The PDF service manual is for a 40777 model 20hp B&S Intek, and what I found on the air shroud is 4067770128E1 under a barcode and also on the other side of the engine air shroud by the emissions information - Family YBSXS.7242VF 274844. Is one of these the model number? Copy / pasted from the PDF: "Avoid damage! Exhaust valve push rods are aluminum. Intake valve push rods are steel. Mark push rods for identification with tape or tags to prevent interchange." The aluminum pushrod was on top, and that valve goes to the carb, the steel pushrod is on the bottom with a red marking on the rocker arm bolt, which is the exhaust. The aluminum pushrod has a very slight bend to it - can't tell looking but rolling on the steel one I can see a point where it rocks, and there's a gap between them when rotated 180 degrees. The valve was seized closed, and I got it to move finally tapping the end with a block of oak and a hammer - it freed up some but still not as free as the exhaust which moves very easily. I sprayed some WD40 in the intake port and it wicks out the valve seat pretty quickly so I'm guessing I either need to buy a valve or at least lap it in again. What do you think? New pushrod and head gasket for sure, not sure about the valve. Are the torque specs and valve lash the same between this engine and the 407777 model? If so I'll use the ones in the I downloaded. The pictures in it looked identical to mine. The manual did leave some steps out for pulling the head, like removeing the exhaust manifold and a couple other items. Assuming I pull off the repair, I'll start using only regular gas with some 2 stroke oil in the future to make sure it's lubing the stems, looks like a common problem and I got lucky it didn't tear up the piston. thanks, Steve

This old thread lives on... I did a spring check on my lawn and garden power equipment last night. The old brute, now 32 years in youth, started up in a couple of pulls. It seemed to run great all the way to wide open. I did store my equipment over the winter with the valves closed per bill's storage tip. It did make a very loud squealing sound that came and went a few times. Kind of like a slipping belt sound. When it made the sound, it was constant for 3 to 5 seconds each time. Could this just be something as simple as the pull start housing rubbing on the fly wheel? Or is a bearing in the block starting to fail?

Is this something a novice should attempt, or should I call it quits and just eat a big 'ol repair bill? If there's guides to doing this I'm not adverse to trying, but I'm starting to feel like I'm in quicksand. I guess I should buy a project mower if I want to learn, not start on my main riding lawnmower, especially since I have ~1.5 acres to mow, and it really sucks mowing that all with a small pushmower. Is there a way to inspect to see if I bent the valves with a visual inspection, or is this going to require a history of technical knowledge and a micrometer?

Hopefully the engine failure analysis will come out in your favor. This is a definite science. Yet the rep has the ability to make their decision towards your side if you prove a good earnest case if the physical evidence says- yes, there is dirt ingestion, yes, the guys a filter isn't new- but was a BS part and should have been doing the job and so on. The reps mission is NOT to deny your claim. If dirt ingestion is due to the inability for the housing to seal, that would be good news with this engine. You wouldn't be the only one who has had that issue if that what it comes back as. I must say that blowing through a paper element is not acceptable as the pressure can tear the media and compromise the filter. Be sure to post how things come out. Bring records of any kind to support your claim of maintenance. Marks on the calender, scribbles on the back of the manual- it all backs your claims.