jeepman128 Posted February 3, 2007 Author Report Posted February 3, 2007 (edited) Well, its been a hectic week, so I haven't had a chance to tear into it yet to check the squish, but am planning on it on Sunday when I get back in town. I honestly can't remember what the pilot jet size is off the top of my head, but the needle is on the second up from the bottom and the main is a 160, the idle air screws were about 1 and half turns out.. but I was talking to Jefro over at FAST and he was wondering something to... I have had an issue the past 4 or 5 trips with atleast one spark plug working itself out of the head..and coming completely out... it happens atleast once a dune trip... I am definately going to check the squish, but the guy that helped me build said it was at .40... but who knows I'll double check and let ya know.. any ideas on what you think the spark plug issue might be? Edited February 3, 2007 by jeepman128 Quote
wesw Posted February 3, 2007 Report Posted February 3, 2007 what gas you running?? how old is it?? you should find out what your pilot and needle is also. Quote
jeepman128 Posted February 4, 2007 Author Report Posted February 4, 2007 what gas you running?? how old is it?? you should find out what your pilot and needle is also. Well, I still haven't had a chance to tear into the carbs but I did check the squish and both cylnders are at .039... so that can't be the problem... I will check the pilot this week and let ya know... but being the fact it has done it with all 3 carb set-ups on it, I am thinking its a lack of compression, but I will check and let ya know the gas was brand new pump gas 91 octane Quote
No Limit Powersports Posted February 5, 2007 Report Posted February 5, 2007 Is this motor ported what base gasket does it have??? Your motor will thank you if you gave it some more timing and compression, but make sure you order a dome with the right step in it so you dont mess up your squish. If you have good compression, the squish is correct and the motor is not ported i would start with jetting...if you have ever backed out a plug your lean, are you running a pingel?? Also something else to check is ignition maybe the bike has a weak ignition, coil, plugs, wires. Trust me a 421 cub should be making way more than 75hp all the 421's ive built will start in 3rd or 4th it dont really matter it should pull it. Quote
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