wr 450 no spark

4 replies to this topic
  • kwakebord

Posted September 25, 2005 - 07:03 PM


Hi Guys, I am new to WR land. Just bought a 2003 wr 450 with approx. 2 hrs of run time. it's true, the guy rode it at Pismo, and freaked at the squirrlyness of ridin sand and parked it. Thats where I came in, purchased for $3000.00 US dollars looks NEW NEW NEW Ah but it does'nt start.

Problem #1 looks like the starter clutch is not engaging, it simply spinns the starter, remove the cover, and the clutch assm. and the gear it engages to in side the housing spins both ways, more than likely the woodruff key is out. Any additional thoughts??

#2 No spark, The guy bought a new Yuasa, I have fully trickeled it outside the bike, fresh gas, drained the carb, He claims to have heard a back fire whilst kicking it, a day earlier. I currently have no spark. basicly I have laid the spark plug on the head bolt, and kicked like hell, no spark. I even tried to electicute myself, no jolt. pulled all connectors apart and checked tightness, did all the tests in the book, checked fuses, neutral switch, clutch switch main etc. all looks good. Got Clues??? Thanks Ken


Posted September 25, 2005 - 07:16 PM


More than likely the flywheel has spun on the crankshaft. Repair it and do the '04 starter upgrade. My bet is you will have spark. Also the ignition switch has to be on to get spark even when kick starting.

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  • Indy_WR450

Posted September 25, 2005 - 07:42 PM


I agree most likely sheared flywheel key. O4 upgrade instructions are on this web site:


  • kwakebord

Posted September 25, 2005 - 08:26 PM


Hey, just pulled the sidecase, missing keyway confirmed, looks like an easy fix, just have to find the key in the bottom case, looks like the nut came un fastened, no sighns of damage to either component. Unbelievable that this could happen to a new bike. I believe that the nut was loosened by the few minutes of riding, and his attemp to kick start, the backfire, did the final few threads to loosen it off. Silly Yamaha, what do they pay their engineers anyway??? Thanks Guys I appreciate it. :banghead: I plan on doing a complete disassembly and grease everything, then riding the hell out of it!!! I'll be in touch for some performance tips.. Thanks again Ken : :applause:


Posted September 26, 2005 - 05:16 AM


This is old news. The problem is not that the flywheel nut came loose. The '03's had a serious starter design flaw. Do a search on '03 starter problems. You'll find more than you ever wanted to know. Yamaha fixed it in '04 and luckily the '04 starter design is retrofittable. Go to the site Indy posted to see the '04 install. Simply replacing the key will not provide a permanent fix.


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