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Trex 600 6s-8s Scorpion 890KV Modification

October 14th, 2009 3 comments

Scorpion HK-4025 890kv - BoxI recently burnt out my Align 650L 1220KV motor on my Trex 600 and decided it was time for an upgrade (as a side note the 650L was a pretty good motor as far as Align goes it lasted over a year). One of my main goals was to allow me to initially continue to use my current configuration of 6s batteries and 100A Align speed controller. But at the same time allowing myself an upgrade path to an 8s setup once my current set of 6s batteries die (that also implies an upgrade to a high voltage speed controller).

 

Scorpion HK4025-890KVScorpion HK-4025 890kv

I finally decided on a motor, the Scorpion HK4025-890KV, which actually comes in slightly cheaper and lighter than a replacement 650L 1220KV with similar power consumption. The one main difference however is the KV rating, a difference if 330KV. The way to compensate for the lower KV was to use a larger pinion, as it turns out Mikado do a 20t pinion which fits a 5mm output shaft, which addresses the problem nicely (on the 650L 1220KV I was using a 15t pinion)

Mikado 20t Pinion

The Scorpion motor whilst shorter in length than the Align 650L is slightly wider, and the 650L was a very tight fit, hence a simple frame modification is required to get this badboy in. A small section of carbon just below the motor mount needs to be removed on both sides of the frame, nothing a couple of minutes of dremeling wont fix :)

Before Frame modificationTrex 600 Frame Mod

After Frame modificationTrex 600 Frame Mod

Once the frame has been modified the motor slides sideways into the frame easily, the next thing you will notice is the Mikado 20t pinion is so big it doesn’t clear the main gear (and if you took the main gear off it’s likely to be too tight or not fit at all).
Another small modification is needed, this time to the Align motor mount, again very simple, all that is required is the bolt holes need to be enlarged lengthwise towards the front of the model which can be done with a drill and 4mm bit. You don’t need much, I drilled one hole at the end of each bolt hole to enlarge it, which allows the motor to slide forward more on the mounting bolts.

Align motor mount after modificationTrex 600 Motor Mount Modification

Installed Mikado 20t pinion and modified Align motor mountMikado 20t Pinion Installed

All things considered this modification was very easy and other than the Mikado 20t pinion no other non Align parts are required. No one likes modifying frames but this was truely very quick and simple with the dremel and doesn’t compromise the frame at all in my opinion. Also as it turns out I came up 70g lighter which is always a bonus.

Scorpion 890kv Modification Complete

Flight testing on 6s with the Align 100A speed controller went very well, I don’t think I’ve gained or lost any flight time I’m still at 4mins hard 3D. The motor seems have good torque and be very resilient to bogging, the ESC and motor temperatures are also healthy. Overall performance with my setup is slightly above the 650L (…and I had good results with the 650L). Obviously with any 6s setup when flown aggressively will push the batteries limits in terms of heat, current draw and performance which is why in the future I will be moving towards 8s, which the Scorpion HK-4025 890kv should handle nicely.