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Problems with brand new hop-up


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#1 jberkom

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Posted 01 December 2008 - 07:44 PM

As you can see, I'm brand new to these boards and am also a brand new KWA owner (not new to airsoft however). I purchased an M4 tactical from ASGI about a month and a half ago with high expectations. When I first got it, I immediately noticed that adjusting the hopup didn't seem to make a significant difference in the trajectory of the bbs. If the hopup was tuned all the way down, the bbs would drop very quickly. If the hopup was tuned all the way up, they would not drop as quickly but I was still getting only about 100 feet of effective range with precision .25 bbs.

Today I dropped a brand new Prommy 407mm in with the stock bucking and stock nub. In the process I dissembled the hopup unit and checked to the best of my ability that everything looks normal. Here's my problem:

Take a look at the last few pictures on this page. http://www.airsoftre...w...=118&cat=49

You can see that the nub is creating a decent sized bump in the bucking. When I tune my hopup all the way up, I get a bump that's about half that at best and the performance is suffering. I know this gun is capable of more than I'm getting out of it. I absolutely love the rest of the gun but I don't feel like I've gotten my money's worth quite yet, at least in terms of effective range.

Am I doing something wrong? Or is this a typical problem with KWAs? Is there an easy fix?

Help!

#2 Stealthmaster14

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Posted 01 December 2008 - 08:14 PM

Possible the nub is not seated right?  Maybe try cleaning your bucking.  IDK if it is true or not, but I've heard KWAs can come with a lot of silicone in the bucking/barrel.

#3 W1CKED_TR1X

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Posted 02 December 2008 - 12:07 AM

Honestly I love my KWA gun to death, but every gun has its cons. The moment I got this gun it didn't take me long to realize that the entire bore setup wasn't that great. I ended up changing the cylinder, piston head, hop up bucking, and the inner barrel. The cylinder head and air nozzle were fine they gave a good air seal. One of the greatest problems I faced and was pretty disappointed was that the piston head came aluminum, but it wasn't ported, A BIG NEED IF YOUR LOOKING FOR ACCURATE, CONSISTENT VELOCITY AND RANGE when shooting in full auto, especially if your gun has a high cycle rate. I changed to a PDI straight cylinder, guarder hard silicon hop up bucking and bucking nub (note: the systema hop up bucking doesn't fit into the hop up unit. Learned the hard way), guarder aluminum piston head (it came ported with 10 port holes, more than perfect for accurate and consistent range and velocity when shooting full auto), and a PDI 6.05 barrel, because the KWA 6.05 barrels WERE NOT SMOOTH AT ALL. If you looked down the barrel you will see ALOT of ripples or rings whichever you prefer. After these up grades The gun was shooting just as good as if not better than a Marui M4A1. I guess they spent so much time beefing up and reinforcing EVERYTHING (which I am greatfull for btw) they skipped out on some small details that make an airsoft gun shoot like or shoot better than Marui's. I know this is long but I really hope it helps, because it sounds like you had one of the same problems I had when I bought my 1st KWA 6 months ago.

Edited by W1CKED_TR1X, 02 December 2008 - 12:10 AM.


#4 Shmoogly3

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Posted 02 December 2008 - 06:58 AM

Take your inner barrel out of your hop up chamber and then take off the arm so you can access your hop up nub. To do this you will need to pull all of the metal rings off to pull all of the gears off. After you take the arm off, see if the little nub is still there, if it is than make sure that when you put the arm in the bucking is placed into the little arc of the arm. The last thing you should check is your bucking. On your hop up bucking there is a little bump which needs to be placed on top of the hole in your inner barrel. When you engage your hop up the arm pushes down on the nub which also pushes down on your bucking. When it's pushing down on your bucking it needs to be pushing on that bump or else you won't get enough back spin.

#5 jberkom

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Posted 02 December 2008 - 12:07 PM

Thanks for the suggestions, guys. I messed around with the seating of the nub today and am getting some better results now. But I may have created something of a problem. The hop-up is basically not adjustable anymore, after reseating the bucking and the nub, i.e. the amount of backspin on the bb stays the same regardless of whether hopup bar is pressure on or pressure off. The bump on the bucking is protruding through the slot in the barrel more than it was before but it seems to be fixed in position. The position of the hopup bar doesn't affect it.

Any other ideas? I feel like I'm missing something here. The performance on the gun has improved but I don't like the idea that I can't adjust my hopup without taking the gun apart. Would a different bucking/nub combo work better with the Prommy barrel? Or am I just screwing up on my assembly of the hopup unit? (I've done this 4 separate times now and can't seem to get it quite right)

#6 vic_man4

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Posted 02 December 2008 - 05:35 PM

View Postjberkom, on Dec 2 2008, 12:07 PM, said:

Thanks for the suggestions, guys. I messed around with the seating of the nub today and am getting some better results now. But I may have created something of a problem. The hop-up is basically not adjustable anymore, after reseating the bucking and the nub, i.e. the amount of backspin on the bb stays the same regardless of whether hopup bar is pressure on or pressure off. The bump on the bucking is protruding through the slot in the barrel more than it was before but it seems to be fixed in position. The position of the hopup bar doesn't affect it.

Any other ideas? I feel like I'm missing something here. The performance on the gun has improved but I don't like the idea that I can't adjust my hopup without taking the gun apart. Would a different bucking/nub combo work better with the Prommy barrel? Or am I just screwing up on my assembly of the hopup unit? (I've done this 4 separate times now and can't seem to get it quite right)

Hop-up units are pretty straight foward, disasemble it once more and put it together very carefully, you might have forgot the little spring that returns the arm to its normal position, that would greatly effect your hop-up's adjustibility.

#7 Stealthmaster14

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Posted 02 December 2008 - 06:19 PM

View Postvic_man4, on Dec 2 2008, 06:35 PM, said:

Hop-up units are pretty straight foward, disasemble it once more and put it together very carefully, you might have forgot the little spring that returns the arm to its normal position, that would greatly effect your hop-up's adjustibility.

If that doesn't fix it, your unit just might be defective.  If it is, rather than buying another KWA unit, I suggest you get a TM hop up unit and swap out the air nozzle for a TM one also.  Then you can use whatever barrel/bucking you want.

#8 Lt. Tony

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Posted 02 December 2008 - 08:24 PM

I couldn't find a TM air nozzle would a guarder one work? and what will a guarder ported head do for my gun?

#9 Stealthmaster14

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Posted 02 December 2008 - 08:45 PM

According to KWA, if you mess with the compression parts, (other than the nozzle and hop up) you can upset the "balance."  

The guarder nozzle should work fine, but I think I TM nozzle would work better with a TM hop up if you can find one, but since you can't, it should work fine.  Talk to Allizard, he replaced the KWA one with a TM unit.  Dr. Kajita or something like that did the same also.

#10 Guest_allizard_*

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Posted 03 December 2008 - 12:40 AM

View PostStealthmaster14, on Dec 2 2008, 08:45 PM, said:

According to KWA, if you mess with the compression parts, (other than the nozzle and hop up) you can upset the "balance."  

The guarder nozzle should work fine, but I think I TM nozzle would work better with a TM hop up if you can find one, but since you can't, it should work fine.  Talk to Allizard, he replaced the KWA one with a TM unit.  Dr. Kajita or something like that did the same also.

Something probably not put back together properly.  Adjusting the hopup dial should be pretty easy to turn.   Take it out and try again.  

I think the better word for "upset the balance" should be "changing the dynamic" of the gun.  Last week we have done some testing on the STOCK non-ported piston head and result really surprise me and now I suspect it has something has to do with the stock nozzle design.   so yeah, if you change the nozzle just to fit the TM hopup up you are going affect the FPS result.

#11 W1CKED_TR1X

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Posted 03 December 2008 - 01:54 AM

View PostLt. Tony, on Dec 2 2008, 06:24 PM, said:

I couldn't find a TM air nozzle would a guarder one work? and what will a guarder ported head do for my gun?

Basically what I found out is. If you are going to change the air nozzle to a Marui upgraded one, you will have to change the entire hop up unit to a Marui, which cost about $25. In my opinion KWA got the cylinder head, air nozzle, and hop up unit just right. But it is probably the only part of its set up that can't mix with Marui parts. For the air nozzle, cylinder head, and hop up unit, you can only have them all KWA or all Marui otherwise you are going to get a very bad air seal. You can't have lets say the KWA cylinder head, prometheus air nozzle, and KWA hop up or any other mixed set up like that. If I were you, just keep the KWA cylinder head, air nozzle, and hop up unit. Their quite good, I honestly wouldn't see any difference if you switched it up to a Marui set up. The Guarder ported piston head is also compatible with the KWA piston, and it works like a charm. Very accurate, consistent range and velocity in high speed full auto. Hope this helps.

Edited by W1CKED_TR1X, 03 December 2008 - 01:57 AM.


#12 Shmoogly3

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Posted 03 December 2008 - 06:46 AM

when you turn the hop up gear does the arm move, if it is not moving then you need to tighten the screw to the main gear in more so it catches and spins the other little gears. If this is not the case than I would redo the barrel and bucking, make sure that bump on the bucking is aligned perfectly in the hole of the barrel and the main thing is the alignment of the barrel in the hop up unit. When I got my first airsoft gun and tried putting in my prommy I had alot of trouble. I knew how to do it, but there's a certain touch or comfortableness you need to be able to bet it right. I went through 2 different buckings before I was able to get it in nicely. Long story short, you should get some more practice with a hop up unit. Buy a couple of buckings and practice over and over until you get that touch! Don't get a new hop up unit, kwa's hop up unit is really good and I seriously doubt that it's defective, keep working with it. Trust me you'll find the solution. Also before you work on it anymore I highly suggest you get a couple of extra buckings, preferably systema(it's a good all around bucking).

Edited by Shmoogly3, 03 December 2008 - 06:51 AM.


#13 jberkom

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Posted 03 December 2008 - 10:23 AM

View PostShmoogly3, on Dec 3 2008, 06:46 AM, said:

when you turn the hop up gear does the arm move, if it is not moving then you need to tighten the screw to the main gear in more so it catches and spins the other little gears. If this is not the case than I would redo the barrel and bucking, make sure that bump on the bucking is aligned perfectly in the hole of the barrel and the main thing is the alignment of the barrel in the hop up unit. When I got my first airsoft gun and tried putting in my prommy I had alot of trouble. I knew how to do it, but there's a certain touch or comfortableness you need to be able to bet it right. I went through 2 different buckings before I was able to get it in nicely. Long story short, you should get some more practice with a hop up unit. Buy a couple of buckings and practice over and over until you get that touch! Don't get a new hop up unit, kwa's hop up unit is really good and I seriously doubt that it's defective, keep working with it. Trust me you'll find the solution. Also before you work on it anymore I highly suggest you get a couple of extra buckings, preferably systema(it's a good all around bucking).

When I turn the hopup gear the arm moves but that doesn't affect the amount of pressure placed on the bump in the bucking, i.e. it doesn't make any difference it the hopup is all the way on or off, it's still the same amount of backspin. I'm going to try to dissemble and reassemble again and see if I can get it right. I am planning on ordering a systema bucking and H-nub though I've read the systema bucking is fairly difficult to install in the KWA hopup unit? How was the installation on yours?

#14 jberkom

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Posted 03 December 2008 - 01:17 PM

OK, so I have the hopup unit apart right now. I've installed the bucking on the barrel and verified that the hole in the barrel is aligned with the bump on the bucking. When I seat the nub on the arm in the U-shaped holder and insert the arm into the hopup unit, no matter how much I press the arm in, the bump on the bucking will NOT extend through the hole in the barrel. In other words, the nub is pressing on the bucking, and the bucking is responding correctly to the pressure, but it's almost like the bump isn't big enough to reach through the hole in the barrel to apply pressure to the BB. The only way I can apply enough pressure is to seat the nub vertically on the arm so the end of it is pressing on the bucking. This doesn't seem like a good solution. Based on this description, am I still doing something wrong, or do I just have a crappy bucking?

Edited by jberkom, 03 December 2008 - 02:58 PM.


#15 Lt. Tony

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Posted 03 December 2008 - 02:54 PM

Sorry to thread hack. So what your saying is that It's better to keep the OEM Air nozzle, Hop-unit, and Cylinder head then to change them out Ok cool now what about the piston head. Is it better to keep it the OEM Piston or switch it out? Will switching out my piston head "change the dynamics of my gun? Also what bucking is better the Systema one or the clear guarder one?and as far as the guy with the hop up problems try to get a new nub it may seem that the stock nub is screwed up. Try those echo1 nub I use one and it makes my gun alot more accurate.

Edited by Lt. Tony, 03 December 2008 - 03:01 PM.


#16 Guest_allizard_*

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Posted 03 December 2008 - 03:23 PM

View Postjberkom, on Dec 3 2008, 01:17 PM, said:

In other words, the nub is pressing on the bucking, and the bucking is responding correctly to the pressure, but it's almost like the bump isn't big enough to reach through the hole in the barrel to apply pressure to the BB.

Inspect the bucking closely and look inside and check if the bump is missing or worn out.  I have seen 2 cases that the stock bucking is missing the bump inside.  So check it out and let me know.

#17 W1CKED_TR1X

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Posted 03 December 2008 - 10:22 PM

View PostLt. Tony, on Dec 3 2008, 12:54 PM, said:

Sorry to thread hack. So what your saying is that It's better to keep the OEM Air nozzle, Hop-unit, and Cylinder head then to change them out Ok cool now what about the piston head. Is it better to keep it the OEM Piston or switch it out? Will switching out my piston head "change the dynamics of my gun? Also what bucking is better the Systema one or the clear guarder one?and as far as the guy with the hop up problems try to get a new nub it may seem that the stock nub is screwed up. Try those echo1 nub I use one and it makes my gun alot more accurate.
Yup just keep the stock cylinder head, air nozzle, and hop up unit, unless something goes really wrong with them to the point where you have no choice. Then switch over to like a guarder double o-ring cylinder head, prometheus air nozzle, and Marui M4 hop up unit. Just to warn you. The systema hop up unit is a very tight fit in the KWA hop up, plus I get better results with the guarder buckings anyway.
If you are going to change the cylinder head unit, I really recommend the guarder or modify cylinder head, because it consists of a double o-ring seal.
Posted Image
No room for air leaks at all.
And I really have no favorite air nozzle, their all the same in my opinion and honestly think their differences in performance are so marginal it almost makes no difference. As for the piston needing to be changed with the guarder piston head.....nahhh the piston is pretty tolerant, I'd say its reliable up to a SP130 spring. I shot through around 15K shots with a SP140 spring before the stock piston shredded. So to keep it safe and reliable I'd say SP130. And as for the change in dynamics. Nope switching out to the guarder piston head can do nothing but help the gun, and because its ported, like I said before you'll get more accuracy, consistent velocity and range in full auto.

Edit by Allizard

Edited by allizard, 03 December 2008 - 10:54 PM.


#18 Guest_allizard_*

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Posted 03 December 2008 - 10:51 PM

I'm sorry I have to stop you posting this recommendation.   While it's seems like a normal upgrade, it is not advisable to match metal piston head with metal cylinder head.  You do NOT want to smash metal to metal while only less than a mm of rubber padding in between.  There is not enough padding to absorb the vibration and will most likely damage the shell.   This is exactly what I call "Changing the dynamics of the gun"  

Remember this... everything work in sync for a reason.  

The KWA hopup unit match the special nozzle, the nozzle also work with NON-ported metal piston head.  The non-ported metal piston head also work conjunction with the polycarb cylinder head.  Our cylinder head is specially design to absorb metal impact with a thick padding.  The outer diameter of the cylinder head also match the cylinder perfectly with tight seal.  "Double O-ring" according to our engineers are not necessary at all and it's been proven in the test lab.

Take closer look at our nozzle, besides the extra ridge on top, do you notice anything else is different compare to a standard nozzle?  Try put a BB's on top and see.

Just a week ago we spend a whole day testing full auto FPS consistency between Ported piston head vs. our stock piston head.  Our finding even surprise me.  KWA engineers surely have methods behind it's madness.

You want a better BB flight path.  change the inner barrel and replace the nub with a H nub for now.

#19 Lt. Tony

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Posted 03 December 2008 - 11:06 PM

View Postallizard, on Dec 4 2008, 01:51 AM, said:

Remember this... everything work in sync for a reason.  

The KWA hopup unit match the special nozzle, the nozzle also work with NON-ported metal piston head.  The non-ported metal piston head also work conjunction with the polycarb cylinder head.  Our cylinder head is specially design to absorb metal impact with a thick padding.  The outer diameter of the cylinder head also match the cylinder perfectly with tight seal.  "Double O-ring" according to our engineers are not necessary at all and it's been proven in the test lab.

Take closer look at our nozzle, besides the extra ridge on top, do you notice anything else is different compare to a standard nozzle?  Try put a BB's on top and see.

Just a week ago we spend a whole day testing full auto FPS consistency between Ported piston head vs. our stock piston head.  Our finding even surprise me.  KWA engineers surely have methods behind it's madness.

You want a better BB flight path.  change the inner barrel and replace the nub with a H nub for now.

Okay I'll take your suggestion. I'm going tp leave everything stock, and just change out the Bucking. I already a Promy inner barrel, and Echo1 nub I'm going to get a clear guarder hop-up bucking, and use that/ hopefully that will get me the accuracy I want. Thanks for the help.

#20 jberkom

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Posted 04 December 2008 - 08:12 AM

View Postallizard, on Dec 3 2008, 03:23 PM, said:

Inspect the bucking closely and look inside and check if the bump is missing or worn out.  I have seen 2 cases that the stock bucking is missing the bump inside.  So check it out and let me know.

The bump is pretty low-profile, it actually appears to be concave. Not sure if this is the design or not? In any case it's not prominent and is somewhat difficult to see even when the bucking is removed completely. What do you think?




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