surging kohler 16hp tractor engine

[beerguzzler50]

I have a Kohler K341 16 horse cast iron engine on a Allis 716 tractor. I have replace the points, plug, condensor, fuel filter and put on a brand new carb.

The tractor surges no matter what I do with the carb adjustments. I have verified points gap is correct. Seems to be much better when cutting grass under load--doesn't surge very much then...but it is bad when sitting or just riding. Pulled head and found valves and cylinder look normal. Onlyh other thing I can add is that when turning over to start it sometimes kicks back while starting...other than that it starts fairly easily...though it has to turn over a bit. I can see the governer working the carb, and it seems like if I disable the governer (unhook link) it will stall. This engine has the automatic compression release system for easier starting as an fyi.

This has me stumped. it doesn't burn oil or smoke either.

[Jack]

Check out the timing and then the govenor control. check the spring on govenor , if weak it can cause a surge.

[ds549]

did you reset the governor? you loosen the nut/bolt on the gov arm (the arm on the shaft coming out of the brass nut on the engine) ,turn the gov shaft ccw till it stops while at the same time holding the throttle shaft on the carb wide open.then ,lock the nut/bolt . im assuming your replacement carb is a walbro,, the high speed screw sets at 1-1/4 turn out low speed screw 2-1/2 turns out. you can download manual at kohlerengines.com for free. i find setting the points with timing light as shown in manual makes engine run cooler, but .020 gap should run ok. lucas

[beerguzzler50]

It is a Kohler carb, not the walbro (I'm positive about that). It has a idle set screw, a low idle mixture screw and general mixture screw. I'll look about how do do timing with a timing light...that would be good. I thought the timing is fixed on these engines...but I'm assuming the gap does this?

[e-mail] wrote:

[Stubby]

I just went through this with my Sear/Tecumseh. I'm fairly sure it was triggered by the E10 gas that my favorite (read, "cheap") gas station sell. Someone on this group suggested using Stabilizer (from Home Depot). I don't know what that is but it improved the situation a bit. Then I switched to high test gas plus stabilizer and things went back to normal.

In general, you must resist the urge to fiddle with all the screws. They didn't turn themselves so there is little reason to think you should tighten them.

[dpb]

[e-mail] wrote: ...

Besides the other (valid) points/suggestions, another thing that can cause surging is an air leak somewhere--like a loose carb mount, broken gasket somewhere, etc, etc. As you've replaced the carb, one of the most common has been pretty much eliminated is wear on the throttle shaft/body, but look for any other possible places. A can of starter fluid squirted around candidate places can be used to find infiltration points.

[dbuck50]

[dbuck50]

OK, I tried turning the low idle screw out...it didn't make any difference...I mean I almost unscrewed it completely and it was still surging. Here's another interesting twist...I took off the air filter (brand new and clean) and it started to stall...I hit the choke (full) and then it runs real constant?? If I back the choke off at all it stalls (WOT or lower idling). I do notice that there are very small backfires and since it was dark I would see little fire/explosions inside the carb. HELP!!

dpb wrote:

[beerguzzler50]

[Husky]

Never use "starting fluid" (or ether) on a small engine! If it doesn't burn completely, it can build up in the crankcase and do incredible damage. I prefer to use WD40. It is highly flammable, slightly oily, and it's oiliness helps seal the rings and valve guides, so it won't get into the crankcase as easily. It also used to be packaged with propane and butane as propellant, which could get into the crankcase, but usually fired better than propane and burned off completely.

Husky

dpb wrote:

[Doug Miller]

Garbage. Ether isn't going to "build up in the crankcase" or anywhere else that gets hot -- it's too volatile, and will evaporate readily.

[Rich256]

Some problems can be difficult to locate. Just a short time ago a small B&S engine was surging. The wire for the kill switch ran though a little support hole on the engine. The wire looked kind of old and when I moved it the surging changed. I put a sleeve over the wire and the problem ceased.

[dpb]

...

Thanks, Doug.. :)

That post takes the recommendation against using ether for _starting_ small gasoline engine and expands it to a generic prohibition against a completely different practice along w/ a couple of other misconceptions... :(

To jmg, yes, ether (starting fluid) should not (at least routinely) be used for trying to _START_ a reluctant small gasoline engine as it does have the potential to accumulate an excessive amount and excessive combustion pressure can occur. Even there it is certainly still a useful diagnostic tool to quickly check spark even if don't use enough to actually start an engine. And, just as an aside, I'll note that even the 3-cylinder Yanmar diesel in the little JD 955 as a proscription against ether--but the reason there is that in cool weather it uses glow plugs, not the compression problem...

That, however, is not what I suggested--in this case the engine is already running and all one is doing is using a small amount to try to find an air leak by observing whether there's a change in pitch/rpm of the engine to a minute amount being introduced through a non-desired path (otherwise known as a "leak").

As for WD40, WD40 itself is actually not very inflammable. I'm not sure what is the current propellant in the aerosals, but I suspect for the most part it is the volatile component. As an example, I've used WD40 to lubricate rusted parts, then heated them w/ a torch when they still didn't break loose and it's rare for the WD40 to actually flare even then--it sizzles and is burned away, but hardly ever even makes a real flame.