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first build/new help needed. CRF450

Posted: Jan 09 2022 7:17pm
by glav
hi, as said its the first time i intend to do a build. i started reading and something seem still unclear to me about emoto bikes.

if this post is in the wrong section sorry

first the project i want.
ill get an CRF450 rolling shell with no engine on, no rad.

i plan on putting a qsmotor 138 70H to have the integratedf transmission 1:2.35 gear inside it. that way i dont get to add another chain from the other side etc.
-this be the kit ... mainSearch

i need to know. except the battery what part will i be missin to convert to electric.

what battery options do i get to put onto it, if not made myself. ( later )

do i absolutely need to change the rear wheel sprocket ? what speed am i looking at ( top )

i'dd appreciate help from anyone. links or anything


Re: first build/new help needed. CRF450

Posted: Jan 09 2022 8:27pm
by amberwolf
I strongly recommend reading all the other build threads in this section before you proceed. There is a lot of information in them regarding the questions you have (especially about batteries, speed, etc) and the process of decisions you'll need to make, that you can learn from.

Regarding top speed, that is something you choose, then you work backwards from there to find out what parts you need to achieve that speed. It's a complex function of the wheel size, gearing, motor kV (speed at voltage), battery voltage, available power (battery, controller) vs power needed for a certain speed vs the aerodynamics of the specific bike/rider, wind/weather, terrain (hills, slopes, road conditions, etc).

Various build threads have more info on that, where I or others have walked them thru or at least given basic advice on choices they needed to make before buying things.

You'll have to make those same choices, after you first decide exactly what you want the bike to do for you.

If you don't first define what you want it to do, and under what conditions it has to do that, then anything you buy for it could be a waste of money and have to be replaced with different stuff that *will* do what you want.

If you have already defined these things, you need to put them as a list in your post, along with the conditions it has to do them under, so that we have a reference to help you decide what is needed to do those things, under those conditions.

Re: first build/new help needed. CRF450

Posted: Jan 09 2022 8:52pm
by glav
thanks for the tips.

ya well battery and speed isnt the main concern here. i mean in time i can decide what i need but for now it ll be primary stuff.

as seen on this forum alot of people go with the qsmotor 138 70h V3. ill do the same, seems to fit alot of riding styles and prices.
i will also go with the EM150 controller. they also match together and like said this all new to me.
the alibaba kit seems pretty much complete ?

its more about what else i expectdo i need. kill switch etc.


Re: first build/new help needed. CRF450

Posted: Jan 14 2022 3:20pm
by KiefRichards
Id contact QS directly. I just bought a 138 V3 with EM150/2 from them and the total cost with shipping was about $200 less than alibaba. Just fyi

Re: first build/new help needed. CRF450

Posted: Jan 14 2022 5:00pm
by amberwolf
its more about what else i expectdo i need. kill switch etc.
If you just want a basic list of parts you should probably have on hand, this includes everything I could think of in a few minutes. (You may have some things already; I can't know and tried not to assume you do). To really get you the right list, we have to know what you need to do and what you have/etc. :

--crimpers for all the different connector pins you may have to install (no idea what those are without knowing what else you have to plug in and what connectors they have), --spare pins for them, and matching connector shells for anything that doesnt' have them
--wire of appropriate gauges and lengths to connect everything,
--heatshrink as needed for wiring or connectors, etc
--soldering station capable of whatever soldering, if any, that you have to do
--mechanical tools to do all the building / machining of mounting brackets, guides, covers, casings, etc., that you'll need to attach the kit to the bike, and later the battery, and make them look the way you want.
--mechanical tools to do the disassembly/assembly work (wrenches/screwdrivers/etc)
--contactor (to break all connection between battery and controller whenever you don't want it operating
--diode appropriate to the contactor if it doesnt' ahve this built in
--keyswitch (to operate contactor, and possibly also the controller's enable line, and possibly your accessories)
--emergency kill switch (I'd recommend a lanyard type you put on you so if you come off the bike for any reason it disables it)
--fuse and fuseholder appropriate to the voltage and current your system will use, worst-case, to mount at the battery terminal to protect system wiring / battery / etc from fire in case of shorts / faults.
--DC-DC for your lights and accessories appropriate to the battery voltage you'll run from and sufficient capability to reliably operate all lights and accessories you want
--ebrake switches for your brake levers to activate any electric braking or shutoff motor during braking operations, or appropriate connections or electronics to use the brake light switches from your existing levers to do this
--personally I'd use a cable operated throttle run off your original grip rather than replacing the bikes' controls with whatever that kit comes with
--programming cable, computer, and software for the controller to tune it to your needs, or device that can run whatever phone/tablet software it has if it is capable of that
--sprocket for motor or wheel or both that provides the gearing ratio you need for the results you want, if the stuff you have doesn't already do that
--chain to connect them
--chain tools to lengthen or shorten the chain if it's not the right number of links already
--chain tensioner(s) if required
--mounting brackets to put the motor on the bike, or materials to make them from
--mounting brackets to put the display on the bike, or materials to make them from
--mounting brackets to put the controller on the bike, or materials to make them from
--heatsink for the controller if it needs one for your usage, or materials to make one from
--mounting brackets to put the battery on the bike, or materials to make them from
--protective casing to enclose the battery in, or materials to make it from
--covers for wiring, connectors, etc., where needed, or materials to make them from
--basic multimeter for general troubleshooting, voltage testing, continuity testing, etc.
--wattmeter capable of measuring the worst-case current, voltage, watts that your system will ever see, for troubleshooting and verification

There's probably other stuff I didn't remember to put in the list, but that's as complete as I can make it in a short time.

To know what else you need, you first have to decide what you want the bike to do for you, and how you want it to do that. Some of the things make a great deal of difference to how you would set it up, and what you'd need to do those things.

If you don't want to do that, then you can look at other bikes that are working and just go with what they did.

More stuff below, regarding that:
glav wrote:
Jan 09 2022 8:52pm
ya well battery and speed isnt the main concern here. i mean in time i can decide what i need but for now it ll be primary stuff.
The reason for deciding what you want the bike to do for you *first* is because if you build it first, then decide you want it to do things it doesn't do, you then have to replace the stuff you already bought with new stuff that *will* do those things. Gets expensive very quickly.

the alibaba kit seems pretty much complete ?
I don't see an alibaba link. Are you referring to a different kit than your first post?
The aliexpress link there (English version below, original link was French) is very basic and is missing a lot of stuff most people would need. Which other parts you need will depend on your specific needs (what you want the bike to do, your DIY skills, etc).

This kit:
QS Motor 138 3000W V3 70H 5500W Max Continuous 72V 100KPH Mid Drive Motor With EM150-2SP Controller Conversion Kit For E-Bike ... mainSearch
Only has:
--throttle with some handlebar controls. At a guess those are probably lower quality than the ones already on your bike. You'll have to decide which ones are better, and which ones you want to use, and whether you want to deal with rewiring any controls that don't match the wiring already on your bike for those functions (and figuring out the wiring of them if you don't have a manual that tells you what hte bike's wiring is, and a wiring diagram that comes iwth the new ones to show you which wires are which).
--speedo/"dashboard" display
--optional wiring harness (presumably premade to connect exactly the things included in the kit, and your battery).

Whether it has all the parts needed to mount it to your bike and connect it to your drivetrain, I don't know, because that depends on what you want it to do, what you already have, and your DIY skills to make such things. (most people doing this stuff don't have much in the way of tools and skills to do all the fab work; I can't tell from your posts so far what you have or will need).

Can't tell you what speed you'd get out of it (which you asked in your first post) without knowing how you're connecting it to your bike, what size sprocket you have, what battery voltage you'll use, what the battery can support for current draw, what riding conditions it'll be used in (hills, flat, winds, your weight plus expected bike weight (which you need to know battery size for, which you need to know range, speed, power, budget etc expectations to determine), etc.).

If you want to see how this works, you can go to the and set up a basic bike (doesnt' have ot be anything like what you want), and use the "use as middrive" option in the custom-motor option window, so you can change gearing to see what happens to speed, power, torque, etc., and vary the slope, voltage,

Re: first build/new help needed. CRF450

Posted: Jan 14 2022 7:18pm
by glav
thanks for your reply as of for what i have right now. i am still in the process of fixing all the bearing of the rolling shell i bought.

the shell itself doesnt have any handles right now except a broken one.

i do have access to all tool and press, connector, tool and all that stuff, i am a car mechanic for the last 10 years

for what i want it to do i know that ill have most of what i want with the kit ordered. i dont expect to push this thing all the way to the maximum. most of my passion is in makin it work in the end, i will learn and work what i have to.

update on the build.
swingarm needle bearing seal lip is broken, seen when i took it appart. found a guy who has a machine shop. got new needle bearing kit in today. sending that on monday to have the swingarm kit fixed.

the linkage is shot too. all the bearings inside are are DONE. kit be coming soon.

i also plan on having new wheel bearing and shop around a little on marketplace to find myself a good front brake since i dont have any :(

I seen many build where people used the same " kit "and it seems to me its okay i wont be disappointed. If somehow i am i will modify it with time.

Re: first build/new help needed. CRF450

Posted: Jan 15 2022 10:55am
by SlowCo
Nice project!
Good luck and enjoy the proces. I'll be following the build. So please update with many photo's regularly :wink: