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KM4 Commando upgrade


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#1 Pete

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Posted 07 October 2013 - 05:58 PM

Hi folks,

Thanks for such a great forum for KWAs!

My objective is to achieve about 25-28 rps.
The gun internals are stock 2GX except for:
I have added a 407mm Angel Custom 6.01 tbb.
I swapped out the CQB cylinder to the stock KM4 larger volume cylinder, now getting about 400 fps (with 0.2 bbs, stock M120 spring).
I added a 11.1v 1800mah 15C lipo, which upped the rof from 17 to 20 rps (was using a 9.6v 1600mah Nimh).

I have a Chimera mosfet on the way, but I am thinking I will need a bit more in the way of mods to get 25-28 rps.

What would be a good route: a different motor, different gearset, both, or other?

Appreciate your inputs and recommended parts.

Cheers,
Pete

#2 Chuck S

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Posted 08 October 2013 - 02:51 AM

With a stock motor a higher voltage is what gets you a faster cyclic rate.  A bigger battery (higher C-reating) will have less voltage drop spinning the motor and should keep the motor running faster.  But I think you're going have to replace the motor to get the speeds you're seeking.

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#3 Pete

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Posted 08 October 2013 - 05:34 AM

Thanks Chuck.

I am considering a Lonex, A1, A2, or A3. Not really sure which one is best in my application.
Don't have much room in the stock for a better battery, I think?

#4 Pete

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Posted 10 October 2013 - 04:53 AM

Picked up the Lonex A1.
I'll report back how my rof changed compared the the stock motor (21 rps).

Cheers
Pete

#5 gcw360

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Posted 11 October 2013 - 04:09 PM

View PostPete, on 10 October 2013 - 04:53 AM, said:

Picked up the Lonex A1.
I'll report back how my rof changed compared the the stock motor (21 rps).

Cheers
Pete
There won't be any comparison.....the Lonex should smash 21 RPS!!!  And, please don't get me wrong.  I like the KWA motors as a stock motor.  But a Lonex A! is a brute!

#6 Pete

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Posted 11 October 2013 - 08:13 PM

Yes, that's what I'm hoping for!
Hopefully my modest lipo can feed it adequately.

#7 Pete

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Posted 12 October 2013 - 08:05 AM

Put the Lonex A1 in this morning.

Got 24 rps, up from 21 rps.

Not as big a jump as I was expecting, but gets me close to my goal.
I am using a crane stock 11.1v 1800mah 15C lipo from Evike, replaced connectors with Deans, all wiring is stock KWA.

Awaiting a Chimera mosfet, will see how that improves the rof.

Edited by Pete, 12 October 2013 - 08:05 AM.


#8 gcw360

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Posted 12 October 2013 - 08:21 AM

View PostPete, on 12 October 2013 - 08:05 AM, said:

Put the Lonex A1 in this morning.

Got 24 rps, up from 21 rps.

Not as big a jump as I was expecting, but gets me close to my goal.
I am using a crane stock 11.1v 1800mah 15C lipo from Evike, replaced connectors with Deans, all wiring is stock KWA.

Awaiting a Chimera mosfet, will see how that improves the rof.
A 15% increace is ok .  I actually expected more.  The motor may require breaking in.  How is the trigger response on comparison?

#9 Pete

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Posted 12 October 2013 - 11:42 AM

trigger response is crisp, nice

#10 gcw360

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Posted 12 October 2013 - 02:05 PM

View PostPete, on 12 October 2013 - 11:42 AM, said:

trigger response is crisp, nice
Better than stock?

#11 Pete

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Posted 12 October 2013 - 07:39 PM

Feels a bit better than with the stock motor.
How much break in might a new motor require?

#12 gcw360

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Posted 12 October 2013 - 07:58 PM

Hard to say.  See here for more info: http://www.kwausa.co...?showtopic=8164

This alone may give you a boost in ROF.  As a comparison, I am using an SHS High speed motor with a lighter piston and a KWA M130 spring.  As of today with an 11.1V 1400 mAh 15C lipo
  • 28+ RPS
  • 460+ FPS
Hope this helps.

#13 Pete

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Posted 14 October 2013 - 03:44 PM

Took the Lonex out, cleaned the brushes and commutator.
Found one screw that would not tighten with the brush wire connector under it,
so I cut it off and put the brush wire under the spring tensioner wire, as is common.
Lubed the pinion gear (forgot to when I initially installed it), adjusted the motor height.

Re-ran the chrono test and picked up 1 rps, now shooting 25rps (just meets my goal, so I'm happy).
Not bad, a 4 rps increase over stock KWA motor.

Mosfet install is next.

#14 gcw360

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Posted 14 October 2013 - 03:49 PM

View PostPete, on 14 October 2013 - 03:44 PM, said:

Took the Lonex out, cleaned the brushes and commutator.
Found one screw that would not tighten with the brush wire connector under it,
so I cut it off and put the brush wire under the spring tensioner wire, as is common.
Lubed the pinion gear (forgot to when I initially installed it), adjusted the motor height.

Re-ran the chrono test and picked up 1 rps, now shooting 25rps (just meets my goal, so I'm happy).
Not bad, a 4 rps increase over stock KWA motor.

Mosfet install is next.
I'd say that's a win.  Thank you for the feedback.

#15 Pete

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Posted 14 October 2013 - 04:00 PM

Thanks for your help!

One question, as I was backing out the motor height adjustment, the gun was getting faster, but then it started to double fire on semi.
Read up a little and a good trigger squeeze on semi and that did not happen again.

But it seemed faster with the motor looser.
Not sure what is the optimum way to adjust motor height.

Edited by Pete, 14 October 2013 - 04:37 PM.


#16 niko_gpsy

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Posted 16 October 2013 - 11:01 AM

If your motor height is in the good range, you should be able to hear a clean "pop" .  If the motor height is too high you will hear a high pitch squeal and the motor can heat up and rof slightly slow down.  This happens because your pinion gear is exerting an excessive downward (or upward) pressure against the bevel gear almost locking up that gear.

You can find many tutorial videos on youtube on this subject and I suggest you watch as many as your can handle.

#17 Pete

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Posted 17 October 2013 - 03:52 PM

Thanks. I have adjusted it.
It seems to have a fairly large good zone, but I did find the squeel zone and backed it off from there.

Edited by Pete, 17 October 2013 - 03:52 PM.


#18 Pete

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Posted 18 October 2013 - 04:58 AM

So I disassembled the gun to install the Chimera Mk II mosfet and found two teeth missing off the spur gear outer radius, missing roughly on opposite sides of the gear.

That was kind of a surprise.

Does the lipo I have and the Lonex A1 seem like too much torque for the stock gearbox/M120 spring combo?
Are these failures heard of with my setup?
Maybe I got a defective spur gear?
Should I look at stronger spur gears, which ones?

Pete

Edited by Pete, 18 October 2013 - 04:58 AM.


#19 gcw360

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Posted 18 October 2013 - 08:41 AM

Your setup should not cause that normally.  I would replace with an OEM spur gear.  That sounds to me like a brittle gear. But that's just a guess and I've not heard of it happening often.

#20 Pete

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Posted 18 October 2013 - 09:11 AM

Any thoughts on the guarder spur gear vs. the kwa?
The KWA spur gear looks like a cast part/not heat treated, but I may be wrong, the bevel gear definitely looks heat treated.
The guarder part claims to be heat treated.

Anyway, I'd be willing to put another KWA part in and hope this was a fluke.

Edited by Pete, 18 October 2013 - 09:25 AM.





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