Rough Idle - Dirty Carb or Something Worse?

[slomo]

From that video, she sounds great. It's only a single cylinder so maybe to you she doesn't sound perfect??? For a Briggs engine I think she is spot on.

 

[slomo]

What is that rye grass? Fine bladed shade grass seems as. That stuff cuts easy but keep the blade sharp. Mow with it.

If you really want to nit pick it, bust the carb all the way down. Remove all plastic and rubber slash O-rings and bowl gaskets. Pull all jets and emulsion tubes. Open her all the way.

Get a cheap electric single burner hot plate. Facetrash market place or new. They are not expensive at all. Water and simple green or pine sol. Take a candy thermometer and set water temp at 175F. Let her percolate for an hour. Put the jets and emulsion tube in the hot water. Plastic float and rubber pieces out remember. Make sure she is submerged. Rod her out with fishing line or the wire from a bread tie. Don't use torch tip cleaners on the jets and emulsion tube. Make sure every hole is open. Blow out with shop air and safety glasses. Put it back on and test. It might take 4 times if she is really constipated LOL.

 

[l008com]

So I played with it a little today. I have video/pics I can post tomorrow, but right now I'll just try to describe it:

Theres a lever for the choke that you can push, which will only give you a partial choke when you push it all the way. When you do, I *think* it misfires less. The RPMs are still inconsistent but it seems like it might not be misfiring as much when I do that.

As far as the throttle itself, that lever is SUPER sensitive. The RPMs are probably going up and down just from the vibrations moving that lever. When I push it with my finger, I can easily, with the lightest of pressure, lower the RPMs all the way down to nearly idle, or rev it up way past normal running RPM. Which obviously I only did for a second at a time.

I was under the impression that these engines operate at wide open throttle? But if that were the case, then pushing that lever would not have been able to make it rev higher?

I have video of all of this, while its running with me poking at it. I'll post tomorrow.

 

[slomo]

I was under the impression that these engines operate at wide open throttle?

Nope. She runs at say 3600 until she needs more fuel/air slash engine load. Governor system opens throttle in attempt to keep revs at 3600.

That lever I think you are speaking about is the governor linkage. Take a picture of your carb linkage or video what you are referring to.

 

[l008com]

So I have been thinking that the misfiring (again, the misfiring that you really can't hear on these videos but is definitely there) was causing the changes in RPM. But maybe the problem is all governor related, and maybe its the opposite, the changes in RPM are causing the slight misfires?

Anyway heres the video and me poking around with it:

Is the governor/throttle linkage supposed to be that.... twitchy?

 

[slomo]

So choking down roughly 50 percent did nothing to smooth her out. That tells me the main jet or circuit might be clogged. Next test, choke it all the way closed like you just did in the last video. You should hear it stumble down in revs. If max choke does not stumble, confirms main circuit is clogged.

Make a new video. While running, hold choke plate closed. Let's confirm this. Show it like you did in the last video. We should see stumble city. Go from choke open to slowly closed.

Next hold throttle plate slash linkage steady. Looking for steady revs taking the governor out of play for testing only. Do a low rev and a high normal rev condition.

 

[Tiger Small Engine]

There are 9 pages of posts about this mower that is worth about $100 bucks. If it is running good e

So I have been thinking that the misfiring (again, the misfiring that you really can't hear on these videos but is definitely there) was causing the changes in RPM. But maybe the problem is all governor related, and maybe its the opposite, the changes in RPM are causing the slight misfires?

Anyway heres the video and me poking around with it:

Is the governor/throttle linkage supposed to be that.... twitchy?

Nine pages on a push mower. Isn’t it good enough at this point?

 

[slomo]

There are 9 pages of posts about this mower that is worth about $100 bucks. If it is running good e


Nine pages on a push mower. Isn’t it good enough at this point?

But it will outlast all the new battery mowers out there x10.

Think we are in the polishing up stages.

 

[slomo]

Is the governor/throttle linkage supposed to be that.... twitchy?

yes

 

[l008com]

So choking down roughly 50 percent did nothing to smooth her out. That tells me the main jet or circuit might be clogged. Next test, choke it all the way closed like you just did in the last video. You should hear it stumble down in revs. If max choke does not stumble, confirms main circuit is clogged.

Make a new video. While running, hold choke plate closed. Let's confirm this. Show it like you did in the last video. We should see stumble city. Go from choke open to slowly closed.

Next hold throttle plate slash linkage steady. Looking for steady revs taking the governor out of play for testing only. Do a low rev and a high normal rev condition.

Choking down didn't seem to affect the RPMs but I feel like it did smooth out the misfiring a bit. It's hard to tell, and none of it is picked up on the camera. But I don't know, it did feel a little smoother.

Ill try that with the choke and see what I get.

"throttle plate slash linkage" . . . that what now? Also not clear on what you're actually telling me to do when you say "Do a low rev and a high normal rev condition" ??

Also note, I crashed my mountain bike yesterday and messed up my hand pretty bad so it may be a few days before I'm able to do any of this.

ALSO, second note, all forum posts are optional. You can skip any you don't like, for any reason, no questions asked. As for "isn't 9 pages enough", obviously not if the machine isn't 100% fixed yet.