Need help with replacement motor for Yamaha 12v Raptor

Need new motors? Grind a gearbox? Adding teeth to a pinion?
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Need help with replacement motor for Yamaha 12v Raptor

Post by Stylez78 »

Hi all,

So very quickly I did a search read a post from 4 years ago but didn't really get all the info about what to do.

I had this Yamaha 12v Raptor for my son and it was running well just slow for him since Christmas. I did the 18v drill battery mod about a month ago and just yesterday 1 motor blew. 1 back wheel spins the other is just dead.

I took the housing a part, go to the 2 gear boxes, took the bad side out and removed the motor. The gear box itself is a Dumar and seem to spin fine now that the motor is out. The motor itself is labeled 12v 12000rpm.

So a few thoughts I was having, since this is all a part should I look into upgrading the motors to something that would work with the stock gearboxes but could handle more power at 18v or even 24v? Is that even possible without opening up the gear boxes and replacing the gears with better quality parts, modifications etc?

Where could I source similar motors to the stock ones at 12v with similar teeth that might be better or more suited to handle the more power from the 18v drill batteries?

I am all for more speed but both my kids where very happy with the basic 18v power upgrade to the speed so I don't need to go crazy with the speed, but if I have to replace this motor anyway since it is shot, I'd like to look into what options I have.

I've never done this before but I like to tinker. I am not a machinest, so having to do major modifications to get something to work probably isn't the best for me right now, but slight mod stuff I could handle. Any info, guidance or direction would be greatly appreciated!

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Re: Need help with replacement motor for Yamaha 12v Raptor

Post by Hammer-fm »

I'm not familiar with that specific gearbox style, but it looks like it's not predrilled for a larger (775-size) motor, which has a 29mm bolt circle.If you're limited to 550-sized motors then you'll want to look at why the motor failed. 18V lightly-loaded should generally be fine for a 1k/V motor like this, but heavy loads can really turn into a lot of heat production quickly. is the vehicle driven up fairly steep slopes, through high-friction terrain such as loose sand or deep grass? If it's mostly pavement running then your heat production shouldn't be too substantial.

Judging by just the pictures, the gearbox doesn't appear to have any accommodation for allowing air into the front of the motor. Was there a spacer installed that isn't shown (it doesn't look likely based on the markings on the gearbox, which clearly show indentations from the motor vents)? If not, then that's problem #1 to solve. These motors pull air in from the holes on the nose and air is pushed out by the fan around the circumference at the rear of the flux sleeve. When the nose is up against a flat surface, there's nowhere to draw air in and therefore the fan is useless.

On the Fisher Price (eg. 7R) gearboxes, the plastic has raised sections that allow air flow into the motor (around the PVC pipe, which is in this picture for unrelated reasons :grinning: ).


I'm not aware of any source for a spacer specifically made for this type of motor, but you could build one from a thick washer with a grinder. I'd aim for at least 0.125" spacing. I think with the airflow problem fixed, you could buy replacement 12k RPM motors and they should hold up alright at 18V so long as you're not stressing them with really high loads (we ran our 4-wheel Fisher Price ATV around here for a good amount of time with a 18V ESC setup with a time-limited 'boost to 24V' mode without issues).
F-150 - 24-36V with homebrew 100A variable-speed motor controller, 4x 775 motors (no, it's NOT all-wheel-drive--look HERE for more details!)
Pink Rocket Princess Mustang - 15mph, 36V, 4x 775 motors, homebrew PWM controller rev 2....
Hurricane - 24V w/50A step-down controller, 775 motors
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