WelderDave
XS400 Addict
So there’s not a lot of info about these carbs on here, most of it is in the 650 forum, so I’m gonna write some stuff up in mine. Bear with me, I’m learning as I go with carbs, got everything down pretty well though.
First off, it’s a good kit, I recommend a non vacuum petcock with a 90’ elbow and a T splitter all available on their site as well and don’t come in the kit.
Tuning is a bit different. Here goes.
Bought the 650 kit by mistake, but they are exactly the same except the jets.
650 comes with:
35 pilot, 120 main
400 comes with:
30 pilot, 105 main
Main issue experienced with 650 and the 400 is the jets coinciding with the kit. Had to jump up a pilot and main jet size for myself as well as others with 650’s so the jets are a tad lean out of the box (also depends on your engine and altitude). I’ve got 35 pilot and 110 main (however I suspect I need a 115, but I won’t know until I get a chance to really ride it)
All my maintenance is up to snuff, points, valve clearance, etc. just to note.
All that is good and easy to figure out, do your pilot jet and main jets first because this is where it gets hairy. These kits come with the same needle profiles! Not good. You can get your jets right and drive it fine and all, but the midrange off-idle is rich and bogs the engine and can kill it if you snap the throttle. The profiles are off with both kits. ( I’ve compensated a bit for this by raising the clip and increased idle so it’s not so bad, but it only covers up the initial problem). I did some more digging, and found someone who diagnosed this issue and landed on jjm needle to really get it.
Currently, I don’t have time at the moment to check the needle profile to let you know what comes with the carbs, but I will be doing so at some point very soon. I want a starting point before buying needles, and I’m trying to get into contact with the guy from the 650 forum that has it figured out so I can see how things pan out. I’m assuming profiles will be similar as the jetting isn’t to far off.
I’ll keep everyone posted as I make progress, I figure it will come in handy when someone else is looking or is just “dealing” with how they are like I have been until I got fed up. I want throttle response and smooth performance.
First off, it’s a good kit, I recommend a non vacuum petcock with a 90’ elbow and a T splitter all available on their site as well and don’t come in the kit.
Tuning is a bit different. Here goes.
Bought the 650 kit by mistake, but they are exactly the same except the jets.
650 comes with:
35 pilot, 120 main
400 comes with:
30 pilot, 105 main
Main issue experienced with 650 and the 400 is the jets coinciding with the kit. Had to jump up a pilot and main jet size for myself as well as others with 650’s so the jets are a tad lean out of the box (also depends on your engine and altitude). I’ve got 35 pilot and 110 main (however I suspect I need a 115, but I won’t know until I get a chance to really ride it)
All my maintenance is up to snuff, points, valve clearance, etc. just to note.
All that is good and easy to figure out, do your pilot jet and main jets first because this is where it gets hairy. These kits come with the same needle profiles! Not good. You can get your jets right and drive it fine and all, but the midrange off-idle is rich and bogs the engine and can kill it if you snap the throttle. The profiles are off with both kits. ( I’ve compensated a bit for this by raising the clip and increased idle so it’s not so bad, but it only covers up the initial problem). I did some more digging, and found someone who diagnosed this issue and landed on jjm needle to really get it.
Currently, I don’t have time at the moment to check the needle profile to let you know what comes with the carbs, but I will be doing so at some point very soon. I want a starting point before buying needles, and I’m trying to get into contact with the guy from the 650 forum that has it figured out so I can see how things pan out. I’m assuming profiles will be similar as the jetting isn’t to far off.
I’ll keep everyone posted as I make progress, I figure it will come in handy when someone else is looking or is just “dealing” with how they are like I have been until I got fed up. I want throttle response and smooth performance.
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