M-18 running rough/missing

[farmall fred]

John, the $5.00 paint job looks great. As far as running it on the bench it is easy on a Mag 18, the last on I worked on I started it on the bench a couple of times chasing down a miss before I tore it down and also after I reassembled it so I could retorque the heads. Just as ol'George said a hose in a gas can and a jumper cable to the starter. after running just ground the kill wire to tghe mag to sut down. I would hate to see you scratch up that fresh paing putting it in and out of the tractor. As far as retorqueing the heads it is a must in my book. Run the engine long enough to get it warmed up good and then after a overnight coo down torque them again. The K341 I just replaced the head gasket required almost 1/4 turn on the head bolts when I retouqued it. In the end do what is easier for you. Good luck on the first start up.
Later
Tom

[yeeter]

Nice!

Where do I get me some of that paint?

What brand is it?

And how much does it cost?


(zip is a bad influence...)

[john hall]

Well, my $4.98 paint job did NOT solve the miss in this engine. We had a moment tonight to finally stick it back in the Cadet and crank it up. SAME PROBLEM, one cylinder appears missing--its running on that side but missing a LOT. As best as I can tell its the right side (if you are sitting in the seat). It started within seconds of cranking and is noticeable throughout the RPM range. I pulled the plug wires one at a time and you can tell the right side isn't pulling its share of the load. Also, thermometer shows that side running much cooler--was able to focus it around the head near the plug (heads beadblasted when I had them off). Just a recap, thought the carb needed rebuilding, as the PO had someone try to do that. Put a kit in the carb, still missing. Found the spark stronger on one side than the other, replaced the coil. Checked valve clearances, everything was more or less in spec--one side at least had been into by somebody before I got the Cadet. Sprayed carb cleaner all around the intake looking for a leak, no luck. Tried old plugs, new plugs, maybe even crossed the wires side to side, no luck. Decided the valves needed grinding and cleaning. Had a shop do that, I put in new piston and rings (learned my lesson on ring gap with this one). I ground the valve clearance upon reassembly, per the book.

At this point, I'm basically starting over. Next time I have a chance to look at this thing, I'm going to check compression again (originally it was fine), check the strength of the spark on each wire, maybe cross the wires to see if the problem moves. I did run it in the dark tonight to see if I had a damaged wire, didn't see any sparks. If all that checks OK, I've got a blown KT I can steal the carb off of. I swear I checked the intake for an obstruction--but as of now, I may have forgotten to. I'm wondering if the last guy to open the carb tried drilling the jets or something? Is it me or is one side of the intake longer than the other? Maybe he monkeyed with the carb enough that it isn't metering the fuel correct and if the intake is longer on one side than the other---I know, I'm grabbing at straws here.

Oh yeah, pulled the choke on till it blew smoke, slowly pushed it back in, still missing.

The list of new parts---plugs, coil, carb kit, fuel pump, piston and rings, valve job, and of course gaskets and seals. Heads were faced and lapped and torqued.

Talking crazy here, but I have heard of engines running with broke cranks, could this thing have a broke camshaft? Seems if that were the case then one side would be a constant miss.

What simple thing am I missing here?

[ol'George]

John,
The Cams that break are caused by a rod breaking them, not on their own.
You can try the other carb, why not? you have done most everything else.
When you done the initial compression check and it was good, I didn't think it was valves but I'm always open to learning.
Is the carb on it now, the adjustable kind?
The one from the KT should be adjustable.
Try it,you might get lucky there and adjust it so it runs fine.
As far as right/left side,it is almost always viewed from the operator position.
Did you check the intake manifold for an obstruction on the R side like a dead mouse or stuff?
At this point we all are grasping @ straws.
And yes, do run another compression test just for a base line.
If the carb swap produces no joy, then remove the muffler and try running it.
somewhere we all are missing something.
Those things run sweet.
Do not give up!!!!!!!

[john hall]

Carb on it is non-adjustable. I THOUGHT I cleaned it well when I rebuilt it?? Likewise, I think I checked the intake for an obstruction. I'll certainly start with basic checks like fire and compression and progress slowly and methodically. I love the M20 in my 2072, hope to get this one to run just as well.

[john hall]

Well, to cut to the chase--it was the carb all along. After checking the basics--fire, compression--we pulled the fixed jet carb back off and pulled it apart. Can't see anything wrong, didn't notice anything modified, just doesn't make sense. I had 2 KT engines--series 1 and 2. The series 1 had a fixed jet on it, but it had been left out in the rain--I think I can salvage the screw and clamp for the choke cable, that's about it. The series 2 had an adjustable jet carb. I pulled it off and started cleaning it out--had been sitting with fuel in it for several years, began to turn to tar. Took it apart, cleaned it out, used over all the gaskets---because I did not have a kit. Put it on and dang thing fired up. Opened the main about 3/4 and closed the idle jet a pinch--runs fantastic.

I'm some where between relieved, happy and disgusted. Relieved because I'm tired of working on this one, happy because it runs well, disgusted that I didn't give this a try before opening up the engine. Now given the hours on the tach (1700---I really don't think there is that many on the machine or the engine), I'm not upset we put in pistons and ground the valves. Valves had wear as well as the pistons were showing wear also. I do have an oil line leaking I need to address as well as torqueing the heads again. Maybe there is a light at the end of the tunnel after all.

[ol'George]

Originally Posted by john hall

Well, to cut to the chase--it was the carb all along. After checking the basics--fire, compression--we pulled the fixed jet carb back off and pulled it apart. Can't see anything wrong, didn't notice anything modified, just doesn't make sense. I had 2 KT engines--series 1 and 2. The series 1 had a fixed jet on it, but it had been left out in the rain--I think I can salvage the screw and clamp for the choke cable, that's about it. The series 2 had an adjustable jet carb. I pulled it off and started cleaning it out--had been sitting with fuel in it for several years, began to turn to tar. Took it apart, cleaned it out, used over all the gaskets---because I did not have a kit. Put it on and dang thing fired up. Opened the main about 3/4 and closed the idle jet a pinch--runs fantastic.

I'm some where between relieved, happy and disgusted. Relieved because I'm tired of working on this one, happy because it runs well, disgusted that I didn't give this a try before opening up the engine. Now given the hours on the tach (1700---I really don't think there is that many on the machine or the engine), I'm not upset we put in pistons and ground the valves. Valves had wear as well as the pistons were showing wear also. I do have an oil line leaking I need to address as well as torqueing the heads again. Maybe there is a light at the end of the tunnel after all.

There you go, KISS -----keep it simple.
Great news and
Congratulations
You have a good engine you know has new rings,pistons & a valve job.
You learned a lot.
That is worth the time and $$ you spent.
Some paint pictures, some carve wood, still others play sports, all give satisfaction just in different ways.
There is nothing that gives me more satisfaction, than fixing that which malfunctions.
I cut grass today with an M-18 I built from parts and a converted vertical block.
A heck of a good feeling, and if I have to explain that, they wouldn't understand.

[john hall]

Re-torqued the heads this afternoon, they moved maybe 1/8th of a turn. FWIW, you can do it with the engine in the frame and without warping the shields over the heads--we left the bottom bolts in them. It took a little effort to get on the #9 bolt (torque sequence), but I managed and the covers didn't get screwed up in the process. Ran the Cadet for about 30 minutes, drove it 1/2 mile.

[zippy1]

Good the hear you got it going John. Sorry you had to go through all that extra work to get the end results though. I feel your pain...
Just put the engine back in my 1811 after going through it replacing gaskets and seals.Went to start it, "CLICK,CLICK", oh, duh, forgot that the starter was bad, and was going to replace it when I had the engine out.
SO, had to take it back out, and ordered a new one, now I'm back where I started, with a 1811 with no engine in it.

[Oak]

I'm glad it is running well John and this was a great thread. I like the Mag engines so I learned a good bit of info on your adventure. What's next?