Luger234 1 #1 Posted August 4, 2022 I bought a '97 520H that was a project at auction planning on keeping it for spare parts for my old 312 (tires, seat, frame, text etc.) but the more I looked at I found most of the parts there. In trying to get it running I was missing the P shaped keyway that holds the flywheel and turn the ignition ring, so I fashioned my own one or if keyway stock and a woodruff key. That was my first issue did a valve adjustment to get it to run as it wouldn't start and was backfiring. Got the right key and it ran ok for a bit but wouldn't restart as I ended up shearing the key. I TIG welded the key back together straight put it back in and I can get the mower to start after a bit but if I have the throttle and choke set right. I also did have the top off the carb cleaned the passages and sprayed air thru the idle and main circuits making sure they were clear. Right now when it starts it will run for about 30 seconds then die this is with the choke at about half and abbot half throttle. When it does run it does not rev up at all its running probably just above idle and is labored the vacuum gauge is at 75-100%. Also I have gas spitting out of the top of the carb and i have a heavy amount of gas coming out of the main circuit on the carb. Right now valves are set at a tight 5 and 13 thousands and i am out of ideas of what else to check to get this mower to run right. Any help would be appreciated. 1 Share this post Link to post Share on other sites
Cee245 826 #2 Posted August 4, 2022 Welcome to Red Square 🟥! As long as all major moving parts are in good shape, it sounds like fuel/carb related. These carbs are a bit finicky, first off. You should have a version of the Nikki 6100 carburetor. I have had to take it completely off to get mine to run right. Not just taking the top off. Many times it requires taking the carb completely apart and giving it a really good cleansing... ethanol laced gas gums things up in our small engines... Have you worked on these before? Do you have a leaky intake? Does it "surge" when runs? You'd have to take the intake off to get at the two bolts to take the carb off. Unless you make a special tool for it... 1 Share this post Link to post Share on other sites
953 nut 59,889 #3 Posted August 4, 2022 Sounds like a complete carburetor deep cleaning and rebuild is needed. 1 Share this post Link to post Share on other sites
lynnmor 7,813 #4 Posted August 4, 2022 Apparently you did have the intake manifold off to adjust the valves. Did you inspect the manifold for leaks? Did you use new Onan brand gaskets? There is a welch plug just above the idle mixture screw, did you remove both the welch plug and idle mixture screw to clean in those passages? You will need a new 3/8" aluminum welch plug if you decide to remove it. You might have an accelerator pump on your carburetor, if so you may have damaged it when using compressed air. Did you properly clean the taper on the crankshaft and inside the flywheel? Did you torque the flywheel bolt to 55 lb. ft.? Share this post Link to post Share on other sites
