Looks like this is my next project: Razor RSF650

I know this is the ebike section, but I'm posting my thread over here with the intent to get advice, experience, and opinions over here from the ebike crowd. I have a Trek w/ an Ebikeling 48V hub motor and a 72V Enduro EEB. I did do a search for "Razor RSF650" on endless sphere - there was only 1 result and didn't turn up anything. In addition, I am trying to stir up an interest for this platform with this thread for any and all who might be interested in doing the same thing.

My goal is to build a 72V Lithium Ion battery and stuff it in there and upgrade the motor and controller to go faster to hit 40mph.

Here it is:

It's only $500 bucks from amazon.
It has 36v Lead batteries w/ top speed of 17 mph.
There are upgrade kits available to bump it up to 48V.

So far I've what I've come up with is people are adding another 12v lead battery to bump it up to 48V, changing the sprockets, overvolting, and upgrading to a 48V motor. I have no idea how these kinds of motors perform, as I am only semi knowlegeable on rear hub motors for bikes.



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https://www.youtube.com/watch?v=yV1wGuEvHiQ

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https://support.electricscooterparts.com/support/discussions/topics/1000088322

https://support.electricscooterparts.com/support/discussions/topics/1000082854

Great little bike! Picked one up middle of last summer exactly because it looked like a promising project bike. Put several thousand miles on it so far. I gradually increased the power with shunt mods and added an ammeter to the lid compartment. Took the stock motor up to 4kw with a modded DROK brushed motor controller and 12s lipo. Motor got hot! :lol:

In its current stage I've completely replaced every part of the electrical system. 220amp Kelly controller 18s lipo and mophorm (kunray?) brushless motor. Running the controller maxed out. Pulls power wheelies and hits a gps speed of 42.4mph. It's a blast I ride it nearly every day. Rode the stock shock till both the bushings and the over travel bumper where toast. New shock is great! Much more road feedback and no more pogoing down the road at 40mph. :lol:

I actually joined this forum the other day with the intent of making a build thread for it. Maybe we can gather info here? I've torn this bike apart more times than I can count. Both stock and modified. Any questions feel free to ask.












Don't mind the duct tape fender extensions and mud flaps Had to do something urgently to protect the bike from the crazy amount of road salt and grit in my area. Working on 3d printing something to take its place.

I'd just like to add that I do not recommend upgrade kits or messing with additional 12v SLA batteries. I have a friend who went that route with severely lacking results. I view those kits as replacement parts not real upgrades. If you wanna go cheap mod the stock controller. The mosfets and internal relay are rated 80amp. I ran it at 50amp for about a month just fine before going brushless with a used, powerful and cheap kelly.

Let's see how much I can write before the string ensemble starts. Razor parts are way interchangable, my mx650 forks are bound to fit your bike and you'll have front shocks. What a kind and caring company to do that for us, right?

When I over volted my mx 12mph 650's they went maybe 3mph faster. Waste of time. But there are bigger motors that bolt in there. My phone won't run the websites so I don't have parts to link. Once you surpass 1200w you're moving into 50cc performance and better. If it's like them there's a problem of where to put more batteries.

If you want rear monoshock, there's a QS swingarm with 1000w and 2000w, if you figure fitment to the rear wheel space you then need to figure out about the shock mount. I'm working on that for a razor pocket mod, getting front shocks, (Just occurred to me I should see if the mx will fit) bigger wheels, QS swingarm if I can solve this.

You can hit a site such as powersportsmax.com looking for a hydraulic brake upgrade, I doubt the existing brakes are good enough once you have the big motor. These scooter sites tend to have them also.

Oops. I wrote this first, I sent as the lights went down, I'll write more later.

If you're gonna be running it through any kind of weather I'd suggest treating the motor with red insulating varnish as well.




Same applied to the stator side.

Good info on the disk brake upgrade Dauntless. Stock brakes are barely enough at 40mph even when tuned just so. Hydraulic will be required when I change gearing aiming for 55+mph. Also for those interested tires are rated for 43mph I believe. So be aware you'll be running them near their limit.

Stock #25 chain begins to suffer around 3kw. Began to lengthen considerably at 10kw and snapped at 15kw. Went with #25H heavy duty chain with slightly thicker links and presumably better steel. It's been holding up well for a few weeks now but at this power level custom sprockets for larger chains is probably warranted. Anyone have suggestions? Looks like electricscooterparts.com can do a custom setup for 420 chain. Might be a bit overkill a tight fit though.

Intermission.

Dang, totally missed there was already a rear shock. It looks like nice wheels and tires for 55, but isn't it just physically small? What is the new shock?

I've thought this could make an interesting bike, I'd just want someone's old one cheap, not a new one. But maybe I could put the 650 on a pocket mod.

Lights.

New shock is an X-PRO 270mm gas shock.

About the size, I'd consider it minimum viable size for an adult. I'm 6'2" 220lbs and can ride it rather comfortably with the bars just missing my knees in tight turns. Makes a hilariously nimble and quick ride with this kind of power. :lol: I'm a powersports enthusiast though so 40mph doesn't quite do it for me yet. :wink:

Agreed, I picked mine up second hand but mint condition for about half price. If I couldn't have found one that cheap I was just going to continue focusing solely on my Suzuki RMX250 conversion project.

Inductonaut:
Just what i was looking for!
Excellent pics!
I too am interested in what rear shock that is. I also noticed the motor has that one black plastic piece with the fan/cooling blades. Did that come with the motor or did you 3d print that?
Thank you for the advice not to go with those "upgrade" parts. I would be building the buildest18650 battery I could fit into the RSF650.


Dauntless: I thought I read that indeed the MX650 fork does fits the RSF650. I'll try to find the link to that webpage.

The fan is built into the motor to my complete surprise. Seems to work very well. Reading reviews of kunray motors I expected it to overheat and the magnets to possibly fly off. Neither of which seem to be an issue on this motor. Maybe it's a new revision? I picked up the mophorm branded motor on amazon under $90. Same with the X-Pro shock.

If you really do intend to go 40mph I'm not sure you'd want a springy front end from the MX. The stock rear shock was bad enough, a safety hazard I'd argue. When hitting decent bumps at that speed the handling was significantly upset until the undampened shock settled out. The X-Pro handles those situations quite nicely.

This thread discusses the MY1020 style Kunray motors with teardown pics of a slightly different motor without the fan. https://endless-sphere.com/forums/viewtopic.php?t=100331

Granted its now cooler autumn temperatures the highest case temp I've read with an IR thermometer is 105F after an hour run time.

I'm very curious if anyone with more technical motor knowledge than I knows the effects those steel bands around the magnets might have on performance? I'm guessing it could mess up the magnetic fields. I have the equipment and knowledge to vacuum bag a carbon/kevlar sleeve if replacing them would improve performance.

Very thankful for the tips. I saw a 72v motor pushing 3000w on ebay for $389.00 when I ran a search for "mophorn".

Trying to keep motor temps down? Is Statorade effective in these types of motors? Have you tried statorade?

Don't know about that motor although it looks identical to mine down to the mounts and label. For that money a QS 138 3000W would be a much better choice. Try checking amazon for Mophorn 1800W 48V which is the one I have. It's currently listed for $98. Don't be off put by its 1800W rating. I run mine at peak power levels almost 10x that for short bursts.

The same seller has a 60V version but it's specc'd at the same kv so I suspect its the same motor for more money. The 72v versions I've seen seem to be specc'd at a lower kv which for me was less desirable. I want it to spin fast!

About temps, mine are actually quite good from my experiences. 105F is barely warm to the touch. By contrast, I had taken the stock Unite 650W motor up above 190F at 48v the first day I got it! :lol: It was literally smoking. Took it apart and found a large glob of balancing epoxy had slightly discolored. Reassembled and ran for 2000 miles. Still works in fact it'd make a great motor for a relatively low powered project. They can handle a few kw with a low duty cycle.

Heat is actually a major limiting factor for the stock motors. We found that increasing the voltage from 36 to 48v had a massive impact on heating rate hitting 140-150F within 10-15 minutes. Increasing amps to from 30a to 45a actually helped alleviate this to a small extent because it would get up to speed quicker and amp draw would then decrease. This is why adding a 12v SLA had terrible results. My Unite generally ran cooler at 44v 90amps peak than it did at 48v 30amp.

Haven't tried statorade but I wouldn't think it'd be a good match for a motor with a 6000rpm fan blowing through it. Maybe others ca comment.

Inductonaut said:

Try checking amazon for Mophorn 1800W 48V which is the one I have. It's currently listed for $98. Don't be off put by its 1800W rating. I run mine at peak power levels almost 10x that for short bursts.

Click to expand...

Is this the same motor that is getting you to 42 mph? Will you be using this motor to go faster than 42 mph or will you be using a different motor?

All you need, though I question just a 32 amp controller.

https://www.amazon.com/Mophorn-Electric-Brushless-Controller-Motorcycle/dp/B07KF8M5W6

rockstar195 said:

Is this the same motor that is getting you to 42 mph? Will you be using this motor to go faster than 42 mph or will you be using a different motor?

Click to expand...

Yup mophorn 1800W. I'm definitely not pulling 1800W though, it would only run that power at 48v. Fully charged my pack is 75.6v so a cruising power of closer to 3KW. Yes I will be using this motor as I try to hit 50-60mph. I'm confident that it can do it because the power it still has at full speed is immense. I wired in an economy switch to limit the controller to 10kw most of the time to prevent flipping backwards accelerating out of corners. The bigger question for me is how hot it will get.

If you're going with this motor you'll need a much better controller than the ones supplied in the kits. If you're into wheelies and strong acceleration I found it got exciting around 100amps. Again I'm running 220 battery amps peak. The right battery and controller are everything to coaxing power through a motor. I've had good luck with my Kelly once I found the settings to adjust the throttle delay and throttle ramp speed.

Plenty of other great (probably better) options for a programmable controller that will really make your RSF fly. From my testing a 100amp 72v controller should handle 40mph quite well with some headroom. You'll need to be able to supply around 3kw continuous to maintain 40mph with this motor. Keep in mind voltage is important to achieve the greater than 6000rpm you'll need with stock gearing as well. Voltage sag needs to be taken into account.

Remember in going this route you will be running a cheap chinese motor well above its rated spec. Thats 100% my jam but it might not be for everyone. Just something to keep in mind.

ETA on you hitting the higher speeds?

And what is it like going 40mph on such a little bike?

In your opinion, is it doable to have this as a commuter with the "Inductonaut" setup?!

14 tooth motor sprocket is on order, hopefully sometime this week.

40mph is pretty stable. I thought it might get speed wobbles but that hasn't set in yet. Having a dampened shock helps it feel more controllable.

I guess it depends on your needs. If you're only going 5 miles each way it'd work fine but you are a rather small object, probably hard to see. For reference, the seat is lower than the rear tire on a full size bike...



I've been browsing all weather tires. I think they'd help maintain a bit more cornering confidence than the relatively slick razor tires. Something like this : https://www.revzilla.com/motorcycle/heidenau-k58-scooter-tires?gclid=EAIaIQobChMI0Pyh7M-F5gIV-R6tBh2nHwLNEAQYASABEgLId_D_BwE&gclsrc=aw.ds

Why the 14 and not an 11 tooth sprocket? Can you send a link to where to get it? Thought smaller was better.

Will you be using the stock rear wheel sprocket? How many teeth does it have?

In your opinion will the#25H be enough to handle the power and will it last?

Do you think the MX650 fork or any front fork with suspension is necessary or is the stock rigid one ok?

I'm ok with the rigid fork. Gives real precise steering. I've heard talk of adding pit bike forks but it wasn't worth the effort to me. If its not hydraulic or pneumatic dampened I don't recommend it for high speed use.

Electricscooterparts has wide selection of sprockets. Any of them labeled as MY1020 compatible should fit. https://www.electricscooterparts.com/sprockets25chain-motor.html

If I remember correctly the rear sprocket is 80 tooth. With an 11 tooth on the front that gives a ratio of 1:7.27

The 14 tooth with give a gearing ratio of 1:5.71 allowing the rear wheel to spin much faster.

From the research I've done most people are trying to gear down their MX650s and RSF650s because of the rather weak stock power. However as far as gearing goes on motorbikes in general, the stock ratio is quite low already.

With as much power as I'm running I hit top speed in just a few seconds, no need at all to gear down. Rough estimate the 14 tooth could go as fast as 53mph although likely less from increased air resistance. Smaller rear sprocket will probably also be required to hit 55mph.

One important mod I completely forgot to mention. The rear freewheel sprocket needs to be immobilized or perhaps completely removed if you'll be running a few kw or more. I've read reports of them giving out. The way I did it on two RSF650s was placing four spot welds 90 degrees apart around the freewheel. This has been working well for months and allows the possibility of regen braking.

An odd curiosity, the freewheel looks like it might be a standard push bike part with teeth around it that might match a bike chain. The actual rear sprocket uses those teeth to index the bolts. Imagine the top speed using that tiny thing! :lol:

The #25H chain has been working well for me so far. That said it is undersized and I do not trust it. When I ride I keep a short screwdriver on hand in case I need to remove the chain guard.

Quick mod to make chain noise MUCH quieter is to find a short section of tubing or hose that will fit snuggly over the bearings of the chain tensioner. It removes the steel on steel contact noise. I've been running it like that since august.

So the bike has 3 sprockets? One for the motor,
one for the rear wheel, and a rear freewheel sprocket?

Inductonaut said:

Quick mod to make chain noise MUCH quieter is to find a short section of tubing or hose that will fit snuggly over the bearings of the chain tensioner. It removes the steel on steel contact noise. I've been running it like that since august.

Click to expand...

Any pics of this mod?

The Heidenau K58 Scooter Tires you mentioned earlier are pricey but not that pricey...worth it if the stock tires are too slick.

Inductonaut, you tha man!
Dauntless thank you also!

The freewheel sprocket is sandwiched by the main rear wheel sprocket. The bolts that are holding it in place lace through the freewheel teeth. Seems to have been a clever way to reuse a bulk manufactured bike part.

I'll snap a picture of the chain tensioner mod next time I take it out riding. Probably tomorrow.

The Heidenau's are just one of the more highly reviewed tires I've looked at. They have a good snow reputation and a very high speed rating at 81mph. There are a lot of other cheaper options too from Michelin etc. I'd say its a good bet that just about any name brand would improve over the razor tires. Stock tire size is 100/80-10.

One thing I always thought would be cool would be to put a 12 inch hub motor in the back and run 12's front and rear. Seems to have just enough clearance. Might take some work to get brakes working for such a setup.

I've seen on the web the newest kind of Mophorn motor was released November 9, 2019 or something like that. It's saying that it's a "BY1020D" motor with the following specs:

Voltage: 60V DC
Output: 2000W
Rated Current: 42A
Rated Speed: 5600RPM

I've seen it different places but here's the amazon link:
https://www.amazon.com/Mophorn-Elec...=1&keywords=BY1020D+60v&qid=1574772972&sr=8-1

Kv of the 48v 1800w version: 4500rpm/48v=93.75kv

Kv of the 60v 2000w version 5600rpm/60v=93.33kv

If the rpm specs are true it's likely the same winding in the same casing. Maybe you could get one, crack it open and find out for us!

I might do that and take one for the team. Lol.

So your saying it might be the exact same motor but they are advertising under different (but really the same) specs?

I just contacted electricscooterparts.com about the 2 motors and they said: 1) The 60V 2000W has higher RPM and more power than the 48V, 2) they are not the same motor,
and 3) The 60V has higher top speed.

Im waiting for a reply to see if they have o rcan recommend something more powerful than that.