KMX - Cobra !

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2012 - April 17


In march, i started with a thread on ES to inquire about what my options were regarding trikes...

2012 - Year of the TRIKE !

I had pretty much made up my mind on the KMX from day 1, i sent an email to a kmx dealer in Quebec and asked for a quote, even wrote my email in french to encourage a quick reply ( yeah.. i'm an impulse buyer ) ... a few days went by with no reply...

On march 16th, I got in contact with Recumpence, aka: Matt the RC guy ( RC bike ! ) ! , who happens to be a KMX dealer.. within minutes i had a reply to my email.. and by march 19 funds $$$ were sent...

2 days ago, FedEx left a notice of delivery on my door ( go figure, 10 minutes after i left for work.. grrrrr ) .. but later that night :

I was quite surprised at the size of the box, i was expecting something quite larger.... was afraid only part of the trike was in there


But, yep, it's all in there .. somehow.. terrific packing job.. +1 KMX !

I'm reminded of the micro-car with clowns that keep comming out.. 3 wheels.. a frame.. nuts, bolts, tools, .. it's all in there.....
Full color instructions/assembly manual..

3 wheels with parts partially installed, cables neatly zip tied safely into bundles, seat looks very good.... and comfy !

Frame, nicely protected in bubble wrap.

Nice bright candy orange, good welds, no flaws that i can spot yet.

8mm hex and 17mm wrench for the bolts that mount the front wheels brackets to the frame.

The box contains tools, but they are basic cheapies stamped metal that tend to round off nuts ... so i used my own !

Front wheels on, i had to hold back the urge to just get with it and stick to the instructions.. as hard as that is to the average male.. i'm a firm believer in " try it and if all else fails read the manual "... but RTFM rules in this case was observed .

Bravo kmx for not pre-installing the derailleur hanger, many bikes arrive with bent hangers, and this can be a frustrating event to a newb resulting in a derailleur into the spokes ....

Neatly bagged and tapped to the rear dropouts..


ok.. 1st gripe... minor one tho..

These are made of stiff plastic that will not give to insert the cables.. they just snap, i tried being gentle, i wiggled and rocked .. and tried my best but snap..

then i tried lube..

But no.. broke a 2nd one..
Then i got the flat file and opened up the gaps so the rest went as expected, what's going on here is that the brake and shifter cables are not the same diameter, brake cables are larger.... but the mounts are all the same size.

It's not a big deal however.. . a zip tie and a dab of hot glue will fix this. more on that later.

Seat went on easily.. so did the rear wheel and derailleur..

The chain guides however, gave me some grief, i sat there and scratched my head a while and googled, and youtube searched for video's of how this is supposed to be.. but it seems there have been various changes over the years and nowhere could i find my setup explained for dummies... the diagram in the manual shows in black and white how it should go, but not in detail enoughf or me to easily figure it out....

So, for the next guy who has to figure this out.. hopefully you find this picture.. not 100% sure if this is how it goes.. but it's how i did it.

And, finally, here we are :

Fully assembled .. but a fair bit of fine tuning to do..


Above, as you can see, the chain is too long ( meant for longest possible boom position, but i got short legs.. )

So i removed a few links, adjusted the seat to be a bit more upright.. and went for my first test ride !


Ok. so it's cold and cloudy, and windy, holiday tomorrow so work let me out early and i jumped at the opertunity to get home and go for my first test ride.. i had it built last night but it was raining and i did not want to dirty up a brand new bike on day 1 lol..

Front brakes not yet adjusted, but i got rear, so good enough for a test ride..

Seat, way comfortable, you could go all day on this thing and not have a sore ass.. hell.. i see myself going out on late night rides with a case of beer..

There are quite a few adjustments that can be made on this, steering arms can go in or out, adjust radial, but i set it up roughly good enough and kicked off...

Oh my, this is FUN !!..

I zipped around the yard getting used to the feel, it has the turning radius of a school bus, but once electrified ( and you can bet it's getting electrified shortly !! ) it will be a good thing at speed..

It gets plenty of looks, cars slow down and stare as they roll by.. people out here are not used to these machines.. and attention is of no short supply....

15 minutes of pedaling up and down my street and my legs are jello.. i predict great soreness..... more to come

April 7 , 2012

So, got the kmx back in the kitchen, I had it in the garage for a few days but it's cold out there and starting up the oil furnace means cleaning the area, plus, all my ebike parts are in the house.. so ..

I dug out a box with a used X5304, laced in a WIDE 24" rim with 10 gauge spokes, Found a 24 x 2.4 holy roller and tube

This motor originally did not have a disk brake, one got added, the axle is also modified with coarse thread and milled down at the ends..

Turns out, KMX manges to cram an 8 speed + hub + disk into a 135mm slot... mtb's with disk tend to be 150mm, surprise, surprise..

So i put the 5304 aside.. and went back to the parts room... found this !

x5305 in a 20"..

This is going back to the bad years of crystallyte, prior to milling axles properly and having spoke flanges in the right place..

Game plan for tomorrow.... unless i come up with another idea tonight.....

is to take my angle grinder and remove axle material to shift the motor to the right side by as much as the thickness of the frame and derailleur hanger, add an inside torque arm to the left side of the axle, and i'm rolling on tripple 20's !.

No rear brake, but from what you guys are telling me and my short amount of riding confirms that it's all about the front brakes anyways..

It's crude.. but between dremel, angle grinder, and bench grinder, the hack saw won out. oh what i'd give for proper tools and knowing how to use them...

But, as you can see, all you newbs out there , this can be done with the most basic tools if you take your time and think it thru...

With carefull eyeballing.. i got both sides very close to equal.. a bit of work with a flat hand file and this sucker dropped into the frame perfectly !

I slapped on a used 20" x 1.95 hookworm for the time being, i need to start using my tower of tires, it's getting tall..... i figure i'll burn this one up quickly so may as well put on a used one !

I tried spinning the axle by hand and could not budge it, weird, as i can usually spin up most hubs by hand. .. put on a wrench and it spun over but there is obvious non-expected friction going on.. this motor has all of maybe 20 minutes of use on it since new... never in rain.. soooo...

Went digging into my stash and found a NOS old school analogue clyte controller..

This is the last one from my shipment, i quit selling them, so un-reliable they were costing me more money in return shipping than they were worth, labeled as 72v but only work at up to 48v ( i blew up 80 % of the batch trying them at 72v.... but reliable at 48.. argh. )

It's ALIVE !!!..

After spinning on the bench for a minute, it's back to normal, bearings just needed a good run-in


April 12, 2012

Should be able to test ride this sucker tomorrow

i've been playing around with controller and throttle etc placement, mounting stuff to a trike is a walk in the park, loads of room to bolt and mount stuff to, I"ll be able to fit a HUGE lipo pack on this thing !!!!

This is likely going to be the first rig i can justify the use of an X5 on.. considering all i have available in my parts stash, i'm running a xlyte 4 series on my daily driver and a 9C on my e-BMX, i've had an X5302, 2, 4 and 5 on hand all these years and the chopper got the most use with a 5304 but not that much.. they are rediculously heavy for sub-5000w setups..

I can even conceive of a BMC geared motor on this as a good option, would shave 20 lbs off the machine and work just fine for the speed i am willing to go on this.


Ok, no pictures or videos yet but i have gone on my first electric trike ride !!!!!

It was not an easy, out the door i go, thing either...

After bench testing the throttle, controller and motor, i was confident it all worked.. so i plugged it up to the trike and electrical taped the bits on for a quick road run...

Plug in battery... and zip.. zilch.. nadda....

Now, this controller is an old 4 pin model throttle, the new throttles are 3 pin, ( the 4th pin is for LED throttles )

I lucked out when bench testing and plugged in the right row of pins.. but when transfering to the bike i unclipped the throttle and had to plug it back in.... ( more on this later ).

Alrigh.. so yeah.. it's now 9pm, pitch black out there.. i should be out riding but noooooo..

Fine.. get another controller from the dual speed 20 amp batch, plug that in.. with both throttle combinations.. no go..

ok.. back up stairs to the stash room.. i get a few more throttles ( I have a box of 50 you know.. ) .. still nothing.

Dig out the Lyen testing rig , original throttle and 2nd one both dead.. new un-used throttle.. works.. wtf.. ok.. fine. so i go upstairs and get a new motor ( 4013 clyte ) ..

plug that in but this time making sure to use the other combination of pins first time out and WHAMO .. we got juice !!!.

So now i'm up to my knees in parts.. shove all that over.. plug original controller and new now tested controller back to the trike.. a whole bunch more eletrical tape.. slap a 48v lipo pack on this thing and dress warm.. out i go !

Flashlight in one hand.. throttle, brake and steering with the other.. chain derails right away.. but F it. .. Y Pedal i say ! when you gots a motor !!!

aw man this is fun.... totally needs a thumb throttle.. twist is suicide on this type of steering..

Had no CA so did not dare go far on an un-tested 5ah lipo.. 72v will be plenty fast.. and 100 amps should provide donut making power...


April 14 , 2012

Ok.. so today i decided to deal with the chain issue..

The Cobra has 3 speeds in front, so with the big fat X5 on the back i really only need a single speed at the back, and that's all the room i have to spare with the centered hub and cut axle..

So after adjusting the derailleur to perfection i tried pedaling and quickly found out i had a problem on my hands, after much noggin scratching and observation, i found that the chain is not engaging the teeth on the single speed freewheel properly, at all, the chain rides high and skips at the slightest pressure on the pedals.

Well, i figure that by taking my dremel i can " massage " said freewheel into working, an hour later i have the chain kinda engaging properly but still not right, however i discover another issue, the damn thing wont ratchet as it's supposed to and just slips...

Alright.. no problem. i got a dozen of these damn cheap china no name freewheels so i cut the tape, again, disconect the motor, pop the motor off the bike. run in the house to get my freewheel tool... uhm.. yeah.. i reamed out a multi speed tool already but never did the single speed tool.. so it wont fit over the axle.. and this is one meaty tool... oh my kingdom for a lathe....

But, since this freewheel is toast to begin with, what the heck.. o'l screw driver and hammer trick.. bing bang.. off it goes..

Now, i have a really expensive Eno 18t from my RC bike project, i checked the teeth of this with the chain and it meshes perfectly !.. sweeet !.. only problem is that it has a damn 10mm shaft adapter spun on it, aluminum, jammed in there royally, spent almost an hour with my neighbor trying to get them apart.. no luck.. so this goes back in the " RC parts " bin..

I grab a new freewheel, of the cheap no name variety, but since it's not attached to the motor, i can work the teeth before installing it on the motor !.. bonus.. so 30 minutes later.. i have it almost meshing.. but still not right.... i'm not going to do this..

Tomorrow.. i hit up the bike shop for a proper freewheel.. shimano or similar.. then the motor can go back on.

Below :

No.3 is the original freewheel i havebeen messing with..
No.2 is the mess i made yesterday from a no.3
No.4 is an ACS 14t i picked up today at the local bike shop
No.1 is a no.3 that i fixed !

* The tape on 1 and 2 is just to keep dust and grindings from the insides of the units....

So after a dissapointing day yesterday not being able to resolve this.. i had to go to my nephew's 3rd birthday party across town at my sisters, so i used the RC bike to get there and on my way home i swing by the local bike shop with a piece of chain and my problem freewheel..

Here is the problem :

Below, see how high the chain rides high on the teeth.. ( the picture actually makes the problem obvious, i should have taken pictures yesterday


Here is how the chain should fit.. on an ACS claws 14 tooth..

Problem here, is that neither did i or the bike shop owner guy realize that the threaded inside of the units are not the same diameter, this will NOT fit a crystalyte threaded collar.. it's too small..

wtf... this is supposed to fit, i have no clue..


This is no.2 i mangled yesterday, trying to grind down the teeth a step at a time with no luck.... this is where i gave up

so here is the problem.....


the ACS = 2.34mm

cheap chinese 16t freewheel = 2.85mm thick !


Solution, for now, take the angle grinder and shave the thickness of the 2.85 down to 2.3x , put it in a bench vice and carefully worked it down until

Now, after all that work, i spun the modded cheap chinese fw on the hub, bolted the motor back onto the KMX, ran in the house grabbed a 48v 5ah lipo pack in a hurry and taped it to the bike..... slapped a CA on there ( thank god ) and off i went..


As soon as i got going, i noticed my 12 cell pack voltag was a curiously low 40v, should have been 50v.... but in the heat of the moment, too excited to investigate.. i throttled on with grin from ear to ear

Then it hit me.. oh crap... i picked up the wrong lipo pack..... I had a pack ready to go, ballanced and fully charged, but the other ( idential looking was right next to it with 1 cell at less than 3v !! while the other 11 were at 4v + !!!!!!

Pedaled home, see, good reason i got the pedals working as a priority !

cut it off the bike, ran into the house.. grabbed the " other " battery pack. set the previous one in the middle of the driveway far away from anything flammable, deal with that after.. strapped the fully charged pack on the bike and put on a helmet and gloves.... !

OMFG..... this is so much fun, it's even better than i expected, even with only 48v 35 amps this X5305 in a 20" rim is smoooth as silk..

I went up the road alongside 80kph traffic, a few figure 8's in the honda/ harley davidson dealership parking lot, zipped back home and up the dirt track alongside the CN rail service road .. ( BBbBbbbbBbUuuuuMMmmMMmPpPPppPP YyyYyYY ) .. but still fun !!!.. these KMX's are sturdy machines.. i weigh 185 lbs atm and got properly bounced around, will have to repeat this a few times before i declare it " tough " .. but it's certainly not flimsy,.,..

So, after all that disaster, it's a running machine ! and ready for upgrades !


April 18, 2012

Yesterday, removed disk brake, cable and lever...

Perfect spot to bolt up a monster torque arm

"*(( torque Arm : part used to prevent the axle of the motor from loosening and ripping itself out of the bike frame.. there are many ways to do this, and depending on how many watts you plan to use, they need to be thick and of strong material to do the job .. regular bicycle frames are not built with hub motors in mind. ))

Also removed rear shifter cable and lever...

I cut an old brake line short and locked the derailleur into the single speed freewheel... no more accidental shifting and loosing chainline.. and one less thing on the handle near the throttle !

Got a roll of red 3M safety reflective tape.. I needed to seal up some PSI filled polycarbonate boxes..... time to put these cells to use !

I like tape.. after messing with metal straps, hose clamps, threaded rod, etc etc etc... the right type of tape used in the proper place, works as good or better.. and takes seconds to do vs working with metal.

Cut a piece of black ABS plastic, heated and bent to match the frame angle, I will use double sided tape, and zip tie it to the frame.. then tape the 2 packs on top of this.. one is shifted to the left so that it does not interfere with the chain line, then the 2nd pack on top will be centered with the seat and secured up there somehow.. that's a tonight plan.


April 19, 2012

small update.

Bent a strip of flat aluminum bar into shape...

As simple as this S.O.B. was, it took me a few hours of staring and mangling metal before i got to this point.. i hate how i get bogged down sometimes on the simplest things.. yet some complex parts i can just fly thru... regardless.. i'm getting this done and having fun doing it !

Cha-Ching.. this 3m reflective tape lights up at night( or in this case.. with a camera flash.. )


April 21 , 2012

Finally got out today for an off-road ride, up my road, thru the traffic circle, and onto the trails i went..

No.1 .. this thing needs mud guards !!!!!! ...

Something i'm familiar with, having an old Honda 250sx trike, when the trail splits in 2 ( the typical 4 wheel vehicle pattern in trails ) you have to choose between the center wheel in the rut, or the pair.. with center in the brush....

However, when the trail opens up and all 3 wheels get good ground , this thing is an absolute riot !!!

I went over a section of boardwalk that's all messed up and really rough 2x4's all at un-even heights.. on my way up to the skate park i rolled along slowly to keep the shakes and bumps down but holy crap you really take a beating... On my way home we were fighting rain so i gave it hell ( 48v ) .. discovered that once you reach a certain speed you kinda skip some harsh bumps and skim along..

Kids at the skatepark buggered out and loved the trike.. i've shown up with the chaos, the BMX, my neighbor's 100v 9c bike.. all my machines get thumbs up but the trike gathered a crowd..

You get lots of attention on this thing.. thumbs up from everyone.. people whip out their phones and take pictures out of car windows as they slow pass lol...

I managed to pull a proper donut today ( on dry gravel/dirt ) did a full 360 with a dust clowd !!.. woot !.


April 30, 2012

This weekend, messing around in the garage, i kept going for short trips up the road, thru the construction yard.. back home.. work for a bit.. go for a ride.. got more comfortable as i put more seat time on it.

I had my first tip-over on sunday ! .. my driveway is 2 cars wide + , doing as tight a circle as i could i kept adding throttle and leaning until i reached a point with 1 wheel just off the ground for another turn then zoink.. i tipped.. being so low to the ground tho i just rolled over and back onto my feet ! ( yes.. wearing gloves !! but no helmet.. )

Aaany ways.. so this past week i've been real sick, wooping cough is going around here and everyone is sick it seems.. was my turn last week. so i'm all goofed up on cold meds.. stuffed up . ears ringing.. just kinda physically messed up but mentally ready to bike..

Anyone see the problem with this picutre ?

I disconnected both 24v 10ah packs to charge with 2 seperate soneil 5 amp chargers..

Once charged, i checked all cell voltages, 16 cells all at 3.457v , perfection ! ( No BMS, 2+years not ballancing, used at times, sitting for months .. )

I grab a red and a black that are aimed at the Cycle Analyst and hook'em up., i hear a " pop " . that familiar crackle you get when the controller powers up ( charging capacitors ) .. then i look over and see another + and - pair..

I just plug them in to complete the 48v junction between teh 2 packs.. but wait.. i heard the controller power up.... uhm... ** all this in about a 2 seconds ***... then i hear a WOOOSHHH... and a huge puff of white smoke come billowing out the side of the trike and fills the garage !!!..

snapping back to reality, i swipped at the wires thru the smoke and luckily hooked the right wire to seperate the connection, without burning myself..

the anderson housing melted off and coated the connector..

Grabbed the pedals and yanked the trike out of the garage to let the air clear..

I was sure one or more cells were going to vent, i quickly grabbed the top pack and pulled it off and away from the house..

Got the volt meter out and would you imagine.. 3.335v all cells.. and aprox 40 celcius cell temps.

in 10 minutes i had this thing apart.. Bonus for nuts and bolts packs.. they are large and bulky but easy to repair !!.. been wanting to change the stiff car audio cable for soft silicone turnigy 10 awg wire.. so made up a pair.. bolted back on .. re-charged the pack , took 5 minutes to top it off.. checking cell voltages all 3.45x at green light

I noticed this PRIOR to the battery incident.. ..

fairly cold, like 2 celcius, when powered up it shows voltage, kph, ah, watts, as expected.. but short ride later i look down and this :

The trike is still running fine, full power, so i pull over. disconnect and hook the power back up, the display comes back to normal and i ride again.. a few seconds later i'm back to black boxes.

the CA is calculating Ah , it shows an increase when i cycle the power, is this the cold temps ? or something else going on ?.

i've run the originals, V1, 2, etc. small screen way up into the minus double digits temps and never had this problem. bigger screen different ?

( June 1st update to this.. since weather has warmed up, this problem has not come back.. fyi )


May 8, 2012

Been taking the KMX out for rides almost every night, have had everyone i know try it ( at least 20 test pilots so far ) and gets big thumbs up from everyone..

Tonight the sky was grey but the urge to ride got me out again, this time my neighbor came along on his 100v 9C 100 amp bike

Went to the local park, was a school football game, plenty of questions and looks ( must remember to bring business cards when i go out on this thing, at least i had the shirt ! ) .. it's a chair anywhere you go.. pure awsome..

the PSI cells are good to go.. no sign of damage from the dead short incident, and delivering 7ah with voltage holding strong. cool.

the CA has been working properly since the weather has warmed up, no more black blocks.. yet...


May 9, 2012


I just ordered 6 of these to get started with, first time ordering nano's. :
Turnigy Nano-Tech 4.5ah


May 24, 2012

That was fast ! UPS arrived this morning..

All 6 cells , in all 6 packs are showing 3.810v to 3.820v on arrival, this is really good !!!...

Fully charging them all as i type this.. and monitor closely..

4 packs ballanced, charged, at 1C ( 4.5 amps ), and discharge at 100v from a portion of my lightbulbs at 5.25 amps, while the last 2 packs ballance charge.

I also received my Lyen 18 fet controller.. more on that shortly

An honest 4ah ! ( From 4.5ah cells ) from cycle 1.

I dont like to deep discharge packs, but it's the only way to know what's in there and prevent an overdischarge on the road when not using a BMS.. weakest cell dropped to 3.455v at the 4.0 mark all others at 3.5xx wich is just awsome

pack remained cool ( room temp is 23c , comfortable vacation weather !! ) .. up to the 3ah mark, and slowly got warm to 4ah when i pulled the plug.. outside pack temps 36 celcius


May 28, 2012

Out with the old.. In with the new !!

I love working with aluminum, light, easy to cut, drill and bend..

Cut a piece and bolted it to the controller..

I try to always add some tape between brackets and frames, keeps things quiet and protects paint..

Using the existing holes in the frame that were available for the cable mounts ( that broke during assembly ) ..

Going to be a short run between the motor and controller..

Changed the half-grip twist throttle for a thumb type, with 100v 60+ amps on tap i really dont want accidental power usage...

So i drilled a hole at the bottom of the steer tube and fed a guide wire ( weed wacker line ) to fish the throttle cable thru from the top of the tube, cleaner look

And then back to the kitchen workshop area, got the throttle cable extended (was 18" too short to reach the controller.. argh..

sorted out the motor/controller phase hall wire combo colors .. tested the 3 speed switch.. all working !!..

Today i assembled the 6 nano packs for 18S 2P fun, and i just ordered another 7 packs from the china warehouse (the US warehouse was out of stock.. ) it will be 24s 3p (100v 13.5 ah ) when all the packs get here.

Ok... Just got back from my first ride using the 18fet at 18 cell series ( 72v ) and aprox 60 battery amps showing on the Standalone CA !!!

Hell yeah this is FUN.... I predict tires and brake pad life are going to be short lived.. ( on grass or dry dirt it breaks traction and fishtails real nice.. )

Pictures to come, got the battery pack solidly mounted, no more vric vrac rattles !!!..

Also on the agenda, figure out how to enable and use Regen on these things.

backtracking a bit..

earlier today, cut some ABS plastic pieces...

Since i only have 6 packs at the moment, i'm running 2 in parallel ( 2P ) and then 3 of these in series for a total of 18S , 2P..

Using clamps, i applied pressure to the packs then with filament tape secured them tightly together in pairs.. then stacked them 3 tall staggered..

Looks sketchy, but for testing purposes , it works.. having learned the hard way i no longer waste time making everything perfect prior to road tests... nothing worse than spending hours shrink wrapping , zip ties, etc... only to find out you got a problem and have to tear it all up .

So last thing i did before parking it for the night ( after searching the forum for info on using regen.... ) is dig up a gutted e-brake lever switch, hooked it up to the e-brake ( black / yellow ) line, only problem is that this switch is button-pushed disabled vs the other type i need.. so i had to hold it down to use throttle..

one word to describe this... " AWSOME " !!!!....

Get rolling 50+ kph, hit the switch and the trike slows down generating 10 ~ 12 amps, nice smooth, no brake pad wear but yet strong solid braking action down to 10 kph or so.. love it..

Tomorrow, pre-charge resistor, contactor, and mounting of 3 speed switch.. also swap Stan Alone Cycle Analyst for a Direct Plugin unit..

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