Radio Control

Quanum QRF-400 RC BIKE (no longer available for purchase)


Specifications:                                              [goto Build Checklist]
Length: 530mm
Weight: 2349g
Motor: Team Orion-like Brushless 2840kv   (not 2100)
Wheel Front: 160mm Moto-X
Wheel Rear: 145mm Enduro
Steering Servo: Standard High-Torque
ESC: 60A Car ESC (380A Peak)
Battery:  4000mAh 3S2P 20C LiPo

My bike ready for its first ride

Now: When 2 Bikes are better than one

LiPo & ESC mounted


Some assembly is required...


Build Checklist
Rear wheel & Gyro:
  • Pull the rear tyre off and disassemble the wheel
  • Check and balance the Flywheel. If necessary, glue weight to the inside flange with CA (supplied).
  • Check spider gear arrangement for clearance between gear axel studs and the clutch plate. May be necessary to add a thin 6mm washer to create the correct clearance between the spider gear arm and the clutch plate gear.
  • If spider gears are binding on the ring gear, try swapping the 4 gears around and/or loosen/re-tighten the ring gear to find a better centre.
  • It is recommended NOT to use grease on the nylon gears as it will possibly find its way onto the throw-out clutch arms.
  • glue the rear tyre on around the bead with CA.  Keep it minimal, especially on the non-sprocket side so it can be removed for servicing the Gyro.

Go over every bolt with (non-permenent) thread lock, these specifically:

  • front wheel grub screws, under the fork guards
  • the 8 Bolts in the parallel steering links, upper and lower
  • The front mudguard/headlight panel bolts
  • The front Lexan cover mounting post
  • The top front frame bolt, as it is too short to fully engage the lock nut nylon
  • The steering rod clamps and servo arm attachment point
  • Pinion on motor
  • Motor mount bolts
  • the rear wheel adjustment grub screws after 1st run (as chain will stretch from new on first few runs)
  • any other bolt that secures into metal

Rear Shock:

  • remove the top cap and fill with oil (not supplied) Suggestions at stage would be 50 weight synthetic shock oil
  • optionally, replace with a Traxxas E-Revo 5608 shock. It has longer travel and better seals.

Pinion/Spur Gear Mesh:

  • being a nylon spur gear, set it up on the tight side, compared to 1/8 nitro truggy which has a metal spur, you should just be able to see/ feel a very small gap when rocking the Pinion/Spur gear in mesh.

Swingarm Shaft:

  • It is highly recommended that the swingarm/drive shaft is replaced with the upgraded shaft before your first run.
  • Optionally, grab the ARX540 equivelent if they are out of stock.
  • Move the spur gear and sprocket in to capture the swingarm bearings so as to remove any side movement of the swingarm.
  • Ensure the spur gear and sprocket set screws are securely loctited onto the divets on the shaft.
  • The hardened tool-grade shafts may not bend but can still be broken. It is paramount that proper chain tention is maintained at all times.

Chain Tension:

  • The stock chain is going to stretch a lot in the first few minutes of running. (I strongly recommend getting the ARX540 chain replacement as it is much stronger and less prone to jumping the sprockets and bending or breaking the drive shaft.)
  • Apply a small amount of loctite to the tentioner set screws to prevent them from moving, while allowing some movement for frequent adjustments.
  • Do not over-tighten the rear shaft end nuts as it may bind up the gyro. The set screws must be used to prevent the shaft from moving forward.
  • Run the whole drive train on the bench for 15mins or so to bed everything in before doing an actual run (which adds uneven loads)
  • Check the gyro is running smoothly after 3/4 throttle and should continue running for a while after stopping the rear wheel.
  • Continue to retention the chain but be sure to not over-tighten it. It should have about >=5mm of play in the centre of the chain. 
  • Keep an eye on it during first run as it may come loose and jump off the sprocket, causing a lockup and bend the main drive shaft.
  • Optionally, make a chain slider out of some 5mm Corflute and secure it with 2 zip ties. This helps reduce chain slap and eliminates jumping off the sprockets. It will also protect the swingarm. This is more simple than a chain guide and works quite well.
  • Optionally, make a chain guide to feed into the rear sprocket.

"Crash" Bars:

  • These need reducing in size as they dig in during normal cornering and cause more crashes than prevent. 
  • I cut about 50mm (2") off one leg of each bar and straightened the 90 deg. bend on the short side somewhat and made a gentle but constant radius bend all the way around to the other 90deg. bend.
  • then put a small 30deg. bend in the longer side about 40mm from the end.  This resulted finally after some careful shaping in a "D" shape with legs parallel and the correct distance apart to fit the bike mounts.
  • I added some 3mm corflute to provide some extra "floatation" in the soft dirt.
  • Rather than loctite the set screws, I placed tape over the screw holes to prevent them disappearing since they get removed a lot during any maintenance. Despite no loctite, I haven't had one come loose yet, possibly due to a slight spring condition setup by the bar legs.
  • Optionally get the flexible bars from AR Racing.


Apply Stickers:

  • Remove the clear protective covering before applying the stickers.


Exploded View 1  Exploded View 2  Exploded View 3

Quality ARX540 Spares fit this bike and can be sourced here:

(chain, stand)

Traxxas E-Revo 5608 shocks (for 1/10 scale trucks)

replacement shocks - use the original top cap

You can usually get these in packs of 4 and they are good value and provide for longer travel. Replace the lower nylon link with the stock metal link from the original Shock.

If not replaced the lower link will snap open under full rebound, generally during an end-over.

Alloy Steering block upgrades

I prefer the Nylon blocks so as to have a weak point to break if you run into something.

Turnigy (Hobbywing) Brushless ESC 60A w/ Reverse prog. (v2.2)

Cont. Current: 60A
Burst Current: 380A
Resistance: 0.0007ohm
Car Size: 1/10
Suggested Motor: Around 5.5T / 3650kv
Battery: 2-3 Cell Lipo / 4-9 Cell Ni-XX
BEC: 6V/ 1.5A Output
Motor Type: Sensorless Brushless
Size: 31.5*27.5*24mm
Weight: 32g

See the Manual Progamming Chart for suggested initial settings, or use the Programming Card

So far after many hours this ESC has been bullet proof. Barely gets warm with that fan.
Be sure to do the mod to connect the fan +ve (red) wire to the ESC 5volt output, 2nd pin on the right.

Optional Motor replacement: EZ-RUN Brushless Motor 13T 3000Kv

(shaft is 3.17mm and this motor is a direct replacement for the stock unit. Bit down on power though)

Optional Motor replacement: Turnigy Aerodrive 2300Kv

(shaft is 5mm so you'll need a new 15T pinion but this motor has loads more power than the stock unit)

Battery: Turnigy 4000mAh 3S2P 20-30C Lipo pack

Stock motor: fitted with a Team Orion-like ORI28173 Experience 2 brushless motor

KV (RPM/V) 2840
Input NiMH/NiCd 6-8 cells,
LiPo/LiFe 2-3 cells
Max continuous current 50A
Max peak current (10S) 70A
Resistance (mOhm) 23.00.8
No load current 1.6A
Recommended Timing 2 5
Shaft lenght 14mm
Shaft diameter 1/8 inch 3.175mm
Dimensions 46.4x36.1mm
Weight 170g


Pre-Build Photos (out of the box) for reference.


at 1/4 Scale, its a biggun!  buy one here Hobby King

Video Review


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page updated 4-July-2011

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