B&S 303777 wont run after new rings

[wywy]

Hello everyone first time here, I have an old snapper mower with a b&s 303777, I did the rings on it and I cannot get it to run right, a little recap first though, the cylinder that runs the fuel pump was down to about 10 psi, 2nd was around 30, so I disassembled and got new rings for it, also lapped the valves, then it seemed to be seized apparently so I left it in my garage for about 2 weeks because I went on vacation to my grandparents house, when I got back the engine rotated fine so I got a new starter and it ran but very poorly, after about an hour of running I saw that the exhaust pipe midway down was glowing red hot, so I shut it down and let it cool and then I was just busy for a very long time so I never did anything with it, I started it up again for some more diag about 3 weeks later and noticed that the choke seemed to be controlling the rpm, and also about 30 seconds of running was making the exhaust pipe smoke, it again sat for about 2 weeks, I came out a couple days ago and it does the same thing but now it is very difficult to even get running, when I turn it over it fires for about a second then I can see the governor slams the throttle plate closed and then the engine dies, I have made a few attempts and got it to run but still the rpm is controlled mostly by the choke, exhaust also smokes in about 10 or 15 seconds, I did take the govenor system off and throttle system off more times then I can count and tried putting springs in different locations but nothing really fit so it's all back together I'm what I remember is the correct way I'm more of just at a loss of what's causing this, carburetor was dirty but I cleaned it out and stuff but the carb was never an issue to begin with, I have ran it off starter fluid for a lil bit but I still needed the choke to be almost completely blocking air off for it to run, when it has run the more I block off air using the choke the faster it runs, I am 17 and I don't have a ton of knowledge on this kind of stuff but I'm kinda thinking I wrecked the governor or throttle system, would appreciate any ideas that anyone might have thank you

 

[Rivets]

Sounds like you may have gotten in a little over your head. Can this be solved, YES, but it is going to take patience and a little work on your part. You will have to start over and check everything you have done, to find the problem. Because you did not do things systematically you may now have multiple problems. Here is a service manual which should give you some help. Post back if you have specific questions. https://mudbuddy.com/wp-content/uploads/2024/02/vanguard-repair-manual.pdf

 

[wywy]

Thank you, where do you suggest I start? This was my first time doing a mower engine so i didnt really know what i was getting myself into when i did the rings and i should've put more care and detail into it, but at least the rings and vaves are sealing i have 125psi in both now, but I'm just stuck on what could potentially cause this condition but I would assume it's one of the 3, carb, governor or fuel?

 

[StarTech]

Well starting you probably made several mistakes.

First you can't simply throw in a set rings. The cylinder needs caliper used to determine each cylinder condition. IE how much wear, Is it worn oval, is it worn tapered. Also a good cylinder would need the glaze broken so the seat properly. But if the cylinder is worn pass .003 either oval or taper then a rigid hone needs to used and the cylinders honed to .020 over of course this means new pistons and rings. As using a flex hone only makes things worst. Rigid hone and stones are not cheap plus you need a 1/2" variable speed drill that can be slowed to under 300 rpm.

Second see if your high school has a trade [tech] center; there should be class on small repairs. Where you either sign up for classes or at least get some local help along with ours. Basically you need a good local mentor to help guide you through the learning process as there is a lot to learn at first and it can be overwhelming. But if you really want to learn the trade hands on is one of the best ways as you learn from your mistakes as well as your successes.

Above all read over the service manual Rivets linked first.

For now let's skip the governor. As first you need fuel, air, and the correct timing [both mechanically and electrically] along with good compression which you have already. The governor will to be set to keep the engine going into run away. But we got to get it to start up and idle.

 

[wywy]

Oh yes I forgot about that, I did measure the cylinder and out of round was I think .0008 with a dial bore gauge, taper and ridge were good to but I don't remember the measurements, I also did hone them using a 3 stone honer, crosshatch is good, I think I did a good job on the ring part but the governor and reassembly I messed up, I will go over that service manual today hopefully, am I correct to check the governor, fuel, and carb though?

 

[Rivets]

Before you touch the engine again you must get yourself a good understanding of all things which make an engine run. To do this I suggest that you find a couple of books on small engine repair at your local or school library. Check them out and start reading them and the repair manual I posted. As Star recommended look for an instructor or shop mechanic who will mentor you through this process. Realize that at this point it is going to take you a couple of weeks, maybe months, to get the engine running smooth again. I taught engine repair for 30+ years and the biggest problem you have now is this. “DO I HAVE THE PATIENCE TO SAY I SCREWED UP AND BE WILLING TO START OVER AT THE VERY BEGINNING.” This means reading everything I can so I understand what I am doing before I pick up another wrench. If you are willing to do that and get the engine running, I see someone who is a lot smarter than 90% of todays teenagers, and has a bright future.

 

[Craftsman Garage]

Before you touch the engine again you must get yourself a good understanding of all things which make an engine run. To do this I suggest that you find a couple of books on small engine repair at your local or school library. Check them out and start reading them and the repair manual I posted. As Star recommended look for an instructor or shop mechanic who will mentor you through this process. Realize that at this point it is going to take you a couple of weeks, maybe months, to get the engine running smooth again. I taught engine repair for 30+ years and the biggest problem you have now is this. “DO I HAVE THE PATIENCE TO SAY I SCREWED UP AND BE WILLING TO START OVER AT THE VERY BEGINNING.” This means reading everything I can so I understand what I am doing before I pick up another wrench. If you are willing to do that and get the engine running, I see someone who is a lot smarter than 90% of todays teenagers, and has a bright future.

I'm proud of being in that minority . As someone who was self taught, working on engines can be stressful at times and it's a lot when you first start, but as you get the hang of it, it starts to come to you naturally over time. Good luck @wywy, it looks like you're on the right track.

 

[Craftsman Garage]

Before you touch the engine again you must get yourself a good understanding of all things which make an engine run. To do this I suggest that you find a couple of books on small engine repair at your local or school library. Check them out and start reading them and the repair manual I posted. As Star recommended look for an instructor or shop mechanic who will mentor you through this process. Realize that at this point it is going to take you a couple of weeks, maybe months, to get the engine running smooth again. I taught engine repair for 30+ years and the biggest problem you have now is this. “DO I HAVE THE PATIENCE TO SAY I SCREWED UP AND BE WILLING TO START OVER AT THE VERY BEGINNING.” This means reading everything I can so I understand what I am doing before I pick up another wrench. If you are willing to do that and get the engine running, I see someone who is a lot smarter than 90% of todays teenagers, and has a bright future.

Also, most of today's teens don't set the bar very high. Just saying...

 

[StarTech]

As I once told my idiot brother that said questions I asked were stupid. At I least admit I don't know everything and asking questions is how I find out what I need to know. I told him if I knew I wouldn't be asking. Don't be afraid to ask for help even if the question seems dumb, if you don't truly know that the only way you are going an answer; hopefully the correct answer. A lot of us old guys are willing to try to help a new mechanic out.

Guess who he came to when he needed an answer to a problem or at least get pointed in the right direction.

 

[wywy]

Thanks for the support everyone I really appreciate it, I am decently educated in engines but I don't exactly think i am better then most teenagers but i hope to get to that point someday i am still just a kid really idk, I do think i am more educated in bigger engines but not really small ones but they are pretty similar, I go to traviss uni for automotive maintenance and light repair, it was the only thing that I could get in because everything else was full but I only joined earlier this year but so far I am self taught, I just don't have enough experience actually working though so I mess up simple things, I am getting my ase entry level by June I think, but my class only teaches and certifies 4 subjects, but I am a little bit ahead so my teacher had to get permission to give me more ase tests that arent technically supposed to be taught in my class, I haven't really asked my teacher about the mower yet because it's more of a car shop/classroom and he has said if I bring my mower in then everyone else will too, I am no professional but I know a good little bit about engines, I will read that manual tonight and see if I can see if it can give me some more info but I am just at a loss of what I could have done to cause this, it's kind of a so close yet so far situation, bigger engines are from my limited experience apparently easier to work on then these lol, again thanks for all the advice I will read that tonight and see what I can find, am I able to post a video on this I just thought It might help if I did, wow this was a little more of a rant then actual information sorry