HELP! Minibike Predator 224 Revs high wanting to take off on start and dies when trottle...??

Mrshopter

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I've very recently bought the Predator 224cc wanting to put it on my Minibike. Also buying a VM22 Carb and header for the 224 installing both. And mounting the engine on to the minibike. I should mention that I checked the Carb just incase it was dirty for some reason also changing the jet with a bigger one. Full Governor removed Aswell. But when I started it up the bike literally took off reving high... since I was now wary of that happening I put the bike on a stand so it wouldn't take off. I started the bike up again same thing happened but obviously didn't take off because it was on a stand. I let it warm up a little then tried to lower the idle speed on the Carb but to no real success the wheel was still spinning like someone was throttling the bike. I also should mention that at this time I didn't have the trottle cable connected... I tried tuning the whole Carb over and over to no success. Then I connected the trottle cable to see if it atleast trottled but when I tried to trottle the engine would die. I looked for vacuum leaks (none), Changed main jet and tuned Carb (no success), checked gas and lines (nothing wrong) oil check (nothing wrong). Checked spark (is fine). Can somebody please help me..?
 

madprofessor

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tried to lower the idle speed
Okay, how did you do it? Not familiar with the new 224, but the reliable 212's have a black plastic idle screw mounted horizontally over the top of the low jet. The idle screw literally contacts the moving part of the carb throttle, stops it from going any lower by simply running into the tip of the screw. Screwing it in/out lowers/raises the idle speed. If your idle screw is backed out so far that the tip of it doesn't touch anything, something must be stopping the carb's butterfly from closing up. Is the choke on? That does more than just snap it shut, but I'm not well-versed enough to explain that. Just know that lots of folks have confused which way to slide the choke lever for start/run. Try it with the choke in the opposite position.
BTW: If you upgraded the main jet, you need to do the same with the low jet. It really matters if both the carb's intake has been enlarged and the muffler has been removed. Otherwise, a larger main jet won't help you any.
 

Denny

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Mad, he has a vm22 carb. Aftermarket (motorcycle type). I have no experience tuning those so I am of no help. Sorry. But others on here have, so be patient. Some one will be around to help you shortly.
 

Mrshopter

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Okay, how did you do it? Not familiar with the new 224, but the reliable 212's have a black plastic idle screw mounted horizontally over the top of the low jet. The idle screw literally contacts the moving part of the carb throttle, stops it from going any lower by simply running into the tip of the screw. Screwing it in/out lowers/raises the idle speed. If your idle screw is backed out so far that the tip of it doesn't touch anything, something must be stopping the carb's butterfly from closing up. Is the choke on? That does more than just snap it shut, but I'm not well-versed enough to explain that. Just know that lots of folks have confused which way to slide the choke lever for start/run. Try it with the choke in the opposite position.
BTW: If you upgraded the main jet, you need to do the same with the low jet. It really matters if both the carb's intake has been enlarged and the muffler has been removed. Otherwise, a larger main jet won't help you any.
Reminder I am using an aftermarket VM22 carburetor. The Carb has an idle set screw on the side which low/raise idle depending on which way you screw it out. I've tried lowering the idle with this screw and I didn't really make a difference in my main problem which would be the the bike throttling up without touching the trottle. The wheel spins at the same high rpm weather which way I set the screw.
 

panchothedog

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I have two of those carburetor s and the first one I put on I had the exact same problem. I had a air leak. Very hard to tell with everything bolted together. Take the carb and manifold off of the engine. Put carb and manifold together on the bench where you can make sure that the O ring gasket on the back side of the
carb stays perfectly centered on the manifold. Impossible to see the orientation between the two while bolted to the engine. Once together bolt manifold to engine with carb already attached and tightened down.
I
 

Mrshopter

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I have two of those carburetor s and the first one I put on I had the exact same problem. I had a air leak. Very hard to tell with everything bolted together. Take the carb and manifold off of the engine. Put carb and manifold together on the bench where you can make sure that the O ring gasket on the back side of the
carb stays perfectly centered on the manifold. Impossible to see the orientation between the two while bolted to the engine. Once together bolt manifold to engine with carb already attached and tightened down.
I
I was thinking It had to do with a leak in the manifold. When I get home I'll try my best to line them up if they aren't already. And respond back
 

panchothedog

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Just played with the idle screw after that. Yes lining up the manifold and carburetor lowered RPM by about 1500 to 2000. Engine was totally uncontrollable at first. After you bolt them together leave the bolts loose enough so you can move it around a little, then looking into the manifold from the engine side it is easy to see the back side of the carburetor and it's O
ring. Needs to be dead on or air will enter at the joint between the two.
 

Mrshopter

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Just played with the idle screw after that. Yes lining up the manifold and carburetor lowered RPM by about 1500 to 2000. Engine was totally uncontrollable at first. After you bolt them together leave the bolts loose enough so you can move it around a little, then looking into the manifold from the engine side it is easy to see the back side of the carburetor and it's O
ring. Needs to be dead on or air will enter at the joint between the two.
I properly lined the carb up literally perfect I would say.. it does trottle now and doesn't cut out. But the back wheel still spins at high rpm
 

panchothedog

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So how low can you get it to idle down, regardless of what the back wheel is doing. I am not asking for exact RPM ( hell I don't even own tachometer and I have 5 karts and a mini bike ) but just for guessing purposes a nice pleasant idle is 1400 to 1600 and wide open before you removed the governor was
3600 so you should be able to make an educated ballpark estimate. What do you have for a drive system? Centrifugal clutch or torque converter. If you get the engine running can you let it down and hold it from moving with the brake.
I am trying to figure out if maybe you have a clutch issue going on at the same time .
 

Mrshopter

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So how low can you get it to idle down, regardless of what the back wheel is doing. I am not asking for exact RPM ( hell I don't even own tachometer and I have 5 karts and a mini bike ) but just for guessing purposes a nice pleasant idle is 1400 to 1600 and wide open before you removed the governor was
3600 so you should be able to make an educated ballpark estimate. What do you have for a drive system? Centrifugal clutch or torque converter. If you get the engine running can you let it down and hold it from moving with the brake.
I am trying to figure out if maybe you have a clutch issue going on at the same time
When the choke is on the back wheel has to be atleast spinning over or atleast 2500. But when I lower the choke it slows down alittle. When I fully turn off the choke even when warming the engine for couple minutes the engine dies. I could hold the brake to stop it but still is dangerous because of how high it is spinning. I'm using a centrifugal clutch.
 

jmaack

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Air leak most likely. Between that and idle screw your settings are way off. Remove and reinstall and lower idle screw.
 

Mrshopter

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Air leak most likely. Between that and idle screw your settings are way off. Remove and reinstall and lower idle screw.
An air leak from where the idle screw is? If you could post a picture that would be very helpful. I don't think there is anymore leak from the manifold.
 
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Mrshopter

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Anybody got a spare VM22 to give away? Good. I'll try to find somebody you can give it to. Convinced now that I never want one. Ever.
There not very bad I just probably got the bad one and/or I'm not very knowledgeable about carbs
 

Mrshopter

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I just need to figure out why the idle is so high that it's making the wheel speed and pretty fast. That's it atleast I hope... the idle screw doesn't seem to change the idle so I think it's a leak but I'm not 100% sure and if it is I don't know where... so if anyone has any other suggestions or ideas please put them here. Thanks
 

karl

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The aftermarket manifolds don't line up to the port exact, and include junk gaskets.

I make a thicker gasket, bolt the manifold/ gasket to the head, then use a long 1/4in
burr to smooth the transition, then finish by hand with sandpaper.

Guarantees unobstructed flow, and a perfect seal.

Never really had problems with the carb sealing, but pancho's got the right idea to make sure it's
lined up as well as possible.
 

Mrshopter

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The aftermarket manifolds don't line up to the port exact, and include junk gaskets.

I make a thicker gasket, bolt the manifold/ gasket to the head, then use a long 1/4in
burr to smooth the transition, then finish by hand with sandpaper.

Guarantees unobstructed flow, and a perfect seal.

Never really had problems with the carb sealing, but pancho's got the right idea to make sure it's
lined up as well as possible.
There seemed to have been an leak where the manifold meets both the head and the other side the carb before, I actually got a better gasket for the head side and for the carb side I lined it up with the o ring perfect and additionally sealed it. Then attached it. That fixed the problem with me being able to trottle and it dieing. The only problem left is the back wheel spinning. I haven't smooth nothing out though.
 
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