tomtunas Posted April 5, 2007 Report Share Posted April 5, 2007 All you guys with cubs, I was riding this past weekend and all of a sudden my motor lost the "ping" in the pipe almost like a bog, "very rich". When I feather the throttle it picks back up on the pipe, but I dont know whats up with it. I was thinking mabye loose jet, broken reed? I checked plugs and they looked good. Its a 421 4 mill cub with 35's, and shearer inframes. It was running fine all day then all this shit happened. Quote Link to comment Share on other sites More sharing options...
r/atvshee Posted April 5, 2007 Report Share Posted April 5, 2007 it is very possible that there could be a broken reed. Also your pilot jet might've gotten clogged. Quote Link to comment Share on other sites More sharing options...
tomtunas Posted April 5, 2007 Author Report Share Posted April 5, 2007 I hope its something simple. I think I felt a slight case of detonation also I'm running pump gas with 20cc domes and timing advanced +4. It figures it happened when 5 450's showed up at the pit. I'm running v force reeds, are they common for breaking? Quote Link to comment Share on other sites More sharing options...
locogato11283 Posted April 5, 2007 Report Share Posted April 5, 2007 uhhh, 20cc domes and +4 timing on pump gas?? whats your compression? sound like you might have solved your own problem. what jetting? Quote Link to comment Share on other sites More sharing options...
cam2 Posted April 5, 2007 Report Share Posted April 5, 2007 uhhh, 20cc domes and +4 timing on pump gas?? whats your compression? sound like you might have solved your own problem. what jetting? wow, i agree. 20cc domes and +4 timing on pump gas is not a good mix. unless your elevation is real high, real high. i've seen and heard of v-forceII reeds breaking. how long have you ran this engine? like loco asked, check your compression, hopefully it's not too late. you may have to bump up the octane to around 100 unless your comp is high then you'll need more. Quote Link to comment Share on other sites More sharing options...
theshee Posted April 5, 2007 Report Share Posted April 5, 2007 I run 93 octane on 20s, but I am at over 5000 feet elevation. Quote Link to comment Share on other sites More sharing options...
bigboybanshee Posted April 5, 2007 Report Share Posted April 5, 2007 Might not be a bad idea to check your flywheel, make sure you didn't shear the woodruff key Quote Link to comment Share on other sites More sharing options...
tomtunas Posted April 6, 2007 Author Report Share Posted April 6, 2007 I believe the jets are 155 mains. Would VP C12 be ok? I'm gonna take the carbs and reeds off tomorrow and check compression. Ive ran the reeds for about 3 yrs. The bike ran fine all day, when it started acting up I just rode it to get back to the truck, so I hope theres no damage. Also noticed coolant dripping on my headpipes, I have a ESR temp gauge and the temp didnt get over 150. Running engine ice. Quote Link to comment Share on other sites More sharing options...
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