M-18 running rough/missing

[john hall]

Originally Posted by Mike in SD

This is where I bought my Genuine Kohler mag coil when I needed one. I have had very good luck with Pats Small Engine.
http://www.psep.biz/store/kohler_52_...ition_coil.htm

HTH,
Mike

Great price!! I found one other place around $100. Even some aftermarket ones were approaching $130-40. I will say I was not impressed with the aftermarket one I got. The wire ends were not on it. No big deal to slip the boots on, and install the wire ends. I spent 15-20 minutes trying to get the ends back in the boots--they just weren't made big enough for the style end supplied. I screwed one up and had to replace it--the ones I had were a little heavier. Next go around I'll probably spend the extra cash and buy Kohler. Evidently I'm not the only one with issues installing the ends, I saw a couple comments in reviews for online sales.

[john hall]

Cranked it up today to check the new coil, it's still not running that great. Maybe a little better, but far from what it should be. Alternated pulling plug wires with it running for a few seconds. Right side backfired once when I hooked it back up, it did that last time I tried this with the old coil. Maybe a connection with what I found when I pulled the valve covers to check clearances. Some body has been in there, found the mesh matl from the breather in with the valves instead of on the other side of the reed valve! I checked valve clearances, left side intake .003, right side around .008. Both exhaust around .01-.012---appears right for the ser# break. I plan on trying some Marvel Mystery oil to try to free up a sticky/lazy valve. Outside of that, time to pull the heads and see if I can find anything else weird or do you guys think this is carburetor issues? I hate these types of problems that can be anything. Only thing I am sure of right now is I have good strong spark--both firing about 1/4" simultaneously with my tester. Yes the fuel is fresh and the plugs are new (acted up with the old ones as well).
Anyone want to throw a dart at the wall? How much trouble is it to put a KT17 carb on it? I have one that hasn't been used in 10 years....

[Terry C]

Originally Posted by john hall

Cranked it up today to check the new coil, it's still not running that great. Maybe a little better, but far from what it should be. Alternated pulling plug wires with it running for a few seconds. Right side backfired once when I hooked it back up, it did that last time I tried this with the old coil. Maybe a connection with what I found when I pulled the valve covers to check clearances. Some body has been in there, found the mesh matl from the breather in with the valves instead of on the other side of the reed valve! I checked valve clearances, left side intake .003, right side around .008. Both exhaust around .01-.012---appears right for the ser# break. I plan on trying some Marvel Mystery oil to try to free up a sticky/lazy valve. Outside of that, time to pull the heads and see if I can find anything else weird or do you guys think this is carburetor issues? I hate these types of problems that can be anything. Only thing I am sure of right now is I have good strong spark--both firing about 1/4" simultaneously with my tester. Yes the fuel is fresh and the plugs are new (acted up with the old ones as well).
Anyone want to throw a dart at the wall? How much trouble is it to put a KT17 carb on it? I have one that hasn't been used in 10 years....

Ask Tim. I sold him one off a Kt17 awhile back. I think it's not a big deal.

[REDDHOGG]

Spray a little water around intake while runnng

[john hall]

Originally Posted by REDDHOGG

Spray a little water around intake while runnng

Never heard of using water, what's the idea?
I have sprayed it heavily with carb cleaner (couple different types) trying to find an intake leak--no luck.

[Mcamp]

kt-17 carb is the same,is better because of adjustable jets.

[2009Dodge]

Is it still mis firing? Back fire when you put the plug wire back on is normal, exhuast will load up with fuel and ignite when you reapply the fire. I'd do some more trouble shooting with the carb or timing.

It's good the coil is fixed. Weak spark will magnify underlying problems. Is it running rich or lean? If you apply a little bit off choke does it kill immediately or fight a little bit? If it dies immediately it's getting to much fuel. If it runs smoother and more responsive it's starving for fuel. Are both exhaust ports getting hot? Check with a non-contact thermometer or spray both sides of the manifold with water and see if sizzles off.

Do what j-mech says! That guy seriously knows his stuff! non-adjustable carbs suck

Just trying to help. These guys are better than me at this trouble shooting thing and may have some tips!

*edit* make sure the fuel pump is working

[J-Mech]

John, your better off taking it apart and cleaning the valves than you are trying to get it to free up with MMO. It's not a big ol' motor that takes hours to tear into.... just pull the heads and valves and clean it up.

As far as it being carb related... it's a single carb on an open manifold. Unless something is blocking the flow in the intake, it can't run good on one cylinder and not the other unless there is a valve issue. (You've eliminated ignition and it sounds like you have tested for intake air leaks.) Time to take it apart bud.

[john hall]

Playing with the choke doesn't make any difference. I didn't pull the plugs back out today, last go around we could certainly tell a temp difference in them. The backfiring seems strange to me because it only happens on one of the cylinders. I'll probably pull the carb off the KT and give it a try later in the week--hopefuly that carb is in decent shape.

I've found too many weird things with this mower that are making me concerned:
a 1/4" bolt stuck in the fuse holder
fuel bowl had been reinstalled with some sort of glue (really good stuff whatever it was) but no O-ring.
The breather matl was laying on the valve spring--and was on the wrong side of the breather plate (reed valve)
2 of the engine-to-mounting plate spacers were missing.
Wiring harness was sliced and diced with an auxillary wire to solenoid just to bypass the pedal switch--why not make a jumper wire, less work.
PTO crank seal installed way crooked
The guy I got it from had paid someone to "work on the carb"

Anyway this type of work has me wondering what else weird could have been done wrong. The weird part is the machine isn't beat or banged up or no crazy modifications, just some mechanic work causing me to scratch my head.

Thanks for the ideas thus far, I'm listening to them all believe me. Checking the cylinder temps then swapping carbs are probably the 2 things next to do. After that, pull the heads to see the valves?

[J-Mech]

Originally Posted by john hall

Checking the cylinder temps then swapping carbs are probably the 2 things next to do. After that, pull the heads to see the valves?

See post #18.

TAKE THE HEADS OFF. Skip the carb and cylinder temps. We KNOW that one of the cylinders isn't working right.... like you proved it 3 or 4 times now.