Engine de-surge?

[rondo 0]

My B-100 with the K241 started running a little funny today (it actually did this once before about two weeks ago but it smoothed out pretty quickly) after it had been sitting for a little while. Here's the issue:

It starts up right away with it choked (as always) and when I cut the choke it runs fine at fairly high idle...for about a minute or so. It then starts to sputter and Idle right back up, over and over. It idles fine, for varying lengths of time, then it idles down very briefly, kind of sputtering, and idles back up again. I ran it for a long time thinking maybe it was a little cold. Didn't seem to make any difference - it's almost like I'm cutting the throttle and then boosting it again...but I'm not.

Checked the plug and it had a lot of carbon so I cleaned it up (but I'm getting a new one tomorrow) but it didn't make a lot of difference. I did notice that my choke seemed to be creeping up and it seemed to run better when I forced the choke handle all the way down.

I have a cheap little push mower at a little cottage with a small Briggs that does this same surge almost every time that I use it. The plug in that one gets carboned up pretty quickly too.

Could it be that the Horse is running rich? I don't know if that would explain the surging (actually de-surging), but I'm kind of confused. By the way, I just picked up the Horse in August but it has always run really well until just lately. Anybody familiar with this surging thing?

Any help appreciated.

[MaineDad 85]

Mike,

I have been having a de-surging issue too. Mine ended up being a carb problem. Specifically the float was not working correctly. The float needle was not seating allowing too much fuel (rich) so it would surge at low idle. Maybe the same problem you have?

[Jim_M 178]

You mentioned the choke is creeping up, if I understand you correctly the choke is closing on it's own. That would be a problem. If you choke a warm engine it will be running way too rich.

If your plug is black and sooty you're running rich. I would try leaning it out a bit and see how it runs. If that doesn't do it, you might want to check your float setting.

It could also be a combination of the choke being on and the carb being set too rich.

[rondo 0]

Well guys, just an update. Changed the plug and leaned it out a bit - made a bit of a difference. I did notice though that when it idles down and I give it some gas, it does seem to blow out a very small amount of black smoke, every once in awhile. It's running OK but I think I'll check the float because it still seems a little rich, at least sporadically.