result.  Part of the issue with changes (supposed upgrades) to a system is that most people change multiple parts making it difficult to determine where a performance issues really resides.  I would go back to stock and make changes one at a time.  A lighter piston is a given improvement usually. Piston heads, cylinder heads, and other compression part do not always improve the system regardless of what we assume they can do.

An M130 will give you no where near 500 fps... I run them (G&G) in 4 out of 6 of my AEGs 440 to 450...

Guarder SP130 AEG Spring by: Guarder - Airsoft GI - the largest They claim 470 but not after its broken in...

#11 iWar

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Posted 12 February 2014 - 08:27 PM

Here is a list of FPS vs Spring... Lots of people have posted real results with many different set ups...

List of Springs vs FPS Output - Airsoft Sniper Forum

Airsoft Forum > Post up your FPS results for Springs!

Airsoft Forum > spring rating's fps

Edited by iWar, 12 February 2014 - 08:51 PM.


#12 gcw360

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Posted 13 February 2014 - 07:30 AM

Here is an old thread posted by our original Moderator, karMeister.  In it he records the FPS he received with the then new to market 2GX gearbox.  The FPS was with a very settled Guarder SP130 spring (491.7 FPS).  See post #4: http://www.kwausa.co...?showtopic=1401

The Guarder claim of 470 is very conservative (at least in a KWA) and the 509FPS I posted I indeed recorded (Guarder SP130 new) with a stock 2GX gearbox and 1G bucking.  It settled to 495FPS and I eventually took it out because it's too hot for play in NJ.

Believe me when I tell you those number came as a surprise to me, but over the years I have seen it over and over and I have learned that many times you need to go down a notch on a spring swap in many KWA systems.

#13 iWar

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Posted 13 February 2014 - 10:39 AM

I can only share what my experiences are and thats the thing about forums... Everyone has different experiences... There are so many variables down to ambient temp, atmospheric pressure, and even what type of bbs you shoot... A number of people in the links I posted prove your point, but I don't think that is the norm... It just goes to show that when you buy a new spring (or change spring) you never really know what you will get... I personally use G&G and Madbull spring in all my guns because I feel that for me their the most consistent... I have a DMR (Top Tech) with a G&G M160 with great compression and It shoots 535 fps almost every shoot... Maybe this weekend I will toss it in my SR10 and see what it shoots... There there may be a large bump in FPS... I just don't think from my experience that KDR is that far off from where he should be whit his set up...

#14 niko_gpsy

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Posted 17 February 2014 - 04:26 AM

I have a Guarder SP150 in my DMR SR12 with basically stock parts and getting a 575fps with 0.20g bb's.  One issue that I have encountered is a blow-by scenario where with a very heavy spring air would leak around the cylinder and bucking in the hopup.  A tighter fitting G&G green bucking fixed the problem up to a degree.  Unless I go with a gasket seal mod on the cylinder head 575fps seems to be the best that I can get out of my DMR.  Also check that the sorbo pad on the cylinder head hasn't come off the cylinder head and is stuck to the piston head.  I had to glue mine down. lol




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