BScheer 3 #1 Posted July 20 I have a 520 LXI wheel horse that is missing and backfiring on high speed. It runs fine on low speed and does not backfire. The carb has been gone through completely and a new coil on right bank. The right bank is the one that is missing firing at high speed. Both cylinders have 150 lbs of compression. Does anyone have any ideas of what might be wrong? Thanks in advance for any help you might have to offer. Share this post Link to post Share on other sites
lynnmor 7,817 #2 Posted July 20 Start with new spark plugs and check the wires. 1 Share this post Link to post Share on other sites
953 nut 60,013 #3 Posted July 21 If an engine idles well, but runs erratically when revved up, like it hits and misses, pops and backfires, then chances are, it needs a new condenser/capacitor. And always install a condenser/capacitor with the wire facing downward so rain water and/or when washing off engine, water will not enter inside condenser/capacitor, ruining it. With water inside the condenser, this will also allow it to idle well, but cause it to run erratically when revved up Share this post Link to post Share on other sites
