Wp76 Posted January 6 So... Rode three motos today (practice). Bike ran perfect the entire time. Zero signs of any issue. Went to ride a fourth moto and bike won't fire. Engine turns over like normal but does not even try to start. 2018 fc250. Stock engine and electronics. No blink codes. Fuel and air filter is fine. Tried a different ECU. No change. Nothing frayed or unplugged. Fuel pump sounds as if it's priming as normal. I recently had the sub frame off to remove the shock but no wiring was detached and everything seems fine. Any thoughts on tests to run? Share this post Link to post Share on other sites
mirnldi Posted January 6 Kill switch? This got me a few times as a new owner. Share this post Link to post Share on other sites
Doc Brown Posted January 6 Disconnect kill switch and try again. Check if you have a healthy spark. Share this post Link to post Share on other sites
Wp76 Posted January 7 15 hours ago, Doc Brown said: Disconnect kill switch and try again. Check if you have a healthy spark. Spark is strong. Injector functions. Sprays a good mist when cranking. Valves are in spec. Cams are in time. Fuel pump is sending fuel. Fuel pump relay is functioning. It's getting air, fuel and spark but it's not even trying to fire. Share this post Link to post Share on other sites
Wp76 Posted January 7 23 hours ago, mirnldi said: Kill switch? This got me a few times as a new owner. I unhooked it just in case. Nothin. Not to mention it is giving good spark also. Share this post Link to post Share on other sites
Wp76 Posted January 7 19 hours ago, 1 lunger said: Check fuses There's only a single fuse in the system... It's all good. Everything so far has checked out perfectly. Spark, fuel, air, mechanical timing. Tip over sensors. Still won't start. Share this post Link to post Share on other sites
Doc Brown Posted January 7 5 hours ago, Wp76 said: Spark is strong. Injector functions. Sprays a good mist when cranking. Valves are in spec. Cams are in time. Fuel pump is sending fuel. Fuel pump relay is functioning. It's getting air, fuel and spark but it's not even trying to fire. Mh...seems you have checked all the common things and even more. Very strange. Sorry no idea at the moment.... Share this post Link to post Share on other sites
Wp76 Posted January 8 18 hours ago, Doc Brown said: Mh...seems you have checked all the common things and even more. Very strange. Sorry no idea at the moment.... Next check is compression. I actually hope the top end failed. These electrical Gremlins are a drag. Share this post Link to post Share on other sites
Rembrand Posted January 8 Have you tried a new spark plug? A good spark in open air does not guarantee a good spark under compression. 1 Share this post Link to post Share on other sites
Doc Brown Posted January 8 3 hours ago, Rembrand said: Have you tried a new spark plug? A good spark in open air does not guarantee a good spark under compression. Good point that! Try this before disassembling the engine... Share this post Link to post Share on other sites
Wp76 Posted January 10 So... Update. No compression. Pulled the top end. Piston was cracked all the way through. A mechanical failure is super surprising since it had to have occurred as the bike cooled down after the Moto. I'm guessing the ring got jammed (lean) and broke when I tried to restart. Gonna get spendy! Any piston suggestions beyond OEM? On 1/7/2019 at 11:05 PM, Doc Brown said: Good point that! Try this before disassembling the engine... 1 Share this post Link to post Share on other sites
Doc Brown Posted January 10 5 hours ago, Wp76 said: So... Update. No compression. Pulled the top end. Piston was cracked all the way through. A mechanical failure is super surprising since it had to have occurred as the bike cooled down after the Moto. I'm guessing the ring got jammed (lean) and broke when I tried to restart. Gonna get spendy! Any piston suggestions beyond OEM? That's real bad. Hope you get it sorted soon. Share this post Link to post Share on other sites
Rembrand Posted January 10 15 hours ago, Wp76 said: So... Update. No compression. Pulled the top end. Piston was cracked all the way through. A mechanical failure is super surprising since it had to have occurred as the bike cooled down after the Moto. I'm guessing the ring got jammed (lean) and broke when I tried to restart. Gonna get spendy! Any piston suggestions beyond OEM? How many hours on that piston? I just put a Wiseco in my FC350. Share this post Link to post Share on other sites
Wp76 Posted January 10 5 hours ago, Rembrand said: How many hours on that piston? I just put a Wiseco in my FC350. 62 hours on the Piston. More than I typically would run but... The Piston looked in great condition as far as wear. The issue was heat from a lean map setting. The husky appears to be mapped with the stock air box configuration in mind. The combination of the drilled air box, sea level, cold temps and hard running created lean condition. Rings got tight. Got hot. Broke the Piston. I've got a new vertex and cylinder on the way. 1 Share this post Link to post Share on other sites
Rembrand Posted January 10 2 hours ago, Wp76 said: 62 hours on the Piston. More than I typically would run but... The Piston looked in great condition as far as wear. The issue was heat from a lean map setting. The husky appears to be mapped with the stock air box configuration in mind. The combination of the drilled air box, sea level, cold temps and hard running created lean condition. Rings got tight. Got hot. Broke the Piston. I've got a new vertex and cylinder on the way. I had 120 hrs on mine and still looked good but then how hard can I run it, over 60 vet. Share this post Link to post Share on other sites
