lowkhalbalr Posted July 4, 2019 Report Share Posted July 4, 2019 Im breathing life back into a 2004....... According to the prevoius owner... Its a 421 athena build @ 68.4mm bore. I have no idea what domes he had installed. but, my question is **what should the compression range be at sea level?** Currently, im at 125PSI in both cylinders. I have run the engine in the past and it always started and ran on the 1st or 2nd kick idling beautifully. As of about a week ago, Im unable to get it runnning at all. It seems to not have ignition (as in it doesnt even try to start). however, my plug tester shows a great spark. my harness, stator, pickup, primary and secondary coils check well within ohmic limits but i cant get it to light off. Additionally, the tors has been removed. I have ohmed out and bypassed the kill switch and key switch for sanity reasons and I still have spark. Im not sure where to go from there. Ive also tryed the old carb cleaner in the carb trick....no luck... Ive tryed 2 different cdi's and ignition coils just because I had the parts on hand (the parts came off of running bikes). The Vforce 3 reeds are in great shape and the first thing I did was replace the plugs (gap set to .030) The bike has a new, unadulterated wiring harness that I personally installed. I then rode the bike without problems post harness installation. Im an A&P mechanic by trade and this damn thing is melting my brain... help a brother out pls Quote Link to comment Share on other sites More sharing options...
Keno Posted July 4, 2019 Report Share Posted July 4, 2019 Check the flywheel. It may have spun for some reason causing the timing to be way off. There is a woodruff key for alignment on the taper. Quote Link to comment Share on other sites More sharing options...
Ayesully810 Posted July 5, 2019 Report Share Posted July 5, 2019 (edited) if your getting some spark then dump fuel in the cylinders see if it fires if it does its a carb issue. 125 is usually stock compression around that I doubt that its an athena with 24 cc domes so its probably tired but it should still fire at that psi id imagine. Edited July 5, 2019 by Ayesully810 Quote Link to comment Share on other sites More sharing options...
lowkhalbalr Posted July 5, 2019 Author Report Share Posted July 5, 2019 12 hours ago, Ayesully810 said: if your getting some spark then dump fuel in the cylinders see if it fires if it does its a carb issue. 125 is usually stock compression around that I doubt that its an athena with 24 cc domes so its probably tired but it should still fire at that psi id imagine. Thats my thinnking as well. I knew when I bought the bike that id have to over haul it. But, before I do that I want to be 100% that im not over looking something stupid. Quote Link to comment Share on other sites More sharing options...
lowkhalbalr Posted July 5, 2019 Author Report Share Posted July 5, 2019 15 hours ago, Keno said: Check the flywheel. It may have spun for some reason causing the timing to be way off. There is a woodruff key for alignment on the taper. Woodruff is set in place correctly. thanks though Quote Link to comment Share on other sites More sharing options...
Ayesully810 Posted July 8, 2019 Report Share Posted July 8, 2019 (edited) you get that kitty to purr yet? Edited July 8, 2019 by Ayesully810 Quote Link to comment Share on other sites More sharing options...
lowkhalbalr Posted August 5, 2019 Author Report Share Posted August 5, 2019 (edited) On 7/8/2019 at 5:01 PM, Ayesully810 said: you get that kitty to purr yet? yes. today actually. After dwelling on the data I had collected previously; (see initial post.) I replaced the ignition coil to no avail. From there I replaced the stator assembly, then mounted a new OEM Yamaha stator on a billet adjustable plate (set to +1*) and it started right up. note taken. Just because a stator falls within textbook limits does not mean its functioning correctly. My guess is an internal short in one of the stator windings, producing a very off time scenario. Edited August 5, 2019 by lowkhalbalr Quote Link to comment Share on other sites More sharing options...
Ayesully810 Posted August 6, 2019 Report Share Posted August 6, 2019 good to know, was it an oem stator on there to begin with? Quote Link to comment Share on other sites More sharing options...
lowkhalbalr Posted August 27, 2019 Author Report Share Posted August 27, 2019 On 8/6/2019 at 3:12 PM, Ayesully810 said: good to know, was it an oem stator on there to begin with? yes it was and I replaced it with an OEM stator. I ran the bike for a few hours two weeks ago with no issues at all; now, I cant get it to start. Its exhibiting the same issue as before. The new stator ohms out within tolerance as well as the pickup. Have you heard of a flywheel with a cracked magnet that still produces a nice blue spark? Im grasping at straws here... 1 Quote Link to comment Share on other sites More sharing options...
Ayesully810 Posted August 27, 2019 Report Share Posted August 27, 2019 (edited) weird. as far as the flywheel no, usually it wont cause a no spark situation, it will usually just break up at higher rpms. maybe once over your wire harness, is it an oem harness as well? where did you order it from? id pull the plugs too and take a look at em see what they look like just to make sure Edited August 27, 2019 by Ayesully810 Quote Link to comment Share on other sites More sharing options...
the boris Posted August 28, 2019 Report Share Posted August 28, 2019 yes it was and I replaced it with an OEM stator. I ran the bike for a few hours two weeks ago with no issues at all; now, I cant get it to start. Its exhibiting the same issue as before. The new stator ohms out within tolerance as well as the pickup. Have you heard of a flywheel with a cracked magnet that still produces a nice blue spark? Im grasping at straws here...So both spark plugs have a nice spark but the bike wont start?I had a problem with resistors inside of the spark plug boots, I had a spark on one but not on the other, and the one i had was weak. Sent from my ONEPLUS A3000 using Tapatalk Quote Link to comment Share on other sites More sharing options...
lowkhalbalr Posted August 28, 2019 Author Report Share Posted August 28, 2019 18 hours ago, Ayesully810 said: weird. as far as the flywheel no, usually it wont cause a no spark situation, it will usually just break up at higher rpms. maybe once over your wire harness, is it an oem harness as well? where did you order it from? id pull the plugs too and take a look at em see what they look like just to make sure gotcha, jw. Yeah, its and OEM harness and stator / flywheel. I started the bike the night before I left town for a week and it started right up.....this is frustrating. Im thinking that this part failure is coincidental. If I had a stator failure, would it be possible to still have spark at the plug? but a no-ignition scenario? Quote Link to comment Share on other sites More sharing options...
lowkhalbalr Posted August 28, 2019 Author Report Share Posted August 28, 2019 17 hours ago, the boris said: So both spark plugs have a nice spark but the bike wont start? I had a problem with resistors inside of the spark plug boots, I had a spark on one but not on the other, and the one i had was weak. Sent from my ONEPLUS A3000 using Tapatalk I installed a new coil, leads and boots. I have a nice blue spark to the plugs when I ground them to a headbolt. 1 Quote Link to comment Share on other sites More sharing options...
lowkhalbalr Posted August 28, 2019 Author Report Share Posted August 28, 2019 18 hours ago, Ayesully810 said: weird. as far as the flywheel no, usually it wont cause a no spark situation, it will usually just break up at higher rpms. maybe once over your wire harness, is it an oem harness as well? where did you order it from? id pull the plugs too and take a look at em see what they look like just to make sure How does one go about checking ground? Quote Link to comment Share on other sites More sharing options...
gusto Posted August 28, 2019 Report Share Posted August 28, 2019 I just refile the metal on the frame and re-install. Throw on your old harness and see if that is the cause. If the old harness when installed still doesn't fire up I would start looking at the carbs. Have you checked the compression after the non start issues? Quote Link to comment Share on other sites More sharing options...
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