Rieju 50cc conversion

larsb

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Joined
Dec 10, 2014
Messages
2,820
Location
Gothenburg, Sweden
Well, i crashed my old Kona Stinky ride, resulting in broken fork and wheels (and pride)

I've spent 15000km and two painful winters of commuting on this bike, RIP..


It was time to start a new ride. I decided to go for a moped conversion to get more durability and real estate. I can tell you it’s frustrating dealing with 16 year old kids.. And trust me, it's not good to buy a two wheeler anything out of a barn in the swedish winter 8)

I ended up with a spanish made Rieju RR 50cc bike from 1998. It was in a really beat up condition but the main thing was to get a frame older than the change to EU regulations so that it's allowed to go on bike paths with a decent top speed.

Some pics:
Trying to find the location for stuff that i moved from the Kona:
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First revision finished:
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New stuff:
rear shock, rear brake assy, steer head bearing, battery pack

from another bike:
Front shock
seat
wheels
bars

Motor: rewound revolt rv120pro
Controller: kelly kls72300
Battery: 200 tired 18650 cells, 100 new in the pack under the seat.

I have 300km on it already. I am planning to get rid of the chain and turn it into a belt drive later on, apart from that i'll try to keep from doing anything on it :D
 
When i was young a friend had a Rieju 50cc and we often drove together.
Nice to see a conversion of this bike. This frame is anyway much better suited to the motor and the power it can do, so don't bother too much about the loss of the crashed kona bike.

At the moment i am also working on a middrive conversion which i think is very similar to yours in terms of power (link in signature) but i have problems with the contoller.
The Adaptto Max-E blew 6 FET's when i set above 300A phase. The problem is the low resistance and inducatance of the motor which could make it really hard for controllers.

I wonder if you have measured above mentioned motor charactersistics?
Does the kelly controller work well together with this motor?

btw: nice battery shape :)
 
It's 15mohm 0.132mH phase-phase averaged between the phases.

The kelly cannot take it really, it resets at full throttle in mid rpm. I am waiting for a powervelocity controller right now to have as a spare if/when the kelly breaks. 8)
 
I am a bit impressed with the cheap and functional designs on the Rieju. Some thought has gone into keeping the manufacturing and assembly simple. Still they sold for 3000€ in sweden - i guess that they made an ok profit on these mopeds :D
 
Kelly controller died yesterday. It was fine when i drove home, after charging no output..

I get a big spark when connecting charger to battery, i wonder if this current spike blew something in the controller.

I always thought that this current only would affect the charger since controller and battery is already at same voltage. But if charger is fed current from the controller in this first inrush then it's possible (i guess)

Can someone elaborate on this?
Should there be a precharge on the charger connection?
 
larsb said:
Can someone elaborate on this?
Should there be a precharge on the charger connection?

It would be really strange if the controller died because of the inrush current from the charger.
Do you know whats the problem with it or any other findings so far?

Doing precharge on the charger connection is normally not necessary.
Does it also spark if you turn on the charger before you connect it to the battery? Some of my chargers will do if i don't follow this sequence.
 
The charger is always on - it's inside my house so i just connect the cable to my ride on the outside. There's a nasty spark when i connect every time..

I have been thinking for some time to buy a satiator from ebike.ca to save the batteries, maybe this is my cue. Then i can slow charge when i have time or when it's cold, top up just a little etc.
 
I've received some parts for the belt drive conversion:
QS 138/70h 3000w mid drive motor together with the front and rear belt pulley from their mid drive kit and a Votol 150s controller.

105t 8M HTD rear pulley/30usd. Cheap for such a large chunk of alu:
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I think it will be easy to adapt to the rear wheel, i'll just cut off the hub and bearings, mill the stubs and make an adapter plate:
 
Belt pulley finished yesterday, turned out great :D

Milling done:
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Adapter plate fitted:
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Adapter plate is recessed 10mm for the belt to clear the tire, 20mm wide belt is tight to fit since the rear tire is 130mm wide.

I sort of wished i'd milled some spokes just for the decoration. Knew i would..shite
 
I am fabricating a new mount for the motor. It will clamp to the swing axle and use the existing holes on the motor sides:
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It will give me 10mm of sideways adjustment and the correct axle to axle distance for the belt.

I bet all but the sideplates could be 3Dprinted with enough strength, maybe i'll post the files here since this moped is pretty common in europe.

This is the idea:

I just realised that i need to remove the swing to fit the belt so the mount is not assembled with both sides and all screws yet.
 
The conversion of the large pulley looks well done. Good job!
Are you able to mount the belt guide flanges or at least one? It cannot harm..

larsb said:
I am fabricating a new mount for the motor. It will clamp to the swing axle and use the existing holes on the motor sides:
It will give me 10mm of sideways adjustment and the correct axle to axle distance for the belt.

Yeah the axle to axle distance is always "such a thing" on a belt drive. Have you found a standard belt length that fits?
Other critical things are alignment and parallelism of the pulleys, and of course the tension.

I wonder why you decided to clamp the motor holder to the swingarm? Because as this is a steel frame it should be easy to weld a holder to it to.
The clamping mechanism could be eventually to weak or at least it looks so from the photo. How do you prevent the motor so that it does not twist up and down under load?
 
I didn't want to weld something before i know how it will fit, i always doubt my measurements and thinking are 100% 8) the fit is so tight that i have only 2-3mm clearance either side of the belt.

Sideplates will be mounted, at least one side, they were riveted but i think it's doable to thread these holes in M5.

A belt with 220t / 1760 length is the closest fit, it will give a c-c distance of 61,6 cm so that's where the motor is :D

I will clamp the motor on the bottom by the shock mount of the motor to stop rotation and give extra stiffness.

I bought a Rosta belt tensioner to help with the tensioning. There is some added slack when the shock is compressed, i just hope to get it right with the tensioner :D
 
could you please tell what material and what thickness did you use for the mounts? is it aluminium alloy? thanks.

following your thread because i have rv-120 pro for my project and curious how long will it last..
 
Mounts are made of 5mm thick 6061 alu sheet and 15mmx100mm alu bar stock.

My rv120pro lasted about 17000 km and two winters on salted roads. I had to switch bearings 1 time due to corrosion and gravel in the bearing closest to the sprocket.

Rotor magnets corrosion eventually killed it -if you don't drive in salt then it would still have been OK.

I checked your build out, i must say you should switch motor. Only reason i used my revolt for such a long time is that it worked. It was never a good motor.
 
larsb said:
Mounts are made of 5mm thick 6061 alu sheet and 15mmx100mm alu bar stock.

My rv120pro lasted about 17000 km and two winters on salted roads. I had to switch bearings 1 time due to corrosion and gravel in the bearing closest to the sprocket.

Rotor magnets corrosion eventually killed it -if you don't drive in salt then it would still have been OK.

I checked your build out, i must say you should switch motor. Only reason i used my revolt for such a long time is that it worked. It was never a good motor.
thank you for your information. i can't wait to see your rides with that qsmotor. may be we better swap the motor too.
 
nicely done lars!
it is very important that the belt tensioner keeps the tension right, especially if you plan to use regen.

whats the max power the controller can provide?
 
Motor looks massive when mounted. Wouldn't surprise me if motor could handle peak current way past 385 Amp for few seconds. Should bring you north of 30 kw if you controller is capable. Anyway still at 27 kw that thing will be a freakin' rocket. About ten times the power bike had shipped from the factory. Man you will have a great time on the bike.
 
My battery is too tired to do 15kW, i believe i will get max10-12kW so there'll be a battery build coming when i have the time and energy. :D

But in just two months it 'll be time for studded tires so i guess it will be sometime next summer..
 
Milled the tensioner mount and an idler pulley for running the tensioner on the inside of the belt.
I decided tensioner won't work well on the outside of the belt since then tensioner force is up and tension will consequently be decreased when the swing moves upward.

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I cut the phase wires of the motor to fit the moped, turns out that it's enamelled winding wire of the tougher kind..

I tried removing enamel by grinding every wire, by soldering, then with emery cloth but the enamel didn't want to wear off evenly and it took too much time :D

In the end i chemically etched/removed enamel with a melted NaOH salt bath, worked well (although being slightly dangerous 8) )

One minute in the sizzling hot salt bath and the wires were totally clean from enamel.

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