to smoke or not to smoke?
 

guys, my 77 1200 idles extremely well with no smoke, but upon acceleration, it smokes, a dark smoke. it's not a rich smelling smoke nor is it an oil smelling smoke, maybe a cross between the two. what gives? the carb is set right. could it be rings? i'm probably gonna tear it down this winter. that's was the reasoning behind the balance gears question i posted. if i knew how to post a video of it, i would, but........... any advice or suggestions?? thanks jeff

If it's not oil smoke and it's black and sooty, the carb is probably too rich. What's the spark plug look like?

see if you can tell from here, if not i may have to wait until tomorrow, in the daylight. i really thought the carb was adjusted right, i could be wrong. i will go out tomorrow and readjust it. thanks jeff

That looks pretty good. I think I'd leave the carb alone after all. You want it a little rich so the engine doesn't overheat, and it probably is ever so slightly if there's a little smoke on acceleration. If it stumbles when you do that, try leaning the main jet 1/8 to 1/4 turn.

When you first start it does it smoke?

Are you having to added oil to the engine after a few times using it? (assuming you don't have any other leaks)

If yes then your rings are wearing out. Another sign of rings wearing is how fast the oil gets dirty. If you change the oil and within one or two uses it changes in color (gets dirty) then you are getting blow by past the rings.

If no, you may just be running rich a little.

My 14hp puffed smoke when it started and then only when it accelerated, I had to add oil after a few mowings and fresh oil got dirty quick. After the rebuild almost no smoke at starting (little due to choking) none at acceleration, oil stays pretty clean out to 25 hour where I change it (3 times so far). I have now 60 hours on the rebuild.

Picture shows the source of initial oil burn problem, top edge of piston wore and ring out of spec when measure. Cylinder bore was on high end of spec

My 122 puts out lots of white smoke upon throtel up expecialy after it has ideled for a while and I have to add oil every week. Does it need new rings ?

yeah mike, exactly like you said. i have to add oil every time i cut, it goes from the full mark to about the 3/4 mark. i was almost 100% sure it was the rings but i had to pose the question to the more qualified experts on here before i tore into. thanks guys, jeff

Ijones: I would say it maybe time for new rings etc.. if you are adding oil weekly.
Worn valve guide can also cause the engine to burn oil however, it seems to be not the leading cause in these engines.

Jeffscub: There are many good treads here that will help guide you this winter as you take things apart. (I did a write up called 1450 Makeover here may help) Do a lot of reading and take alot of pictures before you start.

You will also notice a good difference in the engine after a overhaul, when you are done you will have a great little machine to be proud of for many years to come!

Hmm.. two of my Cub Cadet's have similar problems. (One smokes when hot, the other makes a little puff at startup and when turning up the throttle fast.. both use a little oil)

Did you replace the piston too or just the rings?

That depends on the condition of the cylinder wall and piston. If your cylinder walls are clean and in specification after a light honing and there is no scoring on the piston, you could get by with the same piston.