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Last Christmas my mini-me got a Doodlebug mini-bike. He rode it quite a bit but 97 cc's and 2.5 hp can only be so much fun for so long.
So whats a guy to do? If you asked that question do not read any further, you don't belong here, Nancy.
"Santa" brought a 212 cc Predator engine from Harbor Freight. This engine has been stuffed between the frame rails of mini-bikes for a number of years now and the reviews are all positive. "Santa" being the frugal type waited for Harbor Freight to put out a coupon book with a ticket for a 212 Predator for a whopping $99 bucks, just in case any of you following along at home get the urge to build one of these monsters.
Here is the mandatory "before" shot with the anorexic 97 cc turd.
Just a shot of the empty engine bay that is moments away from being stuffed full of 212 cc's and 6 hp of fire breathing fury.
What you see here is an adapter purchased from http://www.hotrodminibike.com. These guys make all manner of hop up parts for you mini-bike to include full on "stage" kits. "Santa" being on a bit of a budget due the recession decided to just order the adapter plate. This item allows for easy installation with minimal effort on your part. I also got a new chain as the "mini-bike" forums said the stock one is too short.
Once the plate is in position you drill four 5/16th holes at the rear of the adjustment slots as seen here.
There are 8 bolts, 4 attach the plate to the frame and allow fore and aft adjustment of the plate. The other 4 attach the engine to the plate to and allow port and starboard adjustment of the engine.
Out with the old and in with the new. The difference in size is obvious even from a low earth orbit. The new engine is massive in comparison.
Everything was going smoothly until we ran into some clearance issues.
A little gentle persuasion with a BFH and some strategically placed cargo straps allowed me to drop the eingine right into place.
After a quick start and static ops check I realized I forgot the retaining bolt for the new performance clutch. (purchased form Amazon) it became apparent that I forgot the nut when the clutch quickly detached itself from the crank shaft. After 3 trips to the hardware store to get the right bolt, we were up and running. **If you decide to do a transplant like this the Predator requires a 5/16 X 24 bolt on the crank shaft. This is odd because the rest of the engine is metric. Had I been smart enough to Google the size requirement on the first trip I would have only made one. oh well...I had to make spacers to keep the end play of the clutch to a minimum as seen here.
And here is the new engine shoehorned into place.
One thing that becomes obvious is the engine offset. The new one sits quite a bit to the right once the chain is aligned. It doesn't seem to make much of a difference in balance wen you ride it but it does make putting your right foot on the foot peg a little harder.
The amount of power the Predator makes over the stock Baja engine is amazing. Part throttle has this thing cooking faster that the stock one at WOT. I've adjusted the throttle stop but left the governor in place. I will eliminate it later once the boy gets used to the power this one makes. I ave him a pre-flight briefing and ensured he understood that this thing makes more power than the old one and to go easy on the throttle at first. He hopped on, gave it a little gas and it scared the crap out of him. After a few runs up and down the street he was running it WOT and grinning ear to ear.
So whats a guy to do? If you asked that question do not read any further, you don't belong here, Nancy.
"Santa" brought a 212 cc Predator engine from Harbor Freight. This engine has been stuffed between the frame rails of mini-bikes for a number of years now and the reviews are all positive. "Santa" being the frugal type waited for Harbor Freight to put out a coupon book with a ticket for a 212 Predator for a whopping $99 bucks, just in case any of you following along at home get the urge to build one of these monsters.
Here is the mandatory "before" shot with the anorexic 97 cc turd.
Just a shot of the empty engine bay that is moments away from being stuffed full of 212 cc's and 6 hp of fire breathing fury.
What you see here is an adapter purchased from http://www.hotrodminibike.com. These guys make all manner of hop up parts for you mini-bike to include full on "stage" kits. "Santa" being on a bit of a budget due the recession decided to just order the adapter plate. This item allows for easy installation with minimal effort on your part. I also got a new chain as the "mini-bike" forums said the stock one is too short.
Once the plate is in position you drill four 5/16th holes at the rear of the adjustment slots as seen here.
There are 8 bolts, 4 attach the plate to the frame and allow fore and aft adjustment of the plate. The other 4 attach the engine to the plate to and allow port and starboard adjustment of the engine.
Out with the old and in with the new. The difference in size is obvious even from a low earth orbit. The new engine is massive in comparison.
Everything was going smoothly until we ran into some clearance issues.
A little gentle persuasion with a BFH and some strategically placed cargo straps allowed me to drop the eingine right into place.
After a quick start and static ops check I realized I forgot the retaining bolt for the new performance clutch. (purchased form Amazon) it became apparent that I forgot the nut when the clutch quickly detached itself from the crank shaft. After 3 trips to the hardware store to get the right bolt, we were up and running. **If you decide to do a transplant like this the Predator requires a 5/16 X 24 bolt on the crank shaft. This is odd because the rest of the engine is metric. Had I been smart enough to Google the size requirement on the first trip I would have only made one. oh well...I had to make spacers to keep the end play of the clutch to a minimum as seen here.
And here is the new engine shoehorned into place.
One thing that becomes obvious is the engine offset. The new one sits quite a bit to the right once the chain is aligned. It doesn't seem to make much of a difference in balance wen you ride it but it does make putting your right foot on the foot peg a little harder.
The amount of power the Predator makes over the stock Baja engine is amazing. Part throttle has this thing cooking faster that the stock one at WOT. I've adjusted the throttle stop but left the governor in place. I will eliminate it later once the boy gets used to the power this one makes. I ave him a pre-flight briefing and ensured he understood that this thing makes more power than the old one and to go easy on the throttle at first. He hopped on, gave it a little gas and it scared the crap out of him. After a few runs up and down the street he was running it WOT and grinning ear to ear.
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