Broke my crankshaft and trying to find the right replacement

Mini Bike & Go-Kart Parts

#1
I have a non-hemi predator 212 and the crankshaft broke to the point where i can’t put my torque converter on. I’m trying to find a replacement part for it but all I can find specifically for predators are hemi cranks. I don’t know if those are compatible or not. I also found a tillotson crankshaft on gopowersports but idk if that is compatible either. Can someone please help me find a way to replace it? Preferably that’s around 50 dollars or less
 

mustangfrank

Well-Known Member
#2
I have a non-hemi predator 212 and the crankshaft broke to the point where i can’t put my torque converter on. I’m trying to find a replacement part for it but all I can find specifically for predators are hemi cranks. I don’t know if those are compatible or not. I also found a tillotson crankshaft on gopowersports but idk if that is compatible either. Can someone please help me find a way to replace it? Preferably that’s around 50 dollars or less
Pictures might be helpful...are you sure the crank is the only thing broken? I'm thinking even if it is just a crank and a gasket kit it would be easier just to buy another new engine as cheap as they are.
 
#3
Pictures might be helpful...are you sure the crank is the only thing broken? I'm thinking even if it is just a crank and a gasket kit it would be easier just to buy another new engine as cheap as they are.
Yeah, the only think wrong with the crank is the threads have been stripped apart. I bought it from someone and they were running it when the shaft screw for the torque converter was launched off. The reason mostly why i want to buy a new crank is cause i wanna learn how to swap them out. Added a picture too
 

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desert rat

Well-Known Member
#6
Find someone that is good with tapping and have them work it over. It can probably be saved. Did it break the bolt off? Clean the hole out to get the junk out , then use a taper tap to clean up what threads are left . Then use a bottoming tap to get more threads at the bottom of the hole. Then use a new longer bolt.
 
#8
Find someone that is good with tapping and have them work it over. It can probably be saved. Did it break the bolt off? Clean the hole out to get the junk out , then use a taper tap to clean up what threads are left . Then use a bottoming tap to get more threads at the bottom of the hole. Then use a new longer bolt.
Where would i find someone to do that? Also is it expensive?
 

Harquebus

Active Member
#9
Got close up pics of the end of the crankshaft?

Are there really no threads left or did the screw shear off and leave the rest of the screw inside the shaft?
This is unheard of but not impossible.
 
#10
Got close up pics of the end of the crankshaft?

Are there really no threads left or did the screw shear off and leave the rest of the screw inside the shaft?
This is unheard of but not impossible.
It seems like the previous owner shaved down part of the crankshaft that either broke off and was rigid or something like that. He also tried to drill is it and possibly retap it himself but gave up. But the inside has no threading left, it’s completely smooth
 

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mustangfrank

Well-Known Member
#11
It seems like the previous owner shaved down part of the crankshaft that either broke off and was rigid or something like that. He also tried to drill is it and possibly retap it himself but gave up. But the inside has no threading left, it’s completely smooth
If I'm looking at that correctly it looks like the bolt broke off in there...crank is toast.
 
#12
If I'm looking at that correctly it looks like the bolt broke off in there...crank is toast.
I know for sure it didn’t break off, the past owner just drilled a hole in the middle for some reason. So the different shapes your seeing in it is the depth of both holes, one that’s the normal size of the crank hole and a smaller one. I know it’s hard to tell from the pictures but just trust me on that fact.
 

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mustangfrank

Well-Known Member
#13
I know for sure it didn’t break off, the past owner just drilled a hole in the middle for some reason. So the different shapes your seeing in it is the depth of both holes, one that’s the normal size of the crank hole and a smaller one. I know it’s hard to tell from the pictures but just trust me on that fact.
Well the pictures are misleading then, how deep is the hole? Factory hole should be an inch and a half or so.
 
#14
I know for sure it didn’t break off, the past owner just drilled a hole in the middle for some reason. So the different shapes your seeing in it is the depth of both holes, one that’s the normal size of the crank hole and a smaller one. I know it’s hard to tell from the pictures but just trust me on that fact.
”the past owner just drilled a hole in the middle for some reason”
That reason is most likely because the bolt either broke off, or became stripped in the hole, and had to be drilled out.
Just from my experience ymmv etc
 
#15
Well the pictures are misleading then, how deep is the hole? Factory hole should be an inch and a half or so.
Yeah sorry about that, the hole is probably about 3/4 of an inch deep. The owner before me probably drilled out the the screw which was stripped and stuck in there and grinded down part of the crankshaft that could’ve been snapped and rough.
 

mustangfrank

Well-Known Member
#16
Yeah sorry about that, the hole is probably about 3/4 of an inch deep. The owner before me probably drilled out the the screw which was stripped and stuck in there and grinded down part of the crankshaft that could’ve been snapped and rough.
The usable part of the crankshaft should be 2-1/4" from the end to shoulder. Either way if it is cutoff 3/4" it is now too short to support a TAV/clutch or if the bolt is broken off in the hole the crank is toast.
 

Harquebus

Active Member
#17
I don't know what's going on with your crank. The photos are either out of focus or rather ambiguous. If there's a screw in there it 'can be' driven out with a reverse drill bit or screw extractor bit. Or, just drilled out with a regular drill bit and the remains hit with a tap to re-establish the threads.

If that fails and it's hopeless, look on ebay for people that sell Predator parts and buy a new/take-off crank. Or a whole new engine...

...the hole is probably about 3/4 of an inch deep. ...
Measure it. Got a cheap digital caliper from HF? Stick the depth measurement tang into the hole and get the reading. Or a toothpick and mark it with your thumb and measure it with a ruler.
 
#19
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The usable part of the crankshaft should be 2-1/4" from the end to shoulder. Either way if it is cutoff 3/4" it is now too short to support a TAV/clutch or if the bolt is broken off in the hole the crank is toast.
The shaft size is relatively the same size as stock, only slightly smaller, and the only difference is the inside of the shaft is shorter than i need it to be. I will be able to tap the hole and rethread it. Any suggestions as the what the size should be? It can’t be the stock 5/16 because the diameter is slightly larger.
 

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