Putting a Predator 212cc on a Yerf Dog 3203

Sans holo

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The original Tecumseh Pro Sport finally locked up on me but found out that Harbor Freight sells a 212cc “Predator” engine that is supposedly a good fit for the this particular go kart. It was a fairly easy swap out however, I’ve realized the crankshaft on this new engine is much shorter than the original engine. Was hoping though shorter it would still work but first run with my son the clutch came flying off once he really mashed on the gas. There just isn’t enough meat on the crankshaft to give the clutch enough to hang onto. I have found a Tecumseh crankshaft for sale at bmikarts. It looks very similar to the predator crankshaft but doubt it could work in the predator engine. Anyone have any ideas.?
 

Hellion

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Nope, not interchangeable.

Not understanding your problem though, as the Rotaderp 212 should bolt right in as a replacement engine--unless of course the original engine
was much larger or some other geometry is different.

The clutch should not come flying off--provided of course that you have it secured with a bolt and washer on the end.

Post some pics. We like pics.
 

madprofessor

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I want to see a video of that clutch in flight. And a pic of it mounted on the shaft. Let me guess, a little piece of keystock and a setscrew. No bolt.
 

Bansil

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My 1st reaction would an obvious turbo LS swap... 😛

But, sadly that may have wait a few years if he killed his 6.5hp kart with mad throttle.

So like has been said, how much thread engagement did you have into the crank?

This is not an issue with these setups...🤔


Oh!!!! Welcome :welcome2:
 

Sans holo

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If you look at the pic with the red arrow, that piece of the shaft that is peeking out from inside piece of clutch is all that I have to meet the outside part of clutch. With my old engine I had triple the length past that inside clutch part for outside part to grab onto. 2nd pic is the shaft with no clutch parts on except for bushing that keeps the driver and driven lined up for belt. Last two pics are both with clutch fully on. Not bolted on just slid on for pic. Thanks for any ideas on this.
 

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madprofessor

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What in the world is your clutch doing so far out on that shaft? Is it because of that fat spacer? I get it that you don't have a backplate for your clutch (driver) and driven pulleys, but that just means you can get the clutch even closer to the motor (further onto the shaft). Apparently you're just stuck on one or two ideas about your existing setup:
(1): That your jackshaft carrying the driven pulley can't be moved over, or the pulley slid over on the jackshaft.
(2): That your motor can't be moved over either.
Attaching pics of a CVT (your setup, but with a backplate) on a Predator 212, so you can see that your fat spacer shouldn't be necessary. Mine has a spacer between the motor and clutch too, but only fat enough for what you see in pics. Either slide that motor to the left, that driven pulley to the right, or that jackshaft to the right.
 

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Sans holo

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I think the best option is going to be to slide the engine over. Will have to drill some new holes into frame to receive engine in new position and trim that bushing/spacer down to keep it all lined up. That would definitely give me what I need though.
 

madprofessor

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Guess your jackshaft has some adjusting slots cut for mounting it, so it can slide for chain tensioning. The motor would have to slide with it too, to maintain the right spread between the pulleys for belt tension. Not just some drilled holes for mounting the motor.
That or the motor has some adjusting slots and you just forgot about belt tensioning.
See the great advantage of having a backplate? The jackshaft is built into it, and you only slide the motor for chain tensioning. You could make a backplate of sorts that could carry the driven pulley and sprocket and mount it to the motor (see pics above), but of course a cheap Chinese CVT with brand new everything like I use is only about $60.
Go Kart Torque Converter Clutch Kit for 10T #40#41#420 and 3/4" 12T #35 2HP-7HP | eBay
 
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