xArmstrongx
XS400 Member
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Hi there!
My name is Nate and I recently bought a 1981 xs 400 and I'm having some trouble getting the jetting right.
It has Uni Pod filters and straight pipes. It's been running pretty poorly as of late and after researching the topic for awhile I decided it was time to try and fix the problem.. I recently cleaned the carbs and upped the main jet to a 145 and the pilot jet to a 45 (BS30/96 type). If i'm correct that should be one size up on both the main and pilot from stock. I also moved the air screw out to 3.5 turns, then to 4. I don't have a synch tool so I just adjusted the butterflies until they were really close. I've heard of making your own home made sych tool, if anyone has some info how to do this that'd be greatly appreciated. hmm Travis *cough *cough... haha It idles at about 1200 like the manual says.
Needless to say the bike is running like ass lol At about quarter throttle it gargles and cuts out pretty bad. From about half to full is better, but you can't crack it wide open or else it'll start cutting out all the way until the top. It sometimes pops on deacceleration. I cleaned the plugs and put them back in, hoping I'd be able to read them and figure out if I'm too lean or rich. If I'm sitting on the bike, the plug out of the left cylinder is mostly tan in the middle and black around the edge. Which I figured isn't too bad, cause tan is what you want. The right plug however is pitch black. It's not a wet black though (oil), which is good. How could that be if both carbs are jetted and adjusted the same exact way? Maybe the left cylinder isn't firing as well as teh right? Also, sometimes when i come to a stop and let the bike idle it'll die. It fires back up, but obviously it shouldn't be doing that.
The intake manifolds do have some cracks in them, but I don't think they go all the way through.
Also, where I ride at is about 574 feet in elevation.
Any advice, pointers, etc would be greatly appreciated.
Thanks in advance and RIDE ON!
My name is Nate and I recently bought a 1981 xs 400 and I'm having some trouble getting the jetting right.
It has Uni Pod filters and straight pipes. It's been running pretty poorly as of late and after researching the topic for awhile I decided it was time to try and fix the problem.. I recently cleaned the carbs and upped the main jet to a 145 and the pilot jet to a 45 (BS30/96 type). If i'm correct that should be one size up on both the main and pilot from stock. I also moved the air screw out to 3.5 turns, then to 4. I don't have a synch tool so I just adjusted the butterflies until they were really close. I've heard of making your own home made sych tool, if anyone has some info how to do this that'd be greatly appreciated. hmm Travis *cough *cough... haha It idles at about 1200 like the manual says.
Needless to say the bike is running like ass lol At about quarter throttle it gargles and cuts out pretty bad. From about half to full is better, but you can't crack it wide open or else it'll start cutting out all the way until the top. It sometimes pops on deacceleration. I cleaned the plugs and put them back in, hoping I'd be able to read them and figure out if I'm too lean or rich. If I'm sitting on the bike, the plug out of the left cylinder is mostly tan in the middle and black around the edge. Which I figured isn't too bad, cause tan is what you want. The right plug however is pitch black. It's not a wet black though (oil), which is good. How could that be if both carbs are jetted and adjusted the same exact way? Maybe the left cylinder isn't firing as well as teh right? Also, sometimes when i come to a stop and let the bike idle it'll die. It fires back up, but obviously it shouldn't be doing that.
The intake manifolds do have some cracks in them, but I don't think they go all the way through.
Also, where I ride at is about 574 feet in elevation.
Any advice, pointers, etc would be greatly appreciated.
Thanks in advance and RIDE ON!
