I always have the issue of loosing screws when on a build and looking everywhere then finding them on the grip.
Or I’ll have the motor sitting there and put something down, like a screwdriver, too close and everything just goes spastic.
Yep, they’ve got some grab alright. 
Nice motors though… always a snappy trigger with them. 
The beauty of High Torque VS. High Speed.
They might not be fast, but by christ can pull back a heavy spring in the blink of an eye without hesitation! 
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All shimmed and done…
Interestingly the aftermarket double o ring nozzle returned shite FPS, between 220 and 240.
A fast strip and check showed the alloy nozzle a good millimetre shorter than the plastic OEM JM nozzle (you’ve brought this up before @DocBob ) A quick swap out back to the JM item and it’s sitting on a consistent 280FPS with SHS 18:1 gears, a 7.5 IB and an M90 spring.
Snappy trigger with the Chi Hai red motor, soooo lightweight (I removed the slugs of rebar), and super accurate when hopped with that sweetspot FPS.
Might change out the IB to a 7.3 at a later date for some more FPS but tbh I’m really happy with it where it is. Oh, and I took the opportunity to chunk out the battery compartment in the stock to take a half brick 3S lipo… stock’s retained full functionality.
All I have to figure out now is how to stop the janky front sight from jiggling about when it’s in it’s folded position and it’ll be one of my favourite blasters. Very annoying, that…
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Awesome results mate
Looking good and running sweet is certainly a good feeling when all the bits and pieces finally all come together!
Bit sad that the good old Rebar got the flick, it took quite a lot of recycled dog food cans to add those awesome chunks
Could always bin the stock sites and get some nice solid alloy picatinny mounted low profile units to save the annoyance once and for all
Ah, but then it’d be that little bit less SCAR-like.
True, I certainly imagined that you definitely prefer the proper model sites over aftermarket ones…… yet there should be some better quality SCAR sights available out there somewhere
Short nozzle tends to be for CYMAs
Probably… the cyl head and nozzle were packaged “Gen 8” but you know how inaccurate packaging for blaster parts can be. 
I actually thought it looked a bit short in the bag… but what the hell, it’s only screws. Ya gotta try these things.
There are, Doc… but only in 'Murica
Don’t let that stop you mate!
That’s where I got a heap of real steel accessories
Here we go again with me giving away trade secrets and rambling on like a madman 
Does anyone here actually do the water immersion break in procedures on their motors?
I only know of this from my experience waaaaayyy back when I was building custom RC Race Cars back in the early 1980’s.
Doing a proper water motor break in procedure was something that put your work/knowledge/reputation above anyone else in the hobby when it came to getting wins on the tracks with high end built RC competition racing cars.
I seriously only ever done this with maybe 3-4 of my own personal blasters, and never bothered spending that amount of time and effort on any of my customers blasters, because in reality, it wasn’t really viable as to the long term effects of such treatment.
Gelblasters simply cycle a piston in short bursts, whereas high speed RC Race Cars/Boats/Planes etc require full power, full revs and highest performance out of the motor 100% of the time.
To do the same water break in methods on a Gelblaster motor is nowhere near as important as the other hobbies mentioned for continuous high RPM use……… but the big advantage of performing this exercise was that it would increase the torque output of even a stock gelblaster motor by about 30% over standard! 
Give the same treatment to a ChiHai rare earth magnet Red Motor……. and then they were pretty much indestructible and reliable for being able to pull back a bloody M250 spring if you really wanted to go that stupid!
Edit to add that I just did a quick google search and found that this article has a good balance of information between water breaking motors and opinions about why people don’t do this anymore
https://www.rctech.net/forum/electric-road/1010108-breaking-brushed-motor-wet-dry.html
https://www.rctech.net/forum/electric-road/1010108-breaking-brushed-motor-wet-dry-2.html
How is the cyma mp5? Is it equivalent to the famous $80 M4?. 460motor, nylon gears and box I’m guessing, i might grab one as a mod tester
Pretty decent and much the same as most other models from what I’ve heard about them, so nothing to lose in giving one a try
BING feng SCAR H MK17 on the bench today for some boxing day blaster madness…
Gearbox nicely shimmed and greased…
Interestingly this must be a later version, the earlier BF gearboxes didn’t have quick change piston spring access.
But the OEM spring… it’s the shortest one I’ve pulled out of any AEG. I was going to swap it out for a standard M90 but I believe when BF redesigned the gearbox shell they did a half arsed job of it… the spring retainer’s a bit janky and with the extra length it springs downwards and rubs on the metal gears, so the stock one’s going back in.
It was hitting 270 on the chrono pre upgrade anyway, hopefully with the alloy double o ring nozzle and green piston o ring it should chrono higher. BF spring on the right for comparison to standard M90 spring.
Took the opportunity to take out the fire select levers and the bolt release, ripped off the horrible BF paint and refinished with some nicer matt black.
While I was in there, I also disabled the ambi feature for the fire select… a really piss poor arrangement with so much play it was impossible to synchronise the detent pins and it felt so vague on operation. I figured one very functional select lever over two shitty ones is an easy choice to make.
I also pulled the rear stock apart, gutted it and made storage similar to a JM SCAR V2 for a decent lipo instead of the OEM arrangement which only provided for a tiny lipo. I’ve lost the ability to adjust the stock but it’s set to a position that suits me and is now solid as a rock… small trade off again for practicality and useability. Accessed by removing the adjustable cheek riser.
When this sucker’s all back together it should be decent, I’d put it up there as better than the nylon bodied CYMA SCARs for quality.
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Thanks for sharing this, shows how much fun many of us are missing out from in this hobby
It’s looking great and sounds like it will be very comfortable, reliable and enjoyable to use after all of your modifications and improvements.
Spring Retainer Tilt:
Another awesome little design detail that will make or break any decent blaster build/design, and is a great subject for another one of my long rants
Rant away, Doc… let me start the ball rolling…
When @LowGuido reviewed these SCARS a long time ago there were a lot of design flaws, but hey… Bing Feng.
The box LowGuido tore down was definitely a litle different to the box I just worked on… his had no quick change spring retainer, mine did. But it seems those talented designers decided they’d just reworked their shell moulds without too much effort and have actually made it worse.
What you get now is a VERY thin rear wall, poorly defined lug chanels and no way for the retainer to locate securely other than by those two lugs. Anything stronger than the short spring in it now and the spring throws all it’s forces downwards and into the gearset, which is probably why the spring’s so short out of the factory…
I did replace the pissy spring retainer with a beefier version, but seeing as how it’s got no way to seat squarely anyway it makes no difference, the spring still tilts.
The other scary design feature is an aperture, maybe a weird arse inspection window, moulded into the shell right below the location of the bevel gear bush holes. So you effectively lose about 25% of your locating hole… which, to me, is a huge design flaw. Just all up lazy Chinese engineering, but I guess Bing Feng are known more as toy makers than anything else so I guess it’s to be expected.
The only things about this particular V2 style box that’s really any different is the racked fire select plate for ambi and the nozzle for the proprietry t piece. I’ve disabled that woeful ambi anyway, so I’m seriously considering stripping it again, throwing the metal gears into a nylon CYMA V2 box and swapping out the selector plate and nozzle for the BF items.
Strangely, I do like the overall build quality of this SCAR… even the colour scheme, which at first glance looks incredibly wrong, is actually spot on identical to the real steel SCAR H MK17 you can see below, photo from the official FN Herstal website.
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Great information and has jogged my cloudy old memory a bit further
I remember the cries of “but the colours are all janked up” when these were first released, but obviously comments from people who didn’t have a clue what the real rifles looked like and were probably used to just straightforward black or single colour tan blasters that were commonplace.
I do remember watching a few videos on their design and construction, and the lack of a quick change spring retainer has been the bane of many gearbox builders who always struggle reassembling them with the main spring locked inside
Was a common mod to ditch the original gearbox and replace with versions that had spring retainers to make life easier, but those gearboxes also had very bad designs and performance issues as well……… which is exactly what you have run into and can see why they were fitted with shorter weaker springs 
Horizontal pegged retainers all have a major issue with tilting down and wreaking havoc on not only hitting the gear set, but I’ve seen even worse!
Another reason why I didn’t like some unequal spring design, that had their lightest windings directly in line with the tapered end of the spring retainer.
I had a couple of gearboxes destroy themselves when the retainer tilted down, had the tapered end actually pushed into and through the bottom spring windings, and then the whole lot caught on the back bottom edge of the piston as it was being driven backwards
Obviously piston locks up hard and solid with the spring coils and retainer jammed into the rear of the whole lot, and the motor/gears are already in full flight cranking everything rearward……. yeah, lots of things go crash/boom/bang and little pieces are created in a big hurry!
Some aftermarket early gearboxes I used still ran standard 2 lug retainers, but the smart designers rotated the lug locks to run vertically in the back of the gearbox, not horizontally, which were much sturdier considering that the retainer/spring flex was limited to a side to side motion, not upward or downward within the gearbox.
Naturally the spring/retainer is contained very well from side to side movement inside the gearbox, compared with the large open space found above the gear set which allows the spring to enter into.
This retainer tilt issue was best “bush mechanic” fixed by fitting an alloy 2 lug retainer with the threaded rears, which were used in blasters that ran bolted on buffer tubes.
(EDIT: Just noticed that you have the ultra crappy design box/retainer that has those jokingly thin/narrow lugs as well!
You hit the jackpot being inflicted with those bloody things 
But not is all lost, as to run the modified alloy retainers I mention, their larger/thicker lugs can be easily filed down to size to allow them to be used in these types of gearboxes.)
The issue with models like the SCAR/ACR/UMP45/AK/MP5’s etc etc and anything else that didn’t run AR/HK style bolt on buffer tubes is that none of them had threaded spring retainers and relied purely upon the 2 lug design to maintain spring/retainer stability. 
The bolt on buffer tubes provided very solid and stable support for keeping their spring retainers in perfect alignment in comparison to those without.
So would fit bolt on type retainers to the gearboxes that didn’t have them, and then allowed to run a large washer and bolt from the back of the gearbox and into the retainer to firmly hold them in place and fix the retainer tilting problem.
It might take a little bit of fiddling to get the exact right size/number of washers sorted, as well as the bolt length, plus sometimes a bit of dremel work at the back of the receiver for clearance in some occasions, but the results were definitely worth it to keep the gearbox operating smoothly and keep them in one piece!
The next greatest invention might have been from CYMA, or one of the other reputable manufacturers, who bought out 4 lug spring retainers, that were also offset 45° from vertical once inserted and locked into place, which were extremely stable and stronger locking/retaining capabilities.
I’m very rusty on specifics memory wise, especially after so many years and hundreds of different gearbox builds/brands/models/designs as to what was what, but all this stuff is still handy knowledge for things to look out for when looking for parts and building different boxes.
Oh…… yeah…… and why does that scope look backwards?