Engine won't idle

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panofish

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Jun 9, 2009
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I've read dozens of threads, but I still feel stumped.
Here are list of symptoms for my new build:

1. Engine starts with medium choke and slight throttle only
2. Must hold slight throttle and feather choke to keep engine running
3. Engine will rev with throttle, but is rough at times (because it is choked)
4. If I release throttle then the engine dies immediately
5. If I turn choke completely off then the engine gets weaker and weaker until it dies
6. Adjusting the idle screw has no effect

My best guess is a vacuum leak between the carb and intake?
 
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Goat Herder

Goat Herder

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If its a Chinese a stroke ? Just turn the screw clock wise on the left side of the carb. Its the one with a spring on it. Just let us know if you need more help . Welcome to the forum !
 
Goat Herder

Goat Herder

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What kind of engine is it maybe one of use can help more. Don't worry lots of help here you will get help! soon.. Have you let the engine warm up?
 
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panofish

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Jun 9, 2009
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OK... I disconnected the fuel line from the tank and opened the petcock to drain the fuel.
The fuel drained out slowly in about the thinnest stream of fuel possible without dripping. How fast should it have drained?

I would have thought it would drain as if through a thin straw. I removed the petcock... the filter above the petcock looked clean. So the thin flow of fuel was caused by the filter screen, a smaller orifice inside the petcock valve, or something else inside the petcock?

Tomorrow, I will try running the engine with the fuel remaining in the the fuel line (unattached to the fuel tank) to see if there is any difference.
 
Goat Herder

Goat Herder

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Try tacking the gas cap of the tank. If flow speeds up ? You will need to drill a pin size hole in the center of the fuel cap to vent it!
 
Goat Herder

Goat Herder

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You are clogged somewhere It should make a darn messy puddle quickly! It should flow faster than that . The petcocks clog up very easily , when trash gets to them. Are you sure the screen in the tank is not clogged? They fall apart very easily too! That will clog the petcock. If your kit did not come with one do get a in line filter. I had a fit with my set up . I did away with the tank filter . Then I used a swamp cooler water cut off valve it has a bigger orifice flow channel to it. But thats just me.
 
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panofish

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Jun 9, 2009
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The screen looks like a very low quality plastic mesh, but isn't clogged
The screen unscrews easily from the petcock.
I disassembled the petcock and found no clog.
The internal holes are smaller than the fuel line connector, but I would still expect a faster flow.
Tomorrow, I will reattach the petcock (without the mesh screen) and add some fuel to the tank and check the fuel flow.

 
Goat Herder

Goat Herder

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Get a in line filter perhaps bypass the petcock temporarily . See what that might will do . There was one form of petcock a brass one I had seemed like when I took it apart I accidentally re clocked the innerds I cant remember Anyway you should have better fuel flow than that . Sorry I could not help. You will get more input from others soon! LOL
 
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panofish

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Jun 9, 2009
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Fuel flow was still a trickle when I removed the petcock screen, but I don't think that is the problem.

I added an o-ring between the carb and the intake and that made little difference.

I was able to take a short ride today, here are the symptoms:

1. I had to keep the throttle at 5%.
2. If I released the throttle then the engine dies
3. It I try to increase the throttle then the engine bogs down and loses power.
 
2door

2door

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Sep 15, 2008
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Not to dispute my old friend Goat Herder, but I wouldn't be concerned about the fuel flow you've described. If it flows, it's enough. Think of it this way: Consider the advertised milage of these little engines, even if you get half of what is promised think how little fuel will be flowing to your carb. The symptoms you're describing sound more to me like an air leak in the intake manifold or carb. The carb should be sealed to the manifold with a good grade of silicone gasket sealer/adhesive. Fill those little slots in the carb throat, coat the manifold and slide the carb on and tighten it. Same for the manifold flange where it bolts to the cylinder. Any air leaks in those areas will cause a lean condition which will give you the symptons you describe. If you think there could be air leakage at the carb/manifold, try spraying some carb cleaner on the area, even WD-40 will work, and around the magneto cover and where the wires come out from the engine. An increase in RPM will tell you if there is an intake leak or in the case of the magneto cover, if the crankshaft seal is bad. Bad seals are rare but no unheard of. Are you seeing any signs of an exhaust leak at the cylinder where the exhaust pipe attaches? A bad enough leak there can also allow air to be drawn in causing some abnormal running conditions. Give these things a try and get back to us.
Tom
 
reg454

reg454

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POst a pic of where your carb needls clip is.

Have you tried adjusting the carb needle clip to make your motor more rich like lowering it 1 notch. If you have to keep the throttle open a little bit then your motor is not getting enough gas. try that it only takes a minute to try.

Be safe out on the road
 
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panofish

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Jun 9, 2009
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Actually, it has never run "fine", but it has been running if I hold the throttle at 5%.

I think the next best thing is to open the carb and check and clean it carefully.
 
Goat Herder

Goat Herder

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Do the simple stuff first 2Door mentioned spraying carb spray. That is a quick and simple thing to do. Stock needle clip placement should be second notch down from the top of the needle. Let us know?
 
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panofish

New Member
Jun 9, 2009
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Michigan
PROBLEM SOLVED!

I finally opened the carb and guess what I found?
The brass jet was totally unscrewed and just flopping around in the bowl.

I screwed it in place and now she runs and idles like it should.

Wow, this thing puts out a little more vibration than I'd like... maybe she'll run smoother as she breaks in.

I shot video of the entire build process (including the problems) and I will post it on my blog when I have it edited. I am going on a 2 week vacation next week, so it will be a while before I can finish the video. I think it will be the BEST video you can find on this subject. :)
 
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eugesd

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Jun 7, 2009
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Does it really matter
panofish said:
PROBLEM SOLVED!

I finally opened the carb and guess what I found?
The brass jet was totally unscrewed and just flopping around in the bowl.

I screwed it in place and now she runs and idles like it should.

Wow, this thing puts out a little more vibration than I'd like... maybe she'll run smoother as she breaks in.

I shot video of the entire build process (including the problems) and I will post it on my blog when I have it edited. I am going on a 2 week vacation next week, so it will be a while before I can finish the video. I think it will be the BEST video you can find on this subject. :)
Click to expand...
can you explain exactly what you did, since im having issues with this too
 
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