jinxlovesmax
XS400 Member
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- 14
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hey guys, i have a 1978 xs400. been trying to get her to start for the past couple days with no success. first off i want to say THANKYOU to everyone that contributes to this site. it is such an amazing resource and i have learned so much from reading these forums as i have been since i got my bike last summer.
last summer i bought this bike non running. but this was not a bike that has been sitting for long, it was pretty damn clean and has minimal rust. 23,000 miles on it. fixed a stripped spark plug hole and got it to run very poorly (on 1 cylinder, had to have throttle open, backfiring) but at least running. i thought this was due to the carbs, which were atrocious. so i figured i'd put on a "new" set of carbs and it will be ok. but if i adjust the timing and valves with new carbs, it will be great! well no. i did that. and now its not working AT ALL.
i set the timing with a timing light (used tutorial from that youtube video) and timing is spot on. i also set the points gap and spark plug gap. (used specs from manual). points are in good shape.
i adjusted valves. intake to .004 and exhaust to .007, did that by aligning the LT/RT marks after i felt compression on my thumb over spark plug hole.checked for both rockers loose, and also used screwdriver to make sure piston was at the top when i did it.
cleaned carbs. completely disassembled, except for butterfly valves. soaked in simple green and cleaned in a heated ultrasonic cleaner. blew them out with compressed air. bench synched and set pilot mix screws to 3.5 turns out. set foats to 26mm from float bowl mating surface (or whatever its called). i was very thorough in making sure all jets were completely clean.
im getting spark at both spark plugs. tested by taking out plug and grounding it to engine.
Fresh gas, no rust in tank, rebuilt petcock, inline fuel filter.
Fully charged the battery and had it hooked up to the charger when i tired to start it.
I've been using the electric start mostly when i try to start it. not more than 5 seconds at a time. i have the wheels off the bike at the moment and i don't want to tip over when im trying to kick it!
the only thing i get when im trying to start it is the occasional backfire. had a poof of smoke come from the left side carb area once. no sound of "wanting" to start.
i don't know what to do except maybe trying to clean the carbs again. what do you guys think? Am i forgetting something?? ANY help is greatly appreciated!
last summer i bought this bike non running. but this was not a bike that has been sitting for long, it was pretty damn clean and has minimal rust. 23,000 miles on it. fixed a stripped spark plug hole and got it to run very poorly (on 1 cylinder, had to have throttle open, backfiring) but at least running. i thought this was due to the carbs, which were atrocious. so i figured i'd put on a "new" set of carbs and it will be ok. but if i adjust the timing and valves with new carbs, it will be great! well no. i did that. and now its not working AT ALL.
i set the timing with a timing light (used tutorial from that youtube video) and timing is spot on. i also set the points gap and spark plug gap. (used specs from manual). points are in good shape.
i adjusted valves. intake to .004 and exhaust to .007, did that by aligning the LT/RT marks after i felt compression on my thumb over spark plug hole.checked for both rockers loose, and also used screwdriver to make sure piston was at the top when i did it.
cleaned carbs. completely disassembled, except for butterfly valves. soaked in simple green and cleaned in a heated ultrasonic cleaner. blew them out with compressed air. bench synched and set pilot mix screws to 3.5 turns out. set foats to 26mm from float bowl mating surface (or whatever its called). i was very thorough in making sure all jets were completely clean.
im getting spark at both spark plugs. tested by taking out plug and grounding it to engine.
Fresh gas, no rust in tank, rebuilt petcock, inline fuel filter.
Fully charged the battery and had it hooked up to the charger when i tired to start it.
I've been using the electric start mostly when i try to start it. not more than 5 seconds at a time. i have the wheels off the bike at the moment and i don't want to tip over when im trying to kick it!
the only thing i get when im trying to start it is the occasional backfire. had a poof of smoke come from the left side carb area once. no sound of "wanting" to start.
i don't know what to do except maybe trying to clean the carbs again. what do you guys think? Am i forgetting something?? ANY help is greatly appreciated!