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KSever

Too Rich or Too Lean

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KSever
Installed the new Kohler carb on the 14HP Kohler today after I got it in the mail. Problem I'm having is I get a little and I say a little smoke which I never had with the old worn out carb. That old carb would just not run right and backfired all the time. I'm thinking it's in the carb tuning but which way am I off too rich or too lean? It runs good if I tune it either way but I never noticed the little bit of smoke until I was out tonight trying out the lights on the cab.. Or could it be just because it's cold outside?

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MPH
Probably hard to tell out in the dark, but if the smoke is black, your too rich. How cold is it out Kris? I have found I need to richen mine a bit when I'm foolish enough to go out at 20-30 below.

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BLT
MArty is right. Check this condition in the daylight. My guess it is the idle screw that is a tad too far open. Run it at WOT under load and observe it. That is where it realy counts.

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Al
Hi, If the carb has a high and low speed adjustment, warm the engine up and run it wide open, preferably with a load on it. Adjust the high speed needle for the absolute best running. I always watch the throttle linkage. The governor will "hunt" just a little until the mixture is perfect. Next I open the needle just a little until you can detect a slight "ever so slight" change of pitch. Then move it back in until that starts to leave. At this point you have the main jet where it should be. Next I idle it down and go to the throttle stop screw and slow the idle as slow as it will go. Then I adjust the idle to where it idles the best. Next I open it wide open and readjust the high speed jet as above. Next I idle it down and recheck the idle. Then I open it wide open, if there is ANY hesitation on acceleration, I open the idle jet a little and check it again. After the final idle adjust I readjust the main jet. Then I slow it down and set the Idle speed where it is supposed to be with the idle stop screw. ALWAYS MAKE THE HIGH SPEED ADJUSTMENT THE LAST ADJUSTMENT. If this is too lean this it what causes overheating and piston scoring, holes burned in the tops of pistons, etc. especially on 2 cycles. The idle mixture adjustments have a slight effect on the high speed mixture, so this is why the high speed adjustment should be last. The high speed adjustment should always be on the rich side of where it runs absolutely the best. Note: This is no longer true on the newer lean burn chain saws and string trimmers, as they have a maximum rpm spec and the carb is to be richened not to exceed that or cylinder scoring will likely occur. My 2 cents worth and its free, value accordingly. Al Eden

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KSever
Thanks Marty, Bob, and AL for the response. A well lesson learned tonight, I will have to go out tomorrow and warm this engine up and tune it the right way as Al explained in detail. Oh Marty it's cold here tonight about +20 :D Not your kind of cold, eh?

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JoeJ
Al, This may be a really dumb question, but how do you put a load on the engine while doing the adjusting? AND, thanks, I'm going through the same problem on a 10 HP. So this thread hit at just the right time. :D(printed and stuck in the Kohler book)

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MPH
Well Kris, what color did it smoke in daylite? Because of this post I paid attention today at -20 on how bad the Landlord was smoking white. Know it was more steam affect then smoke, but never paid much mind to it before, just took it as normal.

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KSever
Never got to really try it out Marty (sorry for the wait) but I spent almost all the daylight hours at Church of the Farm and Fleet, then Home Depot. I'll try again tomorrow but don't wait up and leave the light on.

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BigSix
Al: Awesome post on carb tuning! I did much of what you do, but I only had a rough idea of why I was doing it. I have never read any treatment of this subject that made things so clear for me, but I should be used to this, from you, by now. I too am printing it for future reference. I'm leaving town for a while, but when I get back I've got to find out what caused my buddy's Wheel Horse GT 14 to lean out, suddenly, and die. I see sediment in the clear, new filter, so I suspect a blockage, but I think I will take that opportunity to retune that carb. I recently rebuilt it, set the idle with a tach, etc.... It ran great until yesterday, with the sediment, which I think is actually killing the fuel supply before it even gets to the (new) filter, as the filter is not half full of gas, like normal. I also notice air bubbles rising in the gas line, to the carb (Kohler 321/14 h.p.). That strikes me as abnormal? So we shall see. Btw--this engine appears to have a fuel pump--if so, are they vacuum driven or mechanical? I didn't take the time to to look, as it was cold and dark then. Thanks again. Peter

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