No Spark After Complete Rebuild 2005 YZ250F

BigNox

Member
Apr 28, 2022
1
0
Hey everyone, some help would be greatly appreciated I'm stumped and just want to go ride. My brother bought this bike around a year ago and we rode it for a an hour or two then kaboom the engine blew. Hole straight threw the bottom, I decided to take the project on myself and disassembled the engine, finding that the cylinder, piston ,and crankshaft were all ruined. I ordered all the required parts/bolts/gaskets and put the engine back together. Upon being assembled the engine would not start and felt like it had no compression, as well as no Spark. After this I brought the bike to my local shop who eventually after 3 weeks quoted me $1500 to rebuild head and fix the spark problem, they also said they couldn't figure out why there was no spark, they said the only thing they did was put a new spark plug and swap a black box from another 250 and still they got no spark. I wasn't about to pay that kind of money for something that seems so simple. Got the bike home and took the head off and brought it to my local machine shop who will be rebuilding it with kibblewhite valves and seals. I still have the Spark problem though and am seeking help on the problem, My question is what could I have damaged or put together wrong in the bottom end to cause this no spark Issue? I was wondering if maybe it has something to do with the weighted shaft or whatever it is called pictured in the image below. or maybe that one of the copper coils is exposed. Any help would be greatly appreciated. I have included multiple pictures.

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