Command CH 16 on Cub 2166 backfires

[xmitterengineer]

Greetings, everyone.

I've been absent awhile.

I just traded my LT 1045 (courage single knocker:thumbdown for a 2166.

The 2166 has a leak in the muffler.
I assume the leak was inspired by the engine backfiring on occasion, splitting the muffler at the seams.

The engine also was running very lean as evidenced by the spark plug being white and the engine balking on application of load.

Not knowing the lawn tractors history, I assumed a good carburetor servicing, and change of fuel filter was in order.(Walbro LMK Carburetor)
http://outdoorpowerinfo.com/repairs/kohler_walbro_lmk_carb.asp
After reassembling the carburetor (the choke linkage was a pain) it ran somewhat better, still acted lean but the backfires on application of throttle were gone.
By the way I replaced the fuel filter first, no joy found.

After the carb servicing it would still stumble a little on application of throttle.
Assuming it is still lean, I used a nibble tool to remove the stop from the idle mixture limiter cap.
Enriching the idle A LOT has stopped the stumbles, and the engine feels more powerful.
Idle speed increased to boot.
Reading the plug it still looks a little lean, not as white as before but still white-ish.

I'm wondering if I missed something?
New gaskets, new float and needle, sediment banished from float bowl, cleaned behind the welsh plug, all the external plumbing checks out.

Or maybe a little more running will color the plug to a less lean indication. (ran out of grass)

I'm thinking of modifying the main jet a little with a properly sized drill bit.
(too rich = no burned exhaust valve)
Not gonna do that until I have a spare carb or jet if at all.

Could the busted muffler affect the mixture?
I will be removing the muffler next weekend time permitting; for a date with my MIG welder.


Overall very pleased with the build quality of the 2166 Vs: the LT 1045.

Good day.

Rickey.

 

[BukitCase]

Sure, a leaking muffler can change mix by reducing back pressure - but I would be more inclined to blame "congressional gas" - for the past 3 years I've been using ONLY non-ethanol gas, and similar problems are almost non-existent. The ethanol isn't good for ANYTHING but making the Al Gore Junk Science Club feel good IMO.

I have several chain saws, 2 mowers, small rear tine tiller, Stihl hedge trimmer, post hole auger, pressure washer, backpack blower, string trimmer, 2 generators, and probably a couple I forgot - and unless the AGJSC (see above) completely outlaws real gasoline I will NEVER go back. Here's a site that'll help if you don't already know where to get the "good stuff" -

Ethanol-free gas stations in the U.S. and Canada

I read several stories of people using ultrasonic cleaners with Simple green, etc, and immersion cleaning entire carburetors for a day or two - typical claims were "runs like it did when new", or similar. So I bought one of the Harbor Freight cleaners on sale for $69, haven't gotten around to using it yet.

My point is, you may want to consider doing something like that instead of modifiying something that used to work... Steve

 

[xmitterengineer]

BukitCase,

Yes I hear you on the E-10.
I don't like political science experiments foisted on me either.

I purchased 5 gallons of E-0 87 yesterday evening for this weekends mowing.
Of course I will patch the leaky muffler as well.
I'll report back on the results.

Talked with a Walbro carburetor expert yesterday, he suggested that the E-10 problem regarding too lean mixture can be fixed with careful application of a correctly sized wire drill bit to the main jet orifice.

My take on the E-10 debacle is this:

My tax dollars went into the ethanol subsidy program against my will.
The subsidy has the end result of giving ethanol laced gasoline an unfair price advantage Vs: E-0
in the marketplace.
I will bite my tongue while buying E-10 to recoup some of my tax money that went into the product.

Thanks for your comments.

 

[xmitterengineer]

I was rained out for mowing last weekend.

However I was able to patch up the muffler which had split at the seams.
A few carefully placed hammer blows followed with some reinforcement from a wire welder and the muffler is leak free.

Afterwards; in an effort to lower under hood temperatures; I wrapped the entire muffler and header pipe in exhaust header tape.
The metal can was then reinstalled on the muffler with the aid of the wire welder.

While the front of the tractor was apart the carburetor was disassembled (again), and the main jet drilled out to the next larger wire bit size.
Being conservative, only a tiny sliver of brass was actually removed.

Since the bumper was off I straightened it and welded some reinforcing steel bar stock to the back side of it.

Now the engine is much quieter, and seems to run just fine on E10.:shocked:

The muffler housing now runs much cooler.
I can now touch it briefly without burning myself.
This has to be good for the PTO clutch, belt, and other things under the hood!

Cheers all.

 

[BukitCase]

Good to hear - as long as you're gonna use E10, you may have improved your air:fuel ratio, since straight ethanol runs around 8:1 and straight gasoline runs around 15:1 - that should put E10 at around 14.3:1 if my math is correct - it's probably a good thing you stayed conservative on the jet enlargement though, since the area of a circle is a square root funtion (twice the diameter, 4X the area) so it wouldn't take much at all to go up 0.7 (richer, that is) on the ratio.

It's possible that PART of your cooler running is that it's not running LEAN any more -

Glad it's working for you... Steve