Wondering if you could all lend a hand & help me out. It has been a long 15yrs or more since i have rode or even worked on a minibike or small engine besides rc cars and minor things on my full size cars. I am not to mechanically inclined but can do certain things. I have been trying to sell some car audio equipment on craigslist and got a offer for a trade wich consists of a doodle bug plus cash. Seeing the bike brought back memories and i found this forum and i am thinking of going foward with the trade. I really wanted the cash but i'd love a mini even though there is no place to really ride out by me. So it's a stock doodle baja with the stock engine. I am a pretty big guy and i'd like to go with the predator swap. I wanted to know how hard the install is for say a newb , do i only need a clutch , chain and the engine mount or is more needed ? do i need to drill ? I would like to keep the cost down as much as possible. If anybody has a step by step install video they can provide i would really appreciate it or as much info as possible. I tried contacting Chris who did the install kits here but he is no longer making them and i liked that he provided a video. I see hotrodminibike has a kit but doesnt provide a video, anyway sorry to bother you all , happy to join the forum and hope to be a part of the crew soon - thanks
Doodlebug Predator Engine Swap Help Please
- Thread starter Justpassedu
- Start date
- Tags doodlebug engine predator swap
It's pretty basic. You'll pull the clutch off the existing engine and disconnect the throttle. Then put the new engine onto the same mounts and put the clutch back on and reconnect the throttle. If your chain doesn't line up, you may need to make some new holes on the engine plate before bolting it down. There are loads of videos on Youtube doing exactly what you're asking about.
Once you have that bigger motor on, you may want to consider a torque converter instead of a clutch. They really help if you're riding it on hills or off road, especially if you're north of 200 lbs.
Good luck!
Once you have that bigger motor on, you may want to consider a torque converter instead of a clutch. They really help if you're riding it on hills or off road, especially if you're north of 200 lbs.
Good luck!
I'm not sure if I read your post correctly but if the doodlebug the original poster has has the stock 97cc engine the clutch crank shaft bore is much too small for a predator 212s 3/4" shaft and he will need a new clutch.
To the original poster:
The swap is very easy and I was able to accomplish it within 2 days using a rotary tool and a drill. However I had aligned the motor incorrectly and had to go back in and correct this with my rotary tool. After I went on a ride and blew the OEM bearings on the back wheel.
I recommend changing those bearings as they are not great and left me with a 30 minute walk back. I used these bearings http://www.amazon.com/gp/product/B002BBOD68/ref=oh_details_o00_s00_i00?ie=UTF8&psc=1
I would still recommend using the adapter plate that PMR makes which is about 40 dollars plus shipping as the adapter is much more fool proof and allows for adjustment to alignment.
I opted to use a centrifugal clutch because I have had good experience with them and they can cost much under 100$. I found my clutch at a farm and fleet (they guessed what I was doing haha) the clutch was a Comet brand 12 tooth that is rated up to 8 hp and cost 50$. I was able to get by using the original chain by using a punch and hammer to shorten its length.
Also the throttle lever on the predator 212 will need to be modified by removing the friction washer that sits under the lever and by putting an extension spring onto the lever to another part of the motor to give better tension to the doodlebug throttle twister.
all this will give you a doodlebug that goes 35 mph with the stock 70 tooth sprocket the speed can be adjusted with a gearing change.
I am 130 lbs. If you weigh more you may want to go with the PMR jackshaft for the predator 212 for more torque as you change your gearing from the 70 tooth sprocket. Of course the end all solution for torque would be a torque converter however since you asked for lower cost I did not consider it for this post.
I hope this helps and have fun and be safe.
To the original poster:
The swap is very easy and I was able to accomplish it within 2 days using a rotary tool and a drill. However I had aligned the motor incorrectly and had to go back in and correct this with my rotary tool. After I went on a ride and blew the OEM bearings on the back wheel.
I recommend changing those bearings as they are not great and left me with a 30 minute walk back. I used these bearings http://www.amazon.com/gp/product/B002BBOD68/ref=oh_details_o00_s00_i00?ie=UTF8&psc=1
I would still recommend using the adapter plate that PMR makes which is about 40 dollars plus shipping as the adapter is much more fool proof and allows for adjustment to alignment.
I opted to use a centrifugal clutch because I have had good experience with them and they can cost much under 100$. I found my clutch at a farm and fleet (they guessed what I was doing haha) the clutch was a Comet brand 12 tooth that is rated up to 8 hp and cost 50$. I was able to get by using the original chain by using a punch and hammer to shorten its length.
Also the throttle lever on the predator 212 will need to be modified by removing the friction washer that sits under the lever and by putting an extension spring onto the lever to another part of the motor to give better tension to the doodlebug throttle twister.
all this will give you a doodlebug that goes 35 mph with the stock 70 tooth sprocket the speed can be adjusted with a gearing change.
I am 130 lbs. If you weigh more you may want to go with the PMR jackshaft for the predator 212 for more torque as you change your gearing from the 70 tooth sprocket. Of course the end all solution for torque would be a torque converter however since you asked for lower cost I did not consider it for this post.
I hope this helps and have fun and be safe.
Last edited:
You're gonna have to drill some holes. Check to see if anybody here is close to you. Who knows, maybe they'll show up with tools, their knowledge of mini bikes, and a case of beer to help you do this little project? You will be fine with a clutch. I'm 200lbs. and my doodle pulls me around just fine. I will warn you, thee things are addictive. Be prepared to spend money on a hobby that makes most folks scratch their heads. Welcome aboard. It's a blast!
Heck I weigh 191 lbs and the Predator 212cc does not need a jack shaft at all. I use a 12T Maxtorque clutch with the stock 70 tooth rear sprocket and it still has plenty of get up and go even with out the PMR jack shaft. In fact it was a wheelie machine that could throw unskilled riders who failed to lean forward when acelerating. I fixed that with 12lbs of steel plating. 8lbs over the front wheel and 4 lbs down low on the frame just infront of the engine. Much easier to control now after the addition of the weight
Thank you for the information. I myself am not very experienced with building these for heavier riders and have no baseline for comparative data. In fact I am not very experienced with building these at all my doodlebug is my first build. However I have been bitten by the bug and love to share the information I know and have gathered from reading threads.
Indeed they are wheelie machines at first. My first test run I did a wheelie for 20 feet and then put the front wheel back down. It freaked me out I have never even done a wheelie on my bicycle. I tried to remedy this with a 60 tooth sprocket on a sprocket adapter but it can still wheelie.
I painted my DB OD green and am planning to find an old steel gascan I can mount above the front fork for weight and for extra fuel as well as a 50. cal ammo box for the back of the bike for tool storage.
Indeed they are wheelie machines at first. My first test run I did a wheelie for 20 feet and then put the front wheel back down. It freaked me out I have never even done a wheelie on my bicycle. I tried to remedy this with a 60 tooth sprocket on a sprocket adapter but it can still wheelie.
I painted my DB OD green and am planning to find an old steel gascan I can mount above the front fork for weight and for extra fuel as well as a 50. cal ammo box for the back of the bike for tool storage.
Last edited:
Thank you all for your help , the deal fell though on the doodle bug and i quickly saw a add on cl the other night and jumped on it. From what i believe i think i got a baja warrior or something of that sort. I have not had much time to look at it but i scored it for $100. It has two flats and some rust but the owner said his son drove it maybe 10 times and it was sitting a few years in the garage and outside for a little bit. It def needs some work wich ill have to figure out , it has a 5.5hp engine on it.