Misery

A thing to watch out for is using agressive Active Braking

with some motors like SHS, G&G type cans/end-bells

Something to do with a mildrisk of shorting from two allen bolts into lockring under end-bell

Pete @ak2m4 does metion certain motors don't like agressive AB on Titans etc...

and being now the 621 has the Perun Optical in there...

Then be careful perhaps at using high levels of AB

TBH - you could get the SHS/RA with vented can

and if it goes a bit funny then shove the motor in 516

and then 13:1 in the 621 will still help

the 621 motor is probably a little bit better than the 516 one

the really cheap 516 Cyma motor is a 27tpa but really chucked together by a 3yr old - yes really a 3yr old

The Grey Cyma 27tpa, has no bearing in motor tower/shaft

the windings are crimped on and then somebody shot their load over the commutator - coz their is white rock hard heat resistant glue all over it - different to blue/green heat cement to hold winding in place on armature

presume to "balance" the mtor - nah, don't look like it carefully affixed - just splodged on at random where winding is crimped to commutator - it's fucking rock hard so forget ever trying to rewind this armature

Now some of the higher end Cyma's use a chrome/silver motor that "might" be say 22tpa and stronger magnets - in higher guns even perhaps weak neodym or stronger ferrite perhaps.

But certainly seems to perform a bit better in Cyma's high speed 13:1 Short Stroked HS G36's etc...

So you might get better performance just by using the 13:1's in 621 without needing the SHS/RA motor

But you could still grab one to try and if it plays up with Perun on AB

Then keep Cyma motor in 621 now with 13:1's

& chuck the SHS/RA in the 516 for added zest on 18:1's

Thing is atm, a number of bits are getting thinner on the ground

in stock or at reasonable prices whilst this import malarky begins to settle down a little

So some bits like motors from China might be limited availability for a little while longer & people like Pete have few options in stock atm

Now personally I think the specs of the RA vented 16tpa is not quite correct...

https://www.ak2m4.co.uk/internal-parts/motors-parts/rocket-high-torque-motor-long

See if that was 16tpa then it should be a bit higher on rpm on 8.4v at say 28k

and maybe the amp draw a bit higher than 3.5a unloaded

as the true SHS hits 29k at 4.8a

now these motor specs/performance do vary quite a bit

and some of the tests may have been done on one from a batch

and different magnet strengths, wire thickness SWG etc...

Plus China sweatshops revise stuff all the time

(quality can vary hence the term: Chinese lottery)

Personally I think the motor is perhaps somewhere like a 18tpa

at say aprox 25k rpm but could be way way off with my gut feeling about the vented RA

However limited choices atm, and if issues arose

then you could just chuck it in 516 I guess

if it was say a 24k/25k motor it should be OK for the 621

but if AB issues arose then no biggy to chuck in 516

& use the silver/chrome 621 motor on 13:1's

both guns then get a bit more snap anyway

if i use precocking feature on the perun then it negates the active breaking function so should be fine on that side of things

yeah the magnets in the 621 motor are strong as feck if im honest easily 5-6 x stronger than the 516's motor

i spoke to pete about the motor as was originaly going to get the shs one off his site but it was sold out in his words these are a smidge better than the shs ones

yeah man alwasy have the other one to throw it in if issues arrise

Yeah thought the chrome/silver 621 motor

"should" be a bit better than the 516 cheapo one

(tbh couldn't be any cheaper/worse than the 516 motor)

Only manufacturers do NOT ALWAYS fit the expected better

components as the gun/model's price tag increases

(usually this is true - though never always assume it will be)

Good to know it is a stronger neodym motor in there though

SHS is a good 28~30k motor

the RA seems (according to specs) to draw less amps

in line with being a 24k motor,

which is a good thing on 13:1 gears

(as said I'm slightly sceptical on specs if it really is a 16tpa

like can might say - more like 18tpa but who knows in the end)

but either motor combo will be an improvement

and the 516 gets a bit more zest either way

bit of work doing both guns

but I concur that it will offer a sensible outcome

where both guns benefit from it

and as said HOPEFULLY this upgrade malarky will reach a satisfying conclusion where both guns are sorted for a good while