Brian Scott
Husqvarna
AA Class
Here's my long winded story. What's your diagnosis please?
2 rides ago: About two hours into my ride the head pipe smacked a rock riding through some densely wooded single track, which put a 1" dia. x 0.5" deep cone shaped dent in it about 12" downstream of the cylinder. Shortly thereafter my bike started cutting out and stalling making the infamous "boowah" sound. I was able to limp it back to my truck, but it was cutting out and stalling intermittently in most speeds/gears and throttle openings. A plug swap didn't help and it was clean like it wasn't sparking much or very hot. The bike ran perfectly prior to this during short local rides and during 4 -5 hr long enduros w/out issue, so I'm sure jetting was not the cause. Did smacking the rock w/the pipe cause this, or was it just coincidental timing that something else reared its ugly head? Back home I discovered the inside of the carb/reed block manifold was severely cracked and had a small hole in the top where the clamp screw is located. Swapped it for a new one. Also checked the reeds, air cleaner and serviced the carb to ensure float level was good and jets and air/fuel circuits were clean (Keihin PWK AS, 42 PJ, AS 1.5, red JD needle 3rd clip, 175 main, 50:1). Installed 2 new gaskets on the reed cage. Verified power valve operation, tank venting, no fuel blockage, and repacked the oem silencer (use heat and chisel off the rivets). Verified coolant was circulating and that coolant was not entering the cylinder. I run the oem dash, but have the headlight disconnected. Recently installed a Rekluse Z-Start Pro. Bike started w/out issue at home and ran great while putting around the front yard and street for 20 minutes or so. No real load applied to engine during this short trial. Problem solved? Bike has about 170 hrs and is about 50 hrs into it's second top end. Also have the high comp head on it. Compression seems fine, but I haven't tested it to verify.
1 ride ago: The bike ran fine after letting it warm up sufficiently in the parking lot and for the first few miles (same place and weather conditions as before). After 20 to 30 minutes and several decent technical climbs that loaded the engine it started behaving the same way again: boowah, then dead. This time it was worse. Couldn't keep it going for 1/4 mile w/out it cutting out (like their is a spark or fuel delivery or jetting issue) and eventually stalling. Finally was unable to start it after a few miles of this. Took a break to pull off the carb to double check the plug. Carb was fine, plug was swapped for a new one and was too clean and looking like it was not working. Bike fired up after 15-20 minutes of trail side work, but took many kicks. Within a few minutes of riding, same thing would happen. Limped it back to the truck again barely for diagnosis. Fiddled w/the AS for awhile. Bike got really hot doing this and started knocking, so turned in the AS to keep it rich. When I could keep it idling it would die as soon as I put it in gear w/the clutch pulled in. Took it home for more diagnosis. Thinking it's electrical now...
Checked plug cap/wire resistance at 7k ohms. Wire was 2k ohms, so cap must be 5k ohm like it says on the boot. Checked voltage of lead into the voltage regulator (brown wire from stator) at 12v with engine running. While turning the flywheel using a power drill with the plug out the plug is sparking blue sparks when ground to the engine block, I'm getting about 16 volts at the brown wire and about 8 volts at the red wire that enters the coil/cdi (the drill is only able to turn the flywheel less than idle speed hence the low voltage readings I suspect). Not sure how to test for 35-36 volts w/the voltage regulator disconnected like the workshop manual states. All grounds to frame were clean and tight. Didn't find any chafed wires either. Haven't pulled the flywheel off yet to check the stator; waiting for a flywheel puller to arrive. Will be difficult to mimic same conditions that cause the issue at home. Hmmm.
So what's causing my bike to cut out and stall after it's warmed up?
2 rides ago: About two hours into my ride the head pipe smacked a rock riding through some densely wooded single track, which put a 1" dia. x 0.5" deep cone shaped dent in it about 12" downstream of the cylinder. Shortly thereafter my bike started cutting out and stalling making the infamous "boowah" sound. I was able to limp it back to my truck, but it was cutting out and stalling intermittently in most speeds/gears and throttle openings. A plug swap didn't help and it was clean like it wasn't sparking much or very hot. The bike ran perfectly prior to this during short local rides and during 4 -5 hr long enduros w/out issue, so I'm sure jetting was not the cause. Did smacking the rock w/the pipe cause this, or was it just coincidental timing that something else reared its ugly head? Back home I discovered the inside of the carb/reed block manifold was severely cracked and had a small hole in the top where the clamp screw is located. Swapped it for a new one. Also checked the reeds, air cleaner and serviced the carb to ensure float level was good and jets and air/fuel circuits were clean (Keihin PWK AS, 42 PJ, AS 1.5, red JD needle 3rd clip, 175 main, 50:1). Installed 2 new gaskets on the reed cage. Verified power valve operation, tank venting, no fuel blockage, and repacked the oem silencer (use heat and chisel off the rivets). Verified coolant was circulating and that coolant was not entering the cylinder. I run the oem dash, but have the headlight disconnected. Recently installed a Rekluse Z-Start Pro. Bike started w/out issue at home and ran great while putting around the front yard and street for 20 minutes or so. No real load applied to engine during this short trial. Problem solved? Bike has about 170 hrs and is about 50 hrs into it's second top end. Also have the high comp head on it. Compression seems fine, but I haven't tested it to verify.
1 ride ago: The bike ran fine after letting it warm up sufficiently in the parking lot and for the first few miles (same place and weather conditions as before). After 20 to 30 minutes and several decent technical climbs that loaded the engine it started behaving the same way again: boowah, then dead. This time it was worse. Couldn't keep it going for 1/4 mile w/out it cutting out (like their is a spark or fuel delivery or jetting issue) and eventually stalling. Finally was unable to start it after a few miles of this. Took a break to pull off the carb to double check the plug. Carb was fine, plug was swapped for a new one and was too clean and looking like it was not working. Bike fired up after 15-20 minutes of trail side work, but took many kicks. Within a few minutes of riding, same thing would happen. Limped it back to the truck again barely for diagnosis. Fiddled w/the AS for awhile. Bike got really hot doing this and started knocking, so turned in the AS to keep it rich. When I could keep it idling it would die as soon as I put it in gear w/the clutch pulled in. Took it home for more diagnosis. Thinking it's electrical now...
Checked plug cap/wire resistance at 7k ohms. Wire was 2k ohms, so cap must be 5k ohm like it says on the boot. Checked voltage of lead into the voltage regulator (brown wire from stator) at 12v with engine running. While turning the flywheel using a power drill with the plug out the plug is sparking blue sparks when ground to the engine block, I'm getting about 16 volts at the brown wire and about 8 volts at the red wire that enters the coil/cdi (the drill is only able to turn the flywheel less than idle speed hence the low voltage readings I suspect). Not sure how to test for 35-36 volts w/the voltage regulator disconnected like the workshop manual states. All grounds to frame were clean and tight. Didn't find any chafed wires either. Haven't pulled the flywheel off yet to check the stator; waiting for a flywheel puller to arrive. Will be difficult to mimic same conditions that cause the issue at home. Hmmm.
So what's causing my bike to cut out and stall after it's warmed up?