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Old 04-23-2019, 02:07 PM
Laura Laura is offline
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Default 212 Engine Question

I have a go kart with a Predator 212 engine. I can get it started this spring as long as the choke is closed and I hold the throttle open at least halfway. It will not stay running if I open the choke. If I keep the throttle open I can open the choke about 15 % to 20 % of the way but if I let off of the throttle much. It dies. Not enough fuel upon closing the choke....so does anyone know a simple solution? The engine ran fine on a stand this winter.
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Old 04-23-2019, 02:10 PM
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I am going to guess the carb is gummed up... take the carb off and thoroughly clean it, the main and idle jet especially. I would also put some fresh fuel in there.

--Daniel
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Old 04-23-2019, 02:21 PM
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Thanks will try it!
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Old 04-24-2019, 01:05 PM
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I have completely taken the carburetor apart and cleaned it including the jets.

It still has to have the choke closed and the throttle open to start it.
If i try to open the choke it begins to die. I can only allow the choke to be about 15% open or it will die immediately. All this while, the throttle must be open or it will die.

Any other suggestions? This was a new carburetor in january and it started and ran fine.
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Old 04-24-2019, 01:29 PM
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Was the jet that is under the idle screw also cleaned and the idle was adjusted with the screw? If you take the idle screw all the way out the idle jet should just pop off easily.

With my 212s if I try to use the choke when the engine does not need it, the engine coughs and complains.

Wondering if maybe there is a vacuum leak somewhere, all the gaskets still good? I know there is an old trick to spray starting fluid around the carb seals while running, and if the engine RPMs rise indicates a leak. Someone please correct me on this if I am wrong.

--Daniel
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Old 04-24-2019, 01:35 PM
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What is the idle screw supposed to be set at? 1 turn out, 2 turns out ????

Also, when i tried to take out the main jet (the long tube going up the middle of the bowl) it did not want to loosen or come out. Anyone seen this problem? Again, it was a new carb in january and has not been fooled with.
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Old 04-24-2019, 01:42 PM
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Honestly never counted the turns... I usually lift the driven axle off the ground, turn the idle screw a few turns and start the engine. If it does I add a couple of turns until it doesn't and then turn down until the idle is about right. I never measure mine with a tachometer I just go off sound.

When you say the long tube I think you mean the emulsion tube, the main jet is the piece the screws out. Normally just a small bang on it gets it out, or you can carefully push it form the inside to get it out. Def needs to come out to be cleaned.

--Daniel
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Old 04-24-2019, 02:07 PM
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So Daniel; you have a red arrow on the above photo. What is that? I took it out and expected to find a hole in the brass tube that is inserted in the plastic piece you show with red arrow. There is not a pass through hole in that brass tube. I tried running a torch tip cleaner through it and it bottoms out.

??? (the main jet is the piece the screws out. Normally just a small bang on it gets it out, or you can carefully push it form the inside to get it out.)

Please explain this. I take it the main jet is not the emulsion tube from what you say here. The jet that screws out can not be banged out....right?

It appeared to me that the jet near the base of the carb that screws out and has a spring around it is the idle jet. Or am I thinking too much like an auto carb.

---------- Post added at 04:07 PM ---------- Previous post was at 04:05 PM ----------

When I asked about the number of turns, I was asking about the jet at the base of the carb. That jet I was thinking as the idle jet.

With the throttle closed, that jet at the base of the carb (with spring) will have to feed fuel into the stream of air. Or I am thinking of my training in Weber racing carbs.

Last edited by Laura; 04-24-2019 at 02:08 PM. Reason: mising a word
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Old 04-24-2019, 02:45 PM
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Let me try and answer this one by one.

Quote:
Originally Posted by Laura View Post
So Daniel; you have a red arrow on the above photo. What is that? I took it out and expected to find a hole in the brass tube that is inserted in the plastic piece you show with red arrow. There is not a pass through hole in that brass tube. I tried running a torch tip cleaner through it and it bottoms out.
Correct, not a pass through hole. What happens is when the screw comes all the way out (which is the idle screw, phillips head) you have to pop that plastic piece out that is below the bottom of the screw. I normally use a small flat head screw driver and pop it out. Pop it out and spray carb cleaner all though that jet and the pathways in the carb.

Quote:
Originally Posted by Laura View Post
??? (the main jet is the piece the screws out. Normally just a small bang on it gets it out, or you can carefully push it form the inside to get it out.)

Please explain this. I take it the main jet is not the emulsion tube from what you say here. The jet that screws out can not be banged out....right?
The main jet is the brass looking thing on the right side of the picture attached, the emulsion tube is the one on the left. What happens is the main jet you unscrew using a flat screwdriver (the fits correctly, cannot be too big) and then the emulsion tube is held in by the main jet. Once the main jet is removed that tube should just pop out with little effort. The emulsion tube is visible if you look though the main body if the carb (second picture) and you can tap it down to get it to release.

Quote:
Originally Posted by Laura View Post
It appeared to me that the jet near the base of the carb that screws out and has a spring around it is the idle jet. Or am I thinking too much like an auto carb.
I believe that is the float bowl pin you are thinking of? Only thing I know of that has a spring. The idle jet is not inside the bowl of the carb but under the idle screw adjustment.

Quote:
Originally Posted by Laura View Post
When I asked about the number of turns, I was asking about the jet at the base of the carb. That jet I was thinking as the idle jet.

With the throttle closed, that jet at the base of the carb (with spring) will have to feed fuel into the stream of air. Or I am thinking of my training in Weber racing carbs.
The jet at the base of the carb needs to be just tight not too tight. Number of turns do not matter here as it just needs to sit there and the size of the hole in the middle regulates the flow.

The "jet" with the sprint (float bowl) is for fuel supply I believe, the bowl goes up when the bowl gets full and the pin cuts off the fuel supply. If you bowl is full when you take it off this is probably not the issue.

Hope that answers it, I am by no means an expert in this field just have had to clean my share of carbs .

--Daniel
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Old 04-24-2019, 02:59 PM
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Could we see a pic of how you have the carb setup on the motor??...
Maybe the springs arent in their correct spots..
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Old 04-25-2019, 07:59 AM
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Daniel you have been a lot of help. Thanks.

I am just getting started in fooling with go karts. I like to drive them but I also have several neighbor kids and dads that love them too. Keeps kids off of their phones.

I do have a lot of experience with Weber racing carbs as I have a 550 Spyder with dual Webers. They are great carbs but one has to know how to work on them with regularity.

Normally the "idle mixture screw" is the one at the base, or near where air enters the engine. When the throttle is closed air seeps around the throttle and through by pass holes and into the engine. It is at the throttle where the greatest vacuum is created when closed so fuel is sucked into the idle air stream. So, I think the brass needle valve with a spring on it screws into the idle mixture seat creating the correct mixture for idle. Normally that screw is lightly screwed in until at dead stop and then turned out 1 1/2 to 2 1/2 turns on most carbs I have tuned.

Normally the main jet is at the end of the emulsion tube as you said. I have not been able to get that jet out with any type of flat screw driver. It wants to damage the brass. It must have been seized in there from the factory since it is new.

I still don't under stand the little brass tube that is blocked off in the plastic insert. I think that is what you referred to as the idle jet? It looks like fuel could go through the hole in the plastic but where it goes I don't know.

Thanks again for all your insight.
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Old 04-25-2019, 08:26 AM
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Here's a few descriptions of the carbs and what is what...
The black screw controls the idle speed... underneath is the idle jet(black plastic plug)...
The back of the carb (shown here) shows an adjustable variant(not all are adjustable as they are epa/CARB controlled and factory set).
The main jet isnt adjustable off hand. it needs to be drilled or replaced with smaller orifice to set it to right plug conditions...



In these pics, it shows the jet and the E-tube and position of such... if the jet is taken out then the E-tube should fall out or be taken out by pushing it out from the bore...


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Old 04-26-2019, 05:00 AM
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Wow Thanks for the great diagrams. It looks like this is a Honda diagram but the clone is almost identical.

They are calling the brass screw with a spring around it the "pilot screw". It looks like from the fuel-air-mixture flow chart that the pilot screw and the pilot jet control the idle mixture ratio. It says to refer to the manual for the "number of turns out" in adjusting idle mixture. But then it talks about a cap. I assume the cap is to keep the number of turns adjustment the same at all times once the engine runs well. But it seems to say that if one takes that cap off, the screw will break. Surely that does not happen that often or does your experience say different?

Once again, thanks for all the guidance.

---------- Post added at 06:51 AM ---------- Previous post was at 06:42 AM ----------

My carburetor is a knock off I am sure but it did not come with a cap on the idle mixture screw (pilot screw). I did take the idle mixture screw (pilot screw) out to clean it and nothing broke.

I am still not in complete understanding of the pilot jet (the plastic device that has a brass pin in it but no pass through in the hollow pin). It looks like on the flow chart that air passes through the hole in the plastic and it also shows fuel passing upwards through the brass pin to mix with the air. But my brass pin has no pass through the best I can tell. Seems strange they would insert a brass pin but not use it to control something. I wonder if there is a very small hole in the brass pin that a small cleaning wire will not go through.

---------- Post added at 07:00 AM ---------- Previous post was at 06:51 AM ----------

If you look at the diagram at the upper left, right under where it says HONDA, it shows that fuel must have to go vertically in the jet to mix with air flow that is going horizontally. Then the pilot screw (with the spring on it) must then control the amount of mixture that is allowed into the engine during idle.

I am going to get out a magnifying glass and try to see a tiny hole in that brass pin in the pilot jet.

It is all beginning to make sense now, thanks to all of your help, especially these diagrams.
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Old 04-26-2019, 10:14 AM
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Ya that pilot jet has a really tiny hole, in the #70-80 number size hole...TINY..
I ended up making a holder for the jet to blow the thing out with an airgun... the best I could do to hold it right without shooting it across the room or blowing air into my finger....

Like I said... most clone carbs are factory set for idle mix(EPA and CARB environmental requirements)... so we do best on the main jet drilling and plug readings.... some have also meddled in the pilot jet drilling, but that gets tedious, need the ultra fine bits and patience....
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Old 04-26-2019, 01:25 PM
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I ordered a new carb again because the main jet would not come out with a screw driver. The carb I had trouble with was new in January and the engine ran great. Had not started it since mid February.

I received the new carb today and put it on......same problem. It will start with choke closed and throttle open. Then this one will run and idle with choke in open position and throttle in closed position but it will not run well while pulling a load unless I close the choke almost 90% closed. It just seems to be starved for fuel under load, with throttle open halfway or more and choke open. I can reach back and close the choke down to 15% open 85% closed and it has the power to pull the kart.

(yes, I did get a light and a magnifying glass and there is a "very tiny" hole in the pilot (idle) jet brass pin.) It seems to run okay at idle but not under power unless the choke is almost fully closed. A new carb did not help much. Seems maybe the fuel I have is a problem and is quickly plugging up the main jet. I will take this one apart if the jet will back out with a screw driver.
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Old 04-26-2019, 02:03 PM
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If it runs better with the choke on (is what I am taking you mean by closed, as in the butterfly valve closed) then it is running lean, by chocking it you in effect provided a richer fuel mixture. As far as I am aware of at this point it could be a fuel delivery issue or maybe a vacuum leak. I am sure other people will jump in here that have seen this before but to me if it runs under load fine with the choke on (valve closed) then its running too lean.

--Daniel

---------- Post added at 03:03 PM ---------- Previous post was at 02:38 PM ----------

This is a long shot but figured I would put it out there... make sure that the choke on/off is in the correct position. With a predator if the choke lever is pulled toward the rear of the engine (away from the fuel tank) the choke is on or in the start position, if the lever is toward the gas tank side or front of the engine the choke is in the run position or the choke is off.

Again a long shot but seems like the choke is doing the opposite of what its supposed to be.

--Daniel
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Old 04-26-2019, 02:40 PM
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I just tried starting and running it with the fuel tank cap loose to confirm there was ventilation so the fuel could drain okay to the tank under load. It still did not have power unless the choke was closed most of the way.

So I then took the newest carb off and something struck me. The new carbs came with 3 gaskets. One of them seemed to fit the holes etc but there is a groove on the engine side and also on the carb that appear to be a passage for air. The gasket has two holes for the mounting studs and another one that does not match up perfectly with anything. The additional small hole in the gasket does partly allow the groove to show on the base of the carb.

I also put a paper filter with adapter on the carb. The gasket where the adapter to the carb meet "could" possibly cover one of the small holes that seem to need air flow into them. I will check and make sure these holes are not blocked by a gasket.
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Old 04-26-2019, 03:55 PM
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Here is the layout of the gaskets....
Also inspect the phenolic insulator plate for cracks... it gets damaged sometimes apon re-tightening..




The gasket that mates with the airbox housing has the side notches on it...
Shown in the top of the pic...




If one were really careful, and the carb was free of gasoline and o-rings on the bottom of the carb.... You could apply a small amount heat to the end of the pickup where the jet is. That should help to free it up to unscrew....
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Old 04-27-2019, 07:01 AM
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Thanks again. I was not sure how this "black" phenolic insulator mounted etc. Good info and another possibility of a vacuum leak.

I have used a small amount of gasket maker on the gasket between the carb and the phenolic insulator. Started the engine with choke closed and the throttle partly open. It starts well and then idles down when I turn choke off or open. I can run up the rpm's to about half speed and it seems to run better. However, if I run the engine a couple minutes and at faster rpm, it just dies. I really believe my float bowls on the two carbs are not filling fast enough to operate under higher loads and rpm. This will be my next point of check along with the phenolic insulator. My fuel hose may have a kink in it under the tank.
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Old 04-27-2019, 07:24 AM
mckutzy mckutzy is offline
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The hose always looks kinked... typically its fine....

Another way to check for air leaks, is to spray carb cleaner at he joints of the carb when its running...Rev change will tell for a leak...

Is this a new motor????
If so why not get it warranty returned??
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