New carb but Honda HRT-216 mower runs for only a few seconds w smoke.

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  #1  
Old 06-08-12, 11:13 AM
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New carb but Honda HRT-216 mower runs for only a few seconds w smoke.

A few years ago (maybe 3) I had this mower serviced. Since then I have used it maybe 2 times but always kept the fuel drained and so forth. This year, I could not start it. It would run _VERY_ rough for a few seconds making a sort of popping noise and then shut down. The gas tank is also only a few years old

I put in a brand new carb, air filter, spark plug, oil, and gas. Then when I tried to start it, I got the same result. I did make 2 observations. 1) I get black or white smoke coming out of the exhaust. Not sure why that is (I know oil burning is white). The other thing I noticed is that on the backside of the brand new air filter there is black soot as if something is coming out of the carb and going into the air filter (valves wrong?).

Anyway, this is sort of a last resort as I don't know what more to try. Any tips?
 
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Old 06-08-12, 07:14 PM
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Sounds to me like you have valve problems, maybe even a loose valve seat. Could possibly be a partially sheared flywheel key as well.
 
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Old 06-08-12, 07:28 PM
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I had not considered those cases ... I can probably find if the key is sheared, but I doubt I could identify valve problems -- is there some trick to figuring those out?

Based on my results, I had thought that maybe the soot indicated a backfire which might show a problem with the ignition coil ... however my experience in that area is minimal so I could be way off.
 
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Old 06-08-12, 11:31 PM
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Backfiring is a possibility, which is why I mentioned valve problems and/or flywheel key. Either would cause backfiring. If the key is sheared, it throws the timing off and makes it fire too soon, creating a backfire. If the intake valve is not closing properly or the seat is loose, it will backfire combustion pressures that should be contained in the cylinder through the leak into the carb. Check the key and if nothing, remove the valve cover and see what it's looking like in there. Look for bent push rods, sticking valves, broken or cracked rocker arms. If nothing there, you might want to perform a leakdown test or remove the head and visually inspect.
 
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Old 06-09-12, 10:27 AM
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Thanks for the tips. I verified that the flywheel key is ok. In addition, I had a chance to check out my neighbor's honda mower. I noticed that mine is MUCH more difficult when pulling the starter cable. So for the potential valve problems. What is the easiest or most straight forward way to have a look at those? I have the service manual, but not exactly sure what I am looking at.
 
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Old 06-09-12, 11:06 AM
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Yours is more difficult? Then a valve problem doesn't seem as likely. A valve not seating will make it easier to turn if anything. Take the plug out and see if it has oil or gas on it.
 
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Old 06-13-12, 06:20 PM
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Valve cover off and exhaust valve doesn't move too much ....

So I finally was able to get the valve cover off. It seemed to have some sort of super sealing gasket on it. In any case, when I got it off there was oil in there.

There is a belt that looks new that was covered in oil as well as a few ounces sitting in the cover when I took it off. I went ahead and spun the fly wheel by hand to see what happens and I noticed that the intake valve (the one on the right if I face the valves) seems to open and close. The one on the left moves but only a very tiny bit, maybe 1/10th or so the movement of the right hand valve. Not sure if that tells you anything or not. I did find a youtube video that showed how to adjust the valves. Mine did not resemble the one in the video, but by observation, the ones in the video seemed to move more than mine do. I do have a feeler gauge so I could potentially do some adjustment.

I now have a new mower (just like this one) so its kind of a learning project now for me to see if I can fix it with what I learn from here, youtube, etc.

Thanks
 
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Old 06-13-12, 08:10 PM
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Sounds like you found the problem area. Now you'll need to figure out why the one valve only moves a little. Is the rocker arm loose? Is the valve coming all the way back out? I'm thinking maybe the valve guide came loose from the head and slipped, holding the valve open.
 
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Old 06-13-12, 08:18 PM
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I'll take a look and see if I can figure it out. From my reading, it would appear the oil should be there so I guess that is ok. I left it disassembled so its a little easier for me to investigate now. I think I know what the rocker arm is, but not sure I know what the valve guide looks like.
 
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Old 06-13-12, 08:23 PM
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Yes, the oil in there is normal. This is an overhead cam engine I think, so there are no push rods like I mentioned earlier, and the rocker arms look a bit different than a normal rocker arm, but they are the metal pieces that "rock" and push the valves in. The valve guide is seen through the coils of the valve spring. It's the metal sleeve that the valve fits through going into the engine.
 
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Old 06-13-12, 08:31 PM
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Great cheese! Thanks! It is an overhead cam engine (I think its a GCV-160) and what you describe looks to be what is there. A little "lever" looking thing that moves with some screws on one end that go to something inside a spring that moves in and out when I twist the flywheel.
 
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