Denzel 72v 4-spd Gearbox Build 125cc Dual Sport

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Re: Denzel 72v 4-spd Gearbox Build 125cc Dual Sport

Post by skeetab5780 » Apr 27 2020 7:02am

I was having no luck with the front brake caliper on the Zongshen dual sport and the front tire was very warped...

So i ripped the front end off the bike, and shitty ungreased ball bearing went flying all over my yard! I knew i was in for the long haul at this point!
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Long story short I decided to swap front ends with the old Apollo 250cc dirt bike solving a few issues and causing a few more in the process! My kind of style!

The forks for the Apollo are inverted and so much beefier than the stock, i should have thrown them on the scale since i know they weight even more...again who cares with this drive. But the mounting hardware is way bigger, the only safe way to do this swap would be to grind off the Zongshen frames headtube and weld on the properly sized larger one for the Apollo hardware to adapt.

But instead i just take a hack saw to it and weld the steel headset cups from the Apollo to my frame all ugly. The Apollo steerer barely fit inside the frame but it worked. The top welded much easier than the bottom since there was much more metal to weld to since i cut 1/2" off the top.
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I did a zoom in on my ugly welding skills, you would think by now i would be getting a little better...and i think i am. But i have trouble starting the arc sometimes and i tend to use too many amps and weld too hot to make up for it, also i'm still trying to figure out which stick movement pattern makes better welds i like small circles i think?
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If any problems arise ill have my brother Ben (professional welder) come clean it up later

So now that this front end is on the bike, i noticed that the handlebars are much taller now, i need to cut down the huge risers on the stock Apollo
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Notice how loose the chain is on this picture
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After changing the front end i went for a trail ride to test things out mainly just watching the front headtube welds out of fear for my life/curiosity

And then out of nowhere the bike goes full throttle in second gear on a rocky dirt trail and the first thing that comes to mind is to lock up the front brakes(luckily i now have them since i just put them on) and while doing this i take my left hand off the bars to kill the key switch(my only chance at stopping the motor) I was on a slight left hand turn causing the bike to go down hard on the left side causing the battery to fall out of the bike and the stress of locking up the brakes caused the motor brackets to bend backwards causing the chain to slacken alot...the drive is now doomed as the bike lay on top of my leg.

it is at this very moment that i thought, hmm if i had a huge elongated shifter on the drive at this time, i would have just snapped the shifter rod right off the drive. When you lay the bike on the left side, the BLDC motor is what touches the ground!!

The cause of this crash? Something i would have never expected. I zip tied my throttle cable to my front brake line, and the movement steering left to right caused only the black(ground wire) to snap off the connector while i was applying throttle, causing a out of control full signal without being able to stop! This is a first for me was scary with this much torque, luckily i was on a dirt trail in 2nd with no cars or cliffs around!

here is the zoom in on the connector that failed because it was really old and zip tied it bad
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So i spend all day Sunday taking the entire bike apart again! and reinforcing the bottom brackets with some hefty square channel that should not move now! And the bike is back in action with the chain nice and tight!

I did not take many pictures of any of this activity because it was off and on rain all day Sunday and i had to keep dragging the welder and tools inside and out.

this is the 3 1/8" piece of angle iron i welded in between the mounts to the frame tube
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Re: Denzel 72v 4-spd Gearbox Build 125cc Dual Sport

Post by fechter » Apr 27 2020 9:26am

Looks like it might be a good idea to see if you can tie in the brake lever switches (or at least one of them) to stop the motor. Most motorcycles have a kill switch on the handlebars too.
"One test is worth a thousand opinions"

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Re: Denzel 72v 4-spd Gearbox Build 125cc Dual Sport

Post by skeetab5780 » Apr 28 2020 8:29am

fechter wrote:
Apr 27 2020 9:26am
Looks like it might be a good idea to see if you can tie in the brake lever switches (or at least one of them) to stop the motor. Most motorcycles have a kill switch on the handlebars too.
Ya that may be a good idea! The stock front brake lever had a reed switch on it, maybe it will fit on this one...could be an easy install

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Re: Denzel 72v 4-spd Gearbox Build 125cc Dual Sport

Post by thoroughbred » Apr 28 2020 6:58pm

Wow that could have turned ugly. Yet another situation where a real clutch lever could have helped. Or a kill switch etc etc

To clarify, if you are riding with the throttle applied and a branch snags your throttle wire, the controller will apply full amps? 0-5k throttle?

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Re: Denzel 72v 4-spd Gearbox Build 125cc Dual Sport

Post by skeetab5780 » Apr 29 2020 5:34am

thoroughbred wrote:
Apr 28 2020 6:58pm
Wow that could have turned ugly. Yet another situation where a real clutch lever could have helped. Or a kill switch etc etc

To clarify, if you are riding with the throttle applied and a branch snags your throttle wire, the controller will apply full amps? 0-5k throttle?
Only if the negative wire breaks, which is super rare

Bike has been sitting under a tarp for two days since i have fixed it, hoping the rain dries up soon

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Re: Denzel 72v 4-spd Gearbox Build 125cc Dual Sport

Post by skeetab5780 » Apr 30 2020 8:25am

So my dirt bike just sits in my back yard getting rained on all day and night...It just has to rain every single day or night this month go figure, the month i decide to take it out and get it going... So annoying i wake up and forgot to put the tarp over the bike again....soaking wet for the 5th or 9th time i forget now

Anyway done with my rant, few pics of the bike rusting away nicely
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So i put a really Steampunk hand shifter on the bike for now...

Used a heat gun to heat the area to bend the drill extension since i do not own a torch yet
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Simple spade bit extension from the 15 year old toolbox
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I kind of eye balled where i wanted to weld it onto the foot shifter, but didnt think about having to use the foot shifter after the fact...i can downshift but i have to sneak my toe in around the extension. Will be an easy fit if i heat it and bend it a little more in two spots
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Used a old T handle Chinese cheap screwdriver for the handle for now, i can feel it on my left leg if i ride with my legs tight to the seat, again i think the two bends i need to make will solve this
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here is the resting position of lever
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Here is up shift position when toggled forward
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Side shot where its tucked in
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Zoom up close of my madness
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First test drive results were awesome since i can shift up and down now!~ I'm sure there will be situations where i will not be able to take my hand off the bars to get this done...But this thing is not crazy powerful at the moment so i went with it. Its super nice to be able to get into 3rd and 4th on the road real quick, even while doubling a passenger on back i can shift both ways. If im in a pinch in the trails i can still downshift with my foot also
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also i keep getting a internal reset 3-2 error code on my controller. I have to think its from voltage sag especially since i'm using a small low C rated pack with no Voltage display. I've never really checked the sag during load since i don't really care lol

I do however have a new 20s6p high C rated pack coming real soon that will deliver 60a peaks since the cells are true 10a rated cells. I will see if this solves the error code. Obviously i do want to get a voltage display on the bike some day, but i also want to spray paint over my rusty welds some day too! Never know when

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Re: Denzel 72v 4-spd Gearbox Build 125cc Dual Sport

Post by tylerwatts » Apr 30 2020 12:01pm

Hi skeetlab
I was thinking about your shifting and was going to suggest use a throttle on the left grip to twist forward or backward for shifting. Jot sure how much force your shifter needs but seems it would work well. Stick a throttle cam wheel on the shifter and attach the cables there. Would need a fixed point for the sheaths of course but seemed nice to have the shifter on the bars.

I like your tractor shifter too by the way! If it ain't broke... (don't fix it)

Cheers
Tyler



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Re: Denzel 72v 4-spd Gearbox Build 125cc Dual Sport

Post by skeetab5780 » Apr 30 2020 4:04pm

It is really hard to shift at the moment, not sure if its because the drive is new or not? If i had to guess its 2x harder than shifting a honda motorcycle. To go further into detail, before i added the hand lever, it was impossible to shift the little chrome foot lever im using with your hand...it was too hard to do

Throttle definitely wont be enough, but i did think about a clutch lever and cable...that would give you enough force to shift, but then ill have the same issue of only being able to cycle the gears one direction.

I think i could potentially make a usable foot lever but if i ever did crash again on the left side the shift rod would almost certainly get damaged possibly beyond repair since its sticks out so far causing the weight of the entire bike to smash it into the ground

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Re: Denzel 72v 4-spd Gearbox Build 125cc Dual Sport

Post by tylerwatts » Apr 30 2020 5:06pm

I suspect the problem is the gearbox is designed for an ICE and you only change gear when the power is cut and the engine slowly reduces speed enough for it to match the speed of the next gear. The electric motor doesn't do this and the gearbox synchros (if it even has any) just can't match it.

One way to help would be if you could set the controller to trickle some power to the motor to prevent the revs dropping. Otherwise you need to ease off the throttle then change gear gently on the lever to let the gears match and change. Not ideal for fun riding but hopefully you don't have to change that often either. And it might improve as the bike gets run in.

Cheers
Tyler


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Re: Denzel 72v 4-spd Gearbox Build 125cc Dual Sport

Post by skeetab5780 » May 06 2020 8:21am

Ya i agree, shifting is much smoother when you leave it running a bit while shifting...

So i doubled my battery pack to 240 cells 20s12p for a 30ah pack. I got out on the bike going thru the typical few miles of trails hopped the few downed trees, crossed a few rivers while trying not to dab and get my feet soaked. I was planning to get out and give the bike hell since it was nice out and i had plenty of AH's

Unfortunately i still do not know the area well im riding and do not know of many good trails yet! So this extremely rough trail caused the motor to start getting hot. This was a new experience for me since this drive has been like a tank, but i noticed the top speed in each gear seem to drop off to almost half performance...I was a little lost since i never thought about this drive overheating with only 1900w continous 4k peaks

So i decide to start heading home which is over a mile of road slight uphill from the trails. The bike was going to slow in 3rd WOT i could barely shift to 4th but it got there and i kept it held full throttle all the way home going only about 20mph when it typically is close to 37mph top speed fresh off charge.


This is a very big disappointment since this tank is no longer bulletproof IMO. Doubling the battery capacity did double the weight of the battery but this should not decrease performance this much over 15lbs weight gain

I am already looking into a different experiment using the stock manual transmission and a clutch, the problem is this will make it even heavier! Not sure if using a gearbox/transmission is worth it AGAIN...the stock bottom end of the engine has got to weight 40lbs if i had to guess, and then i need a 20lb motor to run the drive and 30lbs of batteries

making the drivetrain close to 100lbs powered! this making the bike likely around 300lb plus 230lb rider weight = heavy ass ride!

I still want to try it out just to get a feel for how a E clutch will work in relation to a ICE

WHY oh WHY am i so good at overheating motors! The motor did not "smoke" it is fine, after i got back home it was pretty hot to the touch, similiar to the BHT on the Apollo dirt bike(i could touch it but only keep my had held for a few seconds)

Im sure now the drive will operate fine, but for how long? 5 miles of light use? at this rate I am not so happy with the massive weight the batteries need to lug around when it is not up to carrying the loads effectively/reliably

Im glad this happened though since i was just about to spend almost $100 on a 12v pull solenoid to shift this pig and now i wont be doing that

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Re: Denzel 72v 4-spd Gearbox Build 125cc Dual Sport

Post by Overclocker » May 06 2020 10:48pm

skeetab5780 wrote:
May 06 2020 8:21am

WHY oh WHY am i so good at overheating motors!


:lol:

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Re: Denzel 72v 4-spd Gearbox Build 125cc Dual Sport

Post by tylerwatts » May 08 2020 4:04pm

Hi skeetab
I suspect actually you are using too high a gear rather than using the motor revs a bit more. Like going to top gear when you can't hit half the top seed is just putting lots of current through the motor. Seems like maybe something has shorted also. See if there's any burnt smell in the motor. It'd be cheaper to rewind it, get more power and copper into the motor and better performance. Don't give up on it yet, seemed very positive so far.

Cheers
Tyler


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Re: Denzel 72v 4-spd Gearbox Build 125cc Dual Sport

Post by skeetab5780 » May 11 2020 8:59am

tylerwatts wrote:
May 08 2020 4:04pm
Hi skeetab
I suspect actually you are using too high a gear rather than using the motor revs a bit more. Like going to top gear when you can't hit half the top seed is just putting lots of current through the motor. Seems like maybe something has shorted also. See if there's any burnt smell in the motor. It'd be cheaper to rewind it, get more power and copper into the motor and better performance. Don't give up on it yet, seemed very positive so far.

Cheers
Tyler
that doesn't make sense Tyler. First gear goes 8mph so being in 2nd gear trail riding is not too high of a gear...This is the gear 90% of the ride was in. Once it was already too hot(overheated) i used 3rd and 4th to get home and had reduced performance/top speed
and the 20s pack was at 80v still so it wasnt a current delivery issue

the motor is not burnt the bike still works perfectly fine, its just very odd how reduced the performance was when it reached its thermal limit, almost like the magnets had no energy left in them

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Re: Denzel 72v 4-spd Gearbox Build 125cc Dual Sport

Post by macribs » May 12 2020 2:05pm

its just very odd how reduced the performance was when it reached its thermal limit, almost like the magnets had no energy left in them
That could very well be the case, maybe motor got too hot and the magnets got de-magnetized?

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Re: Denzel 72v 4-spd Gearbox Build 125cc Dual Sport

Post by skeetab5780 » May 13 2020 9:55am

So i took the bike out last night for a rip, took the battery back apart for only 15ah since it makes it easier to throw in and out around and i now know this drive has its limits. It is still a ton of fun to ride around and the kids love to ride double on the back, they are so scared of the thing but i am already used to the mildly short torque curve so its not really enough for me to have fun fun

but its certainly a fun trail bike and I'll have to keep it in the fleet for a while. Soon ill have a different bike for every day of the week!

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Re: Denzel 72v 4-spd Gearbox Build 125cc Dual Sport

Post by Electric Earth » May 13 2020 7:28pm

Newbie question here, but I'm trying to learn about a potential e-moto build and am very interested in a gearbox.

If it has mega torque and rock crawler speeds in 1st and 2nd gear, and not a very high top speed, is there any reason to not change sprocket size to make it more usable in a street application? Could you build a small 60-70mph street bike with this?

Would there be any reason to not mount the motor/gearbox with the front end tilted up, in order to get the motor out of the way of the shifter/your foot?

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Re: Denzel 72v 4-spd Gearbox Build 125cc Dual Sport

Post by skeetab5780 » May 15 2020 7:06am

I would have to say no on the increased speed of 60-70mph since the motor is only 1200w once you get over 40mph wind resistance is a big issue and it would need over 2500w to sustain those speeds on flat ground nevermind a hill. You would likely overheat, but you never know if your lightweight and run a temp sensor you could get a commuter to maybe 50mph but you would have hot start stop issues in the summer.

and about the drive being tilted up...i guess you could do that but then you are raising the output shaft and also this has engine oil in it so it can leak out of the top overflow tube, and you dont gain much in shifting ability by doing this, also this drive bolts to the frame on the bottom

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Re: Denzel 72v 4-spd Gearbox Build 125cc Dual Sport

Post by skeetab5780 » May 15 2020 7:20am

I have never actually looked into this on a Kelly controller, But does anyone know if it is possible to have the motor continuously run at a low RPM even when the throttle is not applied to simulate a engine idleing? This may help with the shifting a bit

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Re: Denzel 72v 4-spd Gearbox Build 125cc Dual Sport

Post by john61ct » May 15 2020 8:15am

That is done with the Grin controllers (maybe CAv3?)

to simulate frictionless freewheeling with non-freewheeling motors

https://www.google.com/search?q=virtual ... eling+gmac


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Re: Denzel 72v 4-spd Gearbox Build 125cc Dual Sport

Post by skeetab5780 » May 15 2020 10:57am

john61ct wrote:
May 15 2020 8:15am
That is done with the Grin controllers (maybe CAv3?)

to simulate frictionless freewheeling with non-freewheeling motors

https://www.google.com/search?q=virtual ... eling+gmac
Skimmed thru that link real quick but i'm using Kelly not Grin and not a geared hub motor, not sure how this helps?

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Re: Denzel 72v 4-spd Gearbox Build 125cc Dual Sport

Post by skeetab5780 » Aug 30 2020 8:19pm

Got a bunch of new updates on the Denzel 4-Spd electric dirt bike build. New 35ah 100a peak battery, new throttle, new controls, new headlight and finally a new foot shifter that is working well

Had an issue with the front brakes locking up smoking the rotor hot but fixed it with a bleeding, this was causing reduced range and acceleration big time until i figured it out


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Re: Denzel 72v 4-spd Gearbox Build 125cc Dual Sport

Post by skeetab5780 » Aug 31 2020 6:23am

Shot of the bike just before i tore off the tractor hand shifter!
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Cut apart three different shifters and welded this contraption, actually works pretty good
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Shot of it on the bike
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different angle
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This is a shot at the end of the day after riding 30ah out of the pack
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Me and my daughter at the park
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Then back at the house to charge, i did try it out after it was dark to see how the headlight did at night...its just ok IMO they are more for looks
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I thought the bike was faster than this but on flat ground it has GPS 34mph which feels like 38mph to me

the VOLOCI's do about 31mph and this bike will catch up and pass it fairly easy in 4th
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Re: Denzel 72v 4-spd Gearbox Build 125cc Dual Sport

Post by skeetab5780 » Sep 02 2020 6:15am

Getting alot more use now that i can reliably jump on it and not worry about a break down. Typically i would ride a voloci or my Vector light bike around town but lately i've been choosing this beast

It now has a decent enough powerband with the stronger battery so i have been starting to try small jumps and goosing the throttle over rocks and obstacles and it lifts the front end right up, but if you do get the back end off the ground, the rear shocks do not like the landings!! ouch
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