Craftsman Push Mower Misfiring

[KE4AVB]

Surging is different than miss firing. First hard cranking on a l-head can be valve clearance are too closed up.

Once you get the engine started trying holding the throttle still and see they surging goes away. IF it does it might that the idle speed is set too low. Otherwise it a governor problem if it runs smooth.

[Merkava_4]

Surging is different than miss firing. First hard cranking on a l-head can be valve clearance are too closed up.

Once you get the engine started trying holding the throttle still and see they surging goes away. IF it does it might that the idle speed is set too low. Otherwise it a governor problem if it runs smooth.

Now that you mention it, you're absolutely correct; there is a difference between a misfire and surging. The engine was surging so badly, I couldn't tell if it was misfiring. I think I'm at the point now that I'm going to start the disassembly process and begin a rebuild. Eliminating all the variables is the approach I like to take. I'm going to take my time and get all the parts real clean. I was surprised by the IPL not listing any oversize pistons or piston rings. I guess that means that if the cylinder doesn't pass the ring gap test, a new cylinder assembly has to be ordered up. I wonder how much different the bore is from all the other models that have oversize rings available. I wonder if the standard size chrome ring kit I used for my horizontal engine would fit this 10M902.

KE4AVB, do you recommend a compression tester? I see that Briggs & Stratton only offers the leak down type. That requires shop air that I don't have. I'm looking for a simple compression tester that I can thread into the spark plug hole and turn the engine over with a drill.

[KE4AVB]

Surging is different than miss firing. First hard cranking on a l-head can be valve clearance are too closed up.

Once you get the engine started trying holding the throttle still and see they surging goes away. IF it does it might that the idle speed is set too low. Otherwise it a governor problem if it runs smooth.

Now that you mention it, you're absolutely correct; there is a difference between a misfire and surging. The engine was surging so badly, I couldn't tell if it was misfiring. I think I'm at the point now that I'm going to start the disassembly process and begin a rebuild. Eliminating all the variables is the approach I like to take. I'm going to take my time and get all the parts real clean. I was surprised by the IPL not listing any oversize pistons or piston rings. I guess that means that if the cylinder doesn't pass the ring gap test, a new cylinder assembly has to be ordered up. I wonder how much different the bore is from all the other models that have oversize rings available. I wonder if the standard size chrome ring kit I used for my horizontal engine would fit this 10M902.

KE4AVB, do you recommend a compression tester? I see that Briggs & Stratton only offers the leak down type. That requires shop air that I don't have. I'm looking for a simple compression tester that I can thread into the spark plug hole and turn the engine over with a drill.

You must be looking at a different IPL. The IPL from the dealer site has a piston .020 over PN 792532 (includes rings). Standard bore is 2.560. Also highly suggest using a rigid hone as if the cylinder is taper and/or tapered a flex hone just makes it worst.

I use an Actron one here that is designed for small engines. Basically you one with the schrader valve at the end of the hose. Also you need to get the engine up to 500 RPMs at least to disable the ACR on the camshaft. Normal recoil speed has to be at least 350 for the coil to trigger. The closer to normal speed the better if you try a compression. Otherwise you be getting a reading of 70-90 Psi on a good engine when the ACR is operating.