Predator 301 High Idle

[tsimnami]

Hey everyone,
Right now I’m running a modified predator 301 on my yerf dog 3020, and I decided to install a 40 series converter to keep up with some of the extra horses I’m making. However, the idle is running pretty high and the kart wants to take off on its own at idle. I’m measured it on my tach to be about 2260 RPM, which makes sense as the converter engages at 1600.

I never had this problem with my TAV2 30 series, which I think was because the belt on that was a bit looser.

I’ve tried adjusting the idle screw a few times, but if I go too low, the engine starts running a bit weird.

Does anyone have any idea how else I can approach this? Feel free to ask for more info and I can give it.

 

[Denny]

Are you sure you are adjusting the correct screw on the lever for the butterfly and not the mixture screw. You are right that idle is way too high. Did you replace or remove the carburetor? Is it back together or back on properly?

 

[tsimnami]

I've never adjusted or tampered with the carburetor before I encountered this issue. There is a chance that something could have been replaced incorrectly by the previous owner, though.

The screw that I was adjusting was the one circled in the attached picture. From my research, I was confident this was the idle control screw.



Thanks for the quick reply.

 

[OPmini]

I've never adjusted or tampered with the carburetor before I encountered this issue. There is a chance that something could have been replaced incorrectly by the previous owner, though.

The screw that I was adjusting was the one circled in the attached picture. From my research, I was confident this was the idle control screw.

View attachment 126421

Thanks for the quick reply.

yep thats the idle screw. Are you sure you put it back together right? It could be that your throttle is sticky or not adjusted right.

 

[tsimnami]

There's only one other point of concern that I can think of, and its that one of the pieces on the carburetor never fully returns. I always assumed this was designed as I never experienced an issue with it in the past. I attached some photos to this reply showing you what I mean, and I may try to start it tomorrow while holding that piece back myself to see if it lowers the idle revs.



The more I think about it, the more it makes sense that this is the problem.

 

[OPmini]

There's only one other point of concern that I can think of, and its that one of the pieces on the carburetor never fully returns. I always assumed this was designed as I never experienced an issue with it in the past. I attached some photos to this reply showing you what I mean, and I may try to start it tomorrow while holding that piece back myself to see if it lowers the idle revs.

View attachment 126433View attachment 126432

The more I think about it, the more it makes sense that this is the problem.

Run the engine and it should push it self back a certain amount, as the governor moderates the throttle. At least thats my experiance on 212s

 

[tsimnami]

Run the engine and it should push it self back a certain amount, as the governor moderates the throttle. At least thats my experiance on 212s

Sorry for the late reply! It’s been a busy week.

I got around to running it today and sure enough that piece got moved back. Problem must lie somewhere else, then.

 

[tsimnami]

Even more concerning is that when I started it up just after I sent this message, it began “idling” at 5000 rpm

 

[OPmini]

Even more concerning is that when I started it up just after I sent this message, it began “idling” at 5000 rpm

try disconnecting the throttle from the governer linkage and starting it that way

 

[tsimnami]

try disconnecting the throttle from the governer linkage and starting it that way

Disconnected, but unfortunately it’s still running in the 5000s. I suppose that rules out any problems with the throttle cable.

perhaps it’s possible there’s some kind of large-scale air leak on the valve cover or something?

 

[OPmini]

Disconnected, but unfortunately it’s still running in the 5000s. I suppose that rules out any problems with the throttle cable.

perhaps it’s possible there’s some kind of large-scale air leak on the valve cover or something?

Just spitballing, but try:
1. Adjusting the air-fuel mix
2. New carb
3. adjust valves
4. check timeing
5. replace the coil
6. check flywheel key
7. gap the coil
8. Check gaskets
9. check valves
10. check compression (engines with blown rings will run but only at higher rpms, my experiance)
11. replace throttle / governer linkage

 

[Denny]

I still have a concern that there is a missing spring not pulling the blades closed.

 

[tsimnami]

I still have a concern that there is a missing spring not pulling the blades closed.

I'll try to find some old pictures and see if there's any differences in the throttle setup. It's highly possible something removed itself or came off while the engines been off the kart for all this time.

If anyone else has a 301 with a working throttle/carb setup, would you mind sending in a picture?

 

[tsimnami]

Hi again everyone,
I’ve been trying out a few things over the last few weeks.
- Bought a new carb, but still running at high RPMs like the old one was.
- Tried on the old torque converter and that was fully engaging too.
- When I’m cranking the engine with the wheels off the ground, the wheels make a good full rotation before the engine starts. Pretty sure this didn’t happen the last time it ran well 2 months ago.

I did some research and found that sometimes a faulty governor can cause and engine to rev higher than it should, so I drained the oil and took off the crank case. Honestly, I’m not exactly sure what possible faults look like, so I attached a few pictures and let me know if anything seems out of the ordinary.

I also attached a video of the engine while it’s running to show you guys what it looks and sounds like. Appreciate all your help on this.

Running Engine Problemo

youtube.com

 

[OPmini]

Hi again everyone,
I’ve been trying out a few things over the last few weeks.
- Bought a new carb, but still running at high RPMs like the old one was.
- Tried on the old torque converter and that was fully engaging too.
- When I’m cranking the engine with the wheels off the ground, the wheels make a good full rotation before the engine starts. Pretty sure this didn’t happen the last time it ran well 2 months ago.

I did some research and found that sometimes a faulty governor can cause and engine to rev higher than it should, so I drained the oil and took off the crank case. Honestly, I’m not exactly sure what possible faults look like, so I attached a few pictures and let me know if anything seems out of the ordinary.

I also attached a video of the engine while it’s running to show you guys what it looks and sounds like. Appreciate all your help on this.

Running Engine Problemo

youtube.com

So the little metal flaps on the plastic governor gear move? if it is faulty it wouldn't move. Right now I see a good opportunity to upgrade your engine and add a carb with 1 cable, so you don't have to deal with this governor linkage / crap. Let me know if you do decide to upgrade, and I can help you with the right parts and setup. If you don't want to go that route I think your best bet is to put it all back together and make sure 100% that the governor linkage is set up exactly CORRECTLY. If that doesn't work and you still dont want to upgrade i'd take it to a small engine repair shop. To be honest the issue is probably something stupid that we're missing. Also I wouldnt worry about the tires turning while cranking, thats pretty normal.

 

[Denny]

I can’t help but wonder did the throttle cable slip, is the throttle cable binding is the throttle plate bent somewhere?

 

[tsimnami]

So the little metal flaps on the plastic governor gear move? if it is faulty it wouldn't move. Right now I see a good opportunity to upgrade your engine and add a carb with 1 cable, so you don't have to deal with this governor linkage / crap. Let me know if you do decide to upgrade, and I can help you with the right parts and setup. If you don't want to go that route I think your best bet is to put it all back together and make sure 100% that the governor linkage is set up exactly CORRECTLY. If that doesn't work and you still dont want to upgrade i'd take it to a small engine repair shop. To be honest the issue is probably something stupid that we're missing. Also I wouldnt worry about the tires turning while cranking, thats pretty normal.

I believe the governor is engaging correctly with centrifugal force, as showed in this video I attached.

Is the upgrade you're considering a complete governor delete? I think that might be a good idea if things are still not working correctly after trying to re-install the crank case.

I can’t help but wonder did the throttle cable slip, is the throttle cable binding is the throttle plate bent somewhere?

The throttle cable isn't attached right now. I think the throttle plate is working as it should, unless its slipping open even when the throttle is completely closed.

 

[OPmini]

I believe the governor is engaging correctly with centrifugal force, as showed in this video I attached.

Is the upgrade you're considering a complete governor delete? I think that might be a good idea if things are still not working correctly after trying to re-install the crank case.



The throttle cable isn't attached right now. I think the throttle plate is working as it should, unless its slipping open even when the throttle is completely closed.

It looks like everything is working fine unless the throttle somehow opens itself? and yes I am suggesting a governor delete, with the right engine modifications of course.

 

[madprofessor]

I could see part of the problem back in the 2 pictures of you showing how far the black plastic piece returns naturally and when forced.
Firstly: That is indeed the throttle mechanism that controls engine speed.
Secondly: The black plastic Phillips head screw you were turning is indeed the idle adjustment screw. If you backed it out all the way you'd see your low jet stuffed down into the hole that's usually covered up by the screw shank. That's how you replace it, you just pull it out and drop a new one in.
Thirdly: That piece you were showing the return on is supposed to naturally spring return until it's stopped by the tip of the idle screw. That's how the idle is adjusted, screw it in and it prevents the throttle from coming back any further, raising the idle speed. Back that sucker up.
Fourthly: What I saw in those pictures was that thin spring's straight section that hooks onto the throttle under your thumb is bent. All non-coiled parts of the springs should be perfectly straight. Bending that zigzag in it shortens it, prevents throttle from returning properly. It's part of how the governor regulates the throttle no matter how hard you floor it, and it does it with those delicate-looking little springs and such, so any change like bends will screw everything up.

 

[Denny]

The throttle looks like it is bouncing back open after you snap it closed. Forget about the black philips screw for a moment. Snug it up and leave it. Find the chrome screw with the spring around it and loosen it up until it no longer touches the spring barely. Start engine and see how it responds. It should not want to idle at all. Unless throttle is pressed. Then run screw back in slowly until idle is achieved. (Chrome with spring around it.)