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New motor and controller but loss of power

Hi Everyone! I'm so glad I found this website! Wish I knew of it sooner. Bought a used razor buggy. After a few days of enjoying the stock car, we decided to upgrade it for my kids. Started by replacing the stock batteries with 3 new 12 volt 12 ah batteries. The goal was to over volt the stock 24 volt motor. After doing this we got great results. Seemed to increase about 25% if speed but very little on torque if any. Then decided to upgrade motor and controller. Bought an amp flow G43-500. Suppose to have 3300 rpm at 24 volts no load. So I was expecting great things at 36 volts. I also bought a yiyun LB57 36 volt 1000 watt controller. It was a pain to figure out the install. The lock, brake and charger plugs were pretty straight forward. I got stuck forever with the throttle. Speed control has a 3 wire throttle but the razor stock throttle is 6 wire. Took several hours but I got it to work! I put the three wire controller throttle to the top three razor throttle. Then for the remaining three razor throttle wires I put two of them to the "indicator" controller plug and then the brown wire I left unplugged. I did quite a bit of testing so hopefully I didn't short anything. When done, car powered on and went forward. Seemed to have decent power when lifting the back up. However when I sat in it (150 lbs) it barely went. I know limit is 120 lbs but this car in stock form with 36 volt gave me a fast ride even at 150 lbs. Do I have a problem with the motor? Or controller? The motor was quite larger than stock and I did use original chain connecting to jack shaft. It seemed tighter than usual. Could that be the problem? Again car barely went forward with me in it. I hooked up the 36 volts of battery to the ground force we have and it shot out fast as expected. I don't have battery testers but seemed a lot faster than the 24 volt battery pack hooked to the ground force. Lastly...I think I hooked up charger corrected. The charging port plug from controller seemed to have The wires mixed red and black so that when I plugged into the charging port from the razor the black was connecting to the red and the red to the black so I switched it to line it up with each other. Don't know if that was a no-no. I switched it from the controller part only. When I hooked it up to my 36 V charger it was red for a good while and then it turn green signifying that the charge was complete Also the motor was running and usually loud. We only tested it for about 3 to 4 minutes in the motor did not get hot Any help would be appreciated! Thanks.
Since you installed a larger and more powerful motor and controller the dune buggy should of course have more power.

Since the go kart barely moves when it has a rider in it the first thing I suspect is that one of the batteries in the battery pack has failed which is causing the pack to drop Voltage and power under load.

I would start the diagnostic process with load testing the battery pack, and then load testing the individual batteries in the pack. We have a guide on how to do this available on this page:

If the battery pack passes the load test then it could be the motor, controller, or throttle that is causing the problem. I would start with load testing the battery pack first though.

If the battery pack passes the load test then please let us know and we will take it from there.

Please let us know if you have any questions.

I'm very impressed with the very informative and detailed help. I am currently out of town so I will buy a tester and test per the instructions you gave. Would the tight chain be a factor at all?
I do not think that a tight chain would effect the power output as much as you described because both the motor and axle rotate on sealed bearings which do not impart very much resistance under heavy loads.

Please let us know how it goes after you have a chance to take a look at it.
That makes sense! I actually want to do a similar (but yet successful upgrade for my other razor buggy. This time I'd like to buy parts directly from you so I know it will fit right and work. The goal is to get about 18-20 mph. This will be for my nephew 16 years old 115 lbs. I've seen SOOO many videos on YouTube but everything looks very complicated an expensive. I actually have a great source for batteries. I have 3x's 12 volt 9ah new ready to go. I like the idea of over volting since it sounds more affordable. I think I figured that If you over volt a motor you have to make sure the controller has enough watts to accommodate the increase in watts of the over volted motor? Let me know what I need please from your store. I was very attracted to the high rpm of the ampflow but since my troubles I haven't seen stellar reviews.
An overvolted motor will consume and output more power than it is rated for, so an oversized controller needs to be used with it in order to obtain gains in the motor's power. For example a 24 Volt 500 Watt motor running on 36 Volts can consume 36 Volts and 1000 Watts if the load applied to it demands that much power. So a 36 Volt 1000 Watt controller can be used with it.

Overvolted motors run at higher RPMs than they are rated at so the gear ratio between the overvolted motor and wheel will need to be correct for the size of the motor so it is not lugged, otherwise it will not be able to produce the extra power that it has the potential to, and may also overheat and burn out. For example a 24 Volt 2500 RPM motor running on 36 Volts will now run at around 3750 RPM. So the gear ratio needs to allow it to run at 3750 RPM when under full load so it is not lugged.

What we like to recommend for a Razor Dune Buggy power and speed upgrade is using a 36 Volt 1000 Watt motor and controller along with a 36 Volt battery pack. This way the motor will not be overvolted and will perform as the specifications indicate, and will also not be prone to overheating the way an overvolted motor is. Another benefit is that the chain speed will be lower than with an overvolted motor which will make the Dune Buggy run quieter.

A 36 Volt 1000 Watt motor will achieve a top speed of of around 23 MPH on the Razor Dune Buggy if the jackshaft is removed so the chain goes directly from the motor to the axle. Here is the gear ratio calculation showing this:


Our 36 Volt 1000 Watt motors have an 11 tooth sprocket for 8mm chain factory installed on them which can be changed over to our 11 tooth sprocket for #25 chain so it is compatible with the Razor Dune Buggy's axle sprocket.

The RPM of our motors are rated under load, so our 36 Volt 1000 Watt motor will run at 3000 RPM when it has a 1000 Watt load on it.

A 36 Volt 1000 Watt motor and controller will draw around 30 Amps of power when it is under full load, so the minimum battery pack size that we recommend for it is 15Ah (three 12 Volt 15Ah batteries). Batteries with a lower Ah rating than 15Ah may not be able to output 30 Amps for the full amount of ride time that they provide, and they may also overheat which could lower their lifespan, cause them to swell, or reduce their output power.

Here are a couple of 36 Volt 1000 Watt kits that we currently have for the Razor Dune Buggy:

Forward only, KIT-36300:

Forward and Reverse, KIT-36301: 

More Razor Dune Buggy kits can be found on this page:

Our kits are pre-wired so all of the parts are plug-and-plat right out of the box.

We can modify these kits so they do not include batteries, or in any other way.

We can also make a kit with a 36 Volt controller and 24 Volt motor that will be overvolted, however we can not guaranty that the parts in a kit like this will be compatible with each other and would consider it to be an experimental kit with no warranty on the parts if they burn out.
Thanks for the kit links. I think I have a few of hose parts already. Can't I just uE the stock on off switch and charging port even if I go to 36 volts battery, motor and controller? I have a 36 volt charger already. Will the 36 volt motor 1000 watt option with 36 volt battery be same speed as over volting a 24 volt 500 watt motor with 36 volt battery? Any benefit? That take off torque and top speed is what I'm looking for since this is a teenager. Also removing the jackshaft will increase speed but can I still drive on grass and street with slight climb? Do I lose torque? And what chain size/length do I get for motor direct to axle? Thanks!
The Razor Dune Buggy's stock power switch and charger port can be used with a 36 Volt battery pack, motor, and controller. The light in the switch is 24 Volts though so it should not be connected when the switch is being used with a 36 Volt battery pack. To disable the light simply disconnect the black wire running from the charger port to the switch.

When running on 36 Volts the 36 Volt 1000 Watt motor and 24 Volt 500 Watt motor will both create the same amount of horsepower however their shaft speeds will be different. The 36 Volt motor will run at 3000 RPM under load and the 24 Volt motor will run at 3750 RPM under load.

Both of these motor will work on the Razor Dune Buggy with the jackshaft removed. The 36 Volt 1000 Watt motor would provide a top speed around 23 MPH, and the 24 Volt 500 Watt motor overvolted to 36 Volts around 28 MPH.

With the 36 Volt 1000 Watt motor the top speed will be a little slower however the torque and hill climbing ability will be a lot better.

If you remove the jackshaft and install a 36 Volt 1000 Watt motor the torque and hill climbing will be twice as good as with the original motor because you are upgrading from a 250 Watt motor to a 1000 Watt motor (4X), but only doubling (2X) the top speed. With the jackshaft removed and the overvolted 24 Volt 500 Watt motor installed the hill climbing and torque will only be around 50% increased but the top speed will be nearly tripled.

The axle sprocket works with #25 heavy-duty chain. I do not know the exact chain length needed for this modification and recommend to buy a little more than will be needed and break it down to the right size after the motor is installed.

Please let us know if you have any questions.

Update: So I realized I might have changed some wires around the wrong way. The black and red wires from the controller battery plug did not match up with the battery plug from the batteries. I mistakenly changed the order coming from the controller so it would match. A friend with basic wiring knowledge told me because I did that The wires that come from the controller to the charger port were opposite of that going into the battery. I contacted the seller of the controller that I bought and he said I should have change the order coming from the battery not from the controller. I also ordered the wrong type of multi meter so I will be going to Walmart or Harbor freight to buy the right one later today. Just a little frustrated with all these mistakes I'm making. I'm so amazed at the knowledge of all the people on here and wish to get this right for the sake of my son and nephew. My friend suggested that I charge my 36 V of battery for a whole day before doing anything else. I have a 36 volt 1.5 ah charger and my batteries are 3x 12 volts 12 ah each. He said it would take 24 hours to charge. It makes sense but my charger light goes from red to green after about 4-5 hours. Something wrong there?

The battery pack wiring harness connector to controller battery connector wires should be matched up so red goes to red, and black goes to black. The charger port connector to controller charger connector wires should also be matched up this way. Of course the battery pack wiring harness needs to be properly connected to the batteries so its red wire is positive and black wire is negative in order for all of this to work.

The 36 Volt 1.5 Amp battery charger is the right size for a 36 Volt 12 Ah battery pack. When the batteries are brand new they should be charged for 12-24 hours even though the charger light will turn green earlier than that. Once that batteries have had their initial deep charge and have been used, then they can usually be recharged in around 6-8 hours if they have been deeply discharged, or less time than that if they have been lightly discharged. Once the battery charger light turns green then they are ready to use again.

Please let us know if you have any questions.

I made the mistake of never giving it a full charge as you specified. Drove the car around several go around a then charged it again for about 5-6 hours between uses. Are the batteries okay if I do the full charge now? Or did I mess them up? Prior to this recent upgrade they worked great. I'm just thinking once they are charged fully that maybe that would explain the loss of torque in the car. Most recently I charged it with the incorrect wiring I described previously (I only time I charged it after the upgrade). When I get the multimeter tool it should help me see if I am getting the right volage out of the batteries
Not giving the battery pack an initial deep charge will not damage the batteries. Just give them a good deep charge now and they will be fine.

If the charger port was wired in reverse polarity then the charger would either stop charging if it has a reverse polarity protection, or blow a fuse or burn out a part inside of it if it does not have reverse polarity protection. So if the charger is still working then it must have reverse polarity protection and it did not charge the batteries when the charger port was miswired.

If the battery pack was wired in reverse polarity to the controller then that will usually burn out the controller immediately. It is rare for a reverse polarity miswiring to partially damage a controller and lower its output power. Usually controllers either work at 100% power output or do not work at all.

I would give the battery pack a 12 hour long recharge and see how the Dune Buggy runs then.
Thanks for the info. Update: for what it's worth, I adjusted the motor placement and got the chain abit looser. Car actually went a little faster with slightly better torque. Yet not quite at the speed of the original stock 24 volt 350 watt motor. I know I was suppose to do the deep charge but had to take it off a bit to test if looser chains would help any. I tested my other buggy (yes I have another that I bought for $20 on offerup) using my friends lipo 24 volt battery. When I tested this battery before vs my other buggy with the over volted stock motor with 36 volt batteries, it was just slightly slower than the 36 volt but faster than the stock motor with stock batteries. My next objective is to charge up batteries for the complete 12 hours then test it again using the multimeter I purchased today. Also I had a new throttle come into today and it seems to give the same results as the stock throttle (except that it gives accurate battery reading since it's 36 volts). Will give another update after the full charge. Thanks again for the expertise
Here is a video of the performance: I apologize in advance for the video quality and if I wasn't thorough. First time doing something like this. Let me know also if I should take another video focusing on something else. Thanks in advance.

I watched your video and the quality of it looks good to me. I see how the dune buggy with the 36 Volt battery pack and overvolted 24 Volt 500 Watt motor is running very slow compared to how it should be running. This slowness could be caused by many things which I will list below:

  • Faulty battery or batteries in the battery pack: A small percent of brand new batteries are faulty so just because the batteries are brand new they should not be ruled out as being the problem. Test the Voltage of the battery pack when it is being driven to see if it drops. The battery indicator on the throttle will work for this. The full light should remain on the entire time that the cart is being test driven and the low light should not come on. A multimeter set to DC Volts can also be used for this test with good results being 41-42 Volts when the throttle is not engaged, and 40 or more Volts when the cart is being test driven. If the batteries have a Voltage drop problem then let us know and we will provide further troubleshooting help for them.
  • Problem with controller or throttle: To test for a problem with the controller or throttle that is effecting the power of the motor, put the back end of the dune buggy up on a cement or wood block so the rear wheels can spin freely in the air. Now fully engage the throttle and see how fast the wheels spin. Now unplug the battery pack and motor from the controller and connect the battery pack directly to the motor and see if the wheels spin faster than they did when power was going through the controller. Taking a couple of videos of this test and then comparing the sound made during each test might help. If you determine that the wheels are spinning faster with the battery pack connected directly to the motor then the controller or throttle could be causing the problem. If this test points towards the controller or throttle being the problem then let us know and we will offer more troubleshooting tips for these parts.
  • Mislabeled motor: I notice that the motor you have is a rebranded MY1020 or ZY1020 motor with the factory specifications label removed and a new distributor's label applied. Maybe the distributor made a mistake and applied their 24 Volt label to a 48 Volt motor. If that were the case then that would explain the lack of speed and power that the motor has when running on 36 Volts. I would make certain to prove this beyond the shadow of a doubt before contacting the motor distributor and blaming them for this though. You could purchase a cheap non-contact RPM tester online for around $10 and test the motor with a 24 Volt battery pack to see what its RPM is. If it is around 3300 RPM at 24 Volts then it is labeled correctly, however if it runs at a significantly lower RPM then it is either mislabeled or faulty.

Please let us know if you have any questions, and how it goes.

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