KMX Cobra

[wojtek]

yes i went to the bmx bike shop where they had only 14t freewheel. luckily i took the hub motor wheel and realized that it doesn't fit.

apparently there are 2 sizes of freewheel smaller and larger. so anything from 16t should fit the hub... not sure you can get less than 16t in the larger diameter size..

the freewheel i got was cheap chinese, thicker than standart 9 / 10 speed but it seems my 2010 kmx cobra does use thicker chain... i needed to add a bit of chain and that is where i noticed that some of my chain didnt fit and some did [8 speed chain, sram PG850 was good]

[Sacman]

Fishtailing will require a bit more power, right now it just " grabs " and i've had one of the front wheels way up in the air near tipping point lol... ( and yes.. i was leaning far over.. )

To pull a proper donut required enough power to break the tire loose and spin fast in relation to vehicle speed.... i'll get there !.. have faith !

You probably could... maybe not on asphalt but you could on a gravelly road.

[JohnC]

Ypedal and Sandy sighted in his new machine tear-assing around neighborhood.

[Ypedal]

Nice !!...

I been at this a long long time.... but not quite " that " long !.hehe.

[Ypedal]

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

Perfect spot to bolt up a monster torque arm once the high power controller lands..

[Ypedal]

Also removed rear shifter from right side handle and removed cable..

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 !

[Ypedal]

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

I like tape..

[Ypedal]

Cut a piece of black ABS, heated and bent to match the frame angle, will double side tape it and zip tie 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 can be centered with the seat and secured up there somehow.. that's a tonight plan.

[Sacman]

Nice!
A rear fender would be nice too... to keep the rear wheel from slinging muck onto your beautiful battery packs and controller.

[wojtek]

Cut a piece of black ABS, heated and bent to match the frame angle, will double side tape it and zip tie 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 can be centered with the seat and secured up there somehow.. that's a tonight plan.

any reason why you have not decided to place the battery packs in front of the trike? with RC motor it does make sense to put some weight at the back to have more grip on the rear drive wheel but with heavy hub motor at the rear, placing battery in front would significantly imrove handling and balance.. that is what most of the KMX users are saying.

[Ypedal]

Yeah, this is sort of temporary until the lipo comes in, these PSI cells would not enjoy the 80 or so amps i intend to deliver to the motor... The existing controller and battery come off in a month or so. good enough for now.

[Ypedal]

small update.

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

kmx44-hanger.JPG (43.84 KiB) Viewed 298 times

As simple as this sob 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.. )

[wojtek]

and it is just for a temporary battery mount
are you going to go for DOC's TAs ?
also have you taken out thse 2 white plastic thingies on the disc brake side?

I see your seat is very steep - is it how you like it or just need it to have enough clearance for the battery pack and controller?

re time spent, i totally feel you !!!

alraedy spent tens of hours on my KMX and it is still far from being finished!

As simple as this sob 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 !

[Ypedal]

Yeah, but since my version of " temporary " can be months, it was worth doing right enough to last..

I 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 mudguards !!!!!! ...

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 ) .. but found that once you hit 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 !!.. whoot !.

[Tommy L]

Nice Build Ypedal!

I've got the Catrike 700 with Bionx v3.8 with a 26" Rear. V3.8 is tweaked out and I get about 40kph on flats 52kph down hill.

My Catrike becomes very twitchy at 50kph. There's not much rake angle on my Catrike. But I guess that you need a low rake to get around
corners with a tadpole...

I've got 36 spoke custom front hubs. This seems to help with centrifugal force with higher speed turns. Speaking of which....*******....
going to orange here..... lol

Get your body weight out on the edge of seat of direction of turn and lean out!

You learn this technique pretty quick when you go up onto 2 wheels in a high speed turn! Wear gloves! Immediate reaction is to put hand
down on moving pavement!

Also get the big, tall and colourful "CAN YOU SEE ME" Flag

People cant see upright bicycles let alone when you are that low to the ground.... trust me! Get one! Be safe and alive!
Yeah yeah.... they don't look very sporty, I'd even go as far as sticking a 6 foot pole off the back with the flashing AMBER light! lol
At the speed you'll be going......you will look like an emergency vehicle! Might as well get the Compressed bottle Air horn too!
https://encrypted-tbn2.google.com/image ... knDsq9Kp3w


Happy Recumbent trike riding to you Ypedal!

Tommy L sends....

[Ypedal]

Time for an update !

lmao.. tommy.. hilarious.. but so true ! .. this weekend messing around in the garage, i kept going for short rips up the road, thru the construction yard.. back home.. work for a bit.. go for a ride.. got more ballzy 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 ?

[Ypedal]

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 .. )

so 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..

Without registering wtf i was about to do, 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 second cound ***... 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 thru the wires thru the smoke and luckily hooked the right wire to seperate the connection..

the anderson housing melted off and coated the connector..

[Ypedal]

Grabbed the pedals and yanked the trike out of the garage and 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 clear of 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..

[Ypedal]

also, now.. this was noticed 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 :

kmx47-ca.JPG (43.65 KiB) Viewed 301 times

The trike is still running fine, full power, so i pull over. disconnect and hook back up, the display comes back 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 ?

[Doctorbass]

also, now.. this was noticed 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 :

kmx47-ca.JPG

The trike is still running fine, full power, so i pull over. disconnect and hook back up, the display comes back 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 and never had this problem. bigger screen different ?

The only two times i got a display like that i was never able to repair it.. it was the chip inside that blew so i needed to send both to Justin

Doc

[Ypedal]

Doh. !

[sn0wchyld]

ha... happens to the best of us mate. Particularly when your playing with connections while your less than 100%. Ive done it too, shorting out a 20s pack. Luckily the bullet vaporised, all that happened is I ended up feeling like I'd just been starting at the sun for a moment or two. That and someone just jabbed me with 100cc's of adrenaline . Lucky you got away with nothing more than some fried connections and blown caps.

once you're back up and running... how bout some vids?

[Doctorbass]

Maybe time for upgrading to the new V3 cycle analyst

I contacted Justin to get one for my new Zero motorcycle

Doc

[Ypedal]

heh heh.. yeah.. when you screw up with Lipo you dont even get the connectors to clip in.. they vaporize instantly... lower C rate cells are not as volatile ( and these PSI cells are still capable ... compared to lower end 2C stuff )

[Tommy L]

Time for an update !

lmao.. tommy.. hilarious.. but so true !

Welcome to the 3 wheels of joy! \\m//