If yours has an adjustment, it is located on the front of the carb w/ a spring around the screw. A tad out may help. Are you saying that holding the choke out helps keep it running? Or does it shut off when it gets warm? Be sure that the fuel cap is venting as well. Should you need to give the carb a quick clean, I like to leave them mounted and just pop the top.

It doesn't seem to matter if I choke the engine or no, the engine slows under a heavy load for instance if I go through a patch of tall grass. If I stop the engine will come back to life. It hasn't always done that.

This is typical of the engine only running on one cylinder. Have you checked that?

Walt Conner

What would be the easiest way to check that?

Put the spark plug wires on loose, pull one at a time and see what happens, should be about the same amount of drop off when each one is pulled.

Walt Conner

Apparently you were correct. the engine dies when I disconnect the right side. I pulled the plug and I do get a spark. What next? Thank you for your help

was reading this thread about a dead cylinder. Will have to invest in some feeler gauges. These are what you would use on spark plugs as well, correct?

You may want to remove both spark plugs and hold your finger over each spark plug hole and see if it is blown off when you run the starter. Put spark plug wire where you won't unintentionally "test" the spark.

You may have thrown a rod or, with that engine, perhaps more likely a valve seat came out usually caused by the cooling shroud/fins being plugged up and not getting cooling.

Walt Conner

The valves seem to seal pretty tight, how do i check the seats and or remove the valves?

"The valves seem to seal pretty tight, how do i check the seats and or remove the valves?"

Getting ahead of our selves. You didn't answer my question about blowing your finger off the spark plug hole and how do you know the valves seem to seal pretty tight? IF you have the head off, is the piston going up and down?

Walt Conner

Yes I have the head off and the piston is moving. I had replaced the sump gasket and put the engine back together prior to having this problem. After putting the engine back together the engine would not start, needed to reset the timing. Put the engine back together, and it started right up. And as I said it wanted to stall once I started to mow.

" Put the engine back together, and it started right up. And as I said it wanted to stall once I started to mow."

These engine will run quite happily on one cylinder but don't have the power.

Is there spark on the non-running cylinder? This is a single coil engine but I have heard of one side going bad.

You tell if a valve seat is loose by looking at the carbon around the valve seat. IF the seat is loose, there will be a sharp, distinct, line around the outside of the seat. IF it is tight, it will be pretty much carboned over.

Dont' see where you relaced the spark plug on that cylinder.

Walt Conner

i would definately consider it tight then by your explanation.
WHere is the coil located, under the engine shroud?

Yes.

Walt Conner

I have the shroud off. Is the coil a little half moon shaped thing mounted next to the fly wheel?

Yes! Check the coil. See if it is rusty at the ends of the coil legs, where they sit close to the flywheel. While you are in there, clean the coil legs and flywheel steel parts with sand-paper. If you remove the coil-then reset the gap with a business card between the legs and the flywheel. Sound "fishy"? T'aint! We do it that way!

It is the coil. I found enough extra spark plug wire to have it reach the side that wasn't working. Installed the known working wire and she fired right up. Just need to order the part.
Thanks for you help

My apologies for hijacking this thread but i'm dead on topic.

My 42a707 overheated as you said (from a critter's nest)and i lost the intake valve seat on the left side (facing the front. Which cylinder is that?). I hired a local shop to replace it and it FELL out while running. I know this cause I pulled the head and i can see it just dangling from the valve stem. It's still intact but it scored up the area where it's supposed to be set in as the valve was banging against it.

I also can see where they peened the exhaust valve seat. It's still in place.

My question, is there a way for me to place that seat back in myself.

Thanks!

If you are referencing the left cylinder as sitting in the operator's seat (which is the correct standard) that is cylinder #2, by Briggs nomenclature. If you are standing in front of the tractor looking at the front of the tractor (incorrect ref point standard), the cylinder on "that left", is #1 by Briggs.
As to repairs in DIY mode. Doubtful you will achieve lasting success. A very competent automotive machine shop would have a much better chance of resolving the issue. In a severe overheat situation, even the geometry of the block can change. And it only takes a little bit of warp or elongation of the valve seat bore to produce a condition where the block simply does not want to hold onto the valve seat. A good automotive machine shop can overbore the block to fit an oversized seat (which they will have to make or obtain) and install the seat or seats properly. The punching and peening technique to reseat a loosened valve seat only works if the seat has simply gotten "loose" in the block. If the seat has actually upchucked from the bore in the block, there is just too much damage to the bore and the valve seat for it to ever be trusted again.

Mighty kind of you to reply, thank you. I love this tractor, would you have a loose, ballpark guess as to how much that would cost (the machining overbore and new seat? I'll happily spend $100, maybe 2 if i could get it back.

Thanks mownie!!

I couldn't say for certain what the cost would be. You will have to poll some machine shops in your area to get a feel for the prevailing rate. Automotive machine specialist type shops will be the best to check with as they have the equipment and expertise to handle a job like this. To them, it's actually an everyday event to cut a cylinder head for oversize valves in the quest for more power. Doing the same to an engine block (in your case) to correct for damage is not all that different, for them.

On horizontally opposed B&S twins, the cylinders are offset. The cylinder closest to the flywheel is the #1 cylinder.

Walt Conner

***"The cylinder closest to the flywheel is the #1 cylinder."***
Thanks Walt, that is consistent with what I found.
Do you know if the same rationale is used on the Vanguard V twins?

You's two are a wealth of knowledge, Thanks!

Ok replace the coil. Pulled the wire on the "good" cylinder and the tractor died again. Put the "good" wire on the "bad" cylinder and started right up. Other being a bit confused I'm just getting a bit miffed. Another help you can give?

How do you replace the top crankshaft bushing on a Model 42a707?

My lawn mower wont stay running when the gas tank get half empty. I changed the fuel filter and the fuel line. When it starts to stall I look at the fuel filter and there is very little gas in the filter. I have also have made sure the fuel cap holes was open. Any ideas thanks

Which lawn mower and which engine do you have?
Can you confirm that if you immediately refill the fuel tank that you can once again use the mower continuously until it again drops to half a tank and quits?

Hello I need the torque specs for the rod caps and heads for a 42A707 type 2653E1 17 horse briggs engine . Can anyone help?

I can send you a complete Service Manual for your engine if you like. Address below, put in proper format and remind me engine model and what you want.

Walt Conner

wconner5 at frontier dot com