Please read don't know what else to do.

#1
So i bought a predator 212cc and had the intention of putting it on a go kart frame, i did it and it worked for a while. the engine when i took it off choke and feathered the throttle it would start to rev up buy itself and made an unusual high pitched noise. not like scraping like a two stroke at high rpms. i didnt know what to do so i took it back to the store and traded it for another one and it now does the same thing. auto teacher said its probably running lean. Im stuck havent done anything to it besides put oil and gas in it. thanks for any help.
 
#2
Two new engines having the same problem? Unlikely...

I suspect your problem is in the throttle linkage not allowing the throttle blade to close completely at idle position.

Check and let us know.

Good luck
mardyn
 
#3
I checked the functionality of the crab a few times. and plus if the throttle was open a little would that cause it to max out?
thanks
 
#4
I'm just guessing here but... something is probably holding the primary throttle blade slightly open, that's why when you take off the choke, the engine starts to rev up. Could be tied in with the governor linkage as well.

Not sure on the other noise... may be the clutch chattering or trying to engage.

mardyn
 

DaddyJohn

Active Member
#5
When you take the engine out of the box, new and unmodified, you'll see the throttle lever on the side.
Once you loosen the pivot screw/nut a little to allow for freer movement, you can move it, and it self-returns.

If you were to run the engine without a throttle cable hooked-up, you can rev it up with the lever, let the lever go, and it will settle back to idle.

When you hook your throttle cable up, it should self-return in the same way.
If not, something is amiss with the throttle cable or whatever its hooked to (if a pedal, maybe the return spring isn't working properly).
 
#6
If that is the issue...keep in mind there's also a wavy washer in that throttle lever pivot point assembly, which was used to make fixed speed applications work good. Replace that wavy washer with a slick flat washer, and it frees it up even more.

Eric shows it on one of his episodes of the Gray Goat Garage.
 
#7
I had to work on the throttle Assembly to hook it up to a throttle cable it doesn't get stuck. and i took the washer out for more freer movement. it definitely doesn't seem like it has anything to do with the throttle. because it does accelerate at an uncontrollable rate by itself and its not like right after i take the choke off its after i feather the throttle to try to warm up the engine
 
#13
Stand on the right side of the engine. Start it up. Watch the long arm of the governor. If it moves and takes off and the engine revs up much faster than the idle, the governor is causing the problem.
 

SAS289

Active Member
#16
Does this happen with your throttle cable completely removed from the engine?

Are you sure your throttle cable arrangement is not restricting the movement of the governor arm or it's linkage? When the throttle assembly on the engine is in the idle position with the engine off the carbs butterfly is open. When the engine starts with the throttle assembly in the idle position the governor is what moves the butterfly in the carb to the closed or idle position. If the governor arm and its linkage stay in the same position and cannot move after the engine is started it will rev with the choke open as it should because the butterfly in the carb is nearly wide open.

You should be able to freely move the linkage that goes to carb to the right (going away from the carb) with the engine off. If you cannot you will need to find out why it is stuck in that position.
 
#20
Remove the governor, swap in a billet rod, billet flywheel and get rid of the stock carb. Get a 22mm Chikuni setup and call it a day. This setup works fine with the stock muffler too. It's not optimal, but the noise from a header isn't worth any gains you might see.

Messing with the mess that's the stock throttle setup on these engines isn't worth it IMO. Too much loosen this and that and add a spring here. Yes, I'd rather pull an engine completely apart than try to make a stock throttle linkage work.
 
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