650/X-2 SBN44 tuning help

[pepperson4]

so i have a js550/650 conversion. has a milled head at 180psi, westcoast pipe, OP vortex FA, sbn44 carb. Im running a 2.5 needle seat, silver spring, 120 low, and 150 main jets. I just put a aftermarket gutted waterbox in it, and now it starts fine everytime, but when you rev it it kind of sputters a little, throttle feels mushy. and when i take it out it barely plains out and feels like its hitting a rev limiter at real low rpms...im stumped. any help would be appreciated!
http://www.youtube.com/watch?v=UwRCHxHtKu8&feature=youtu.be

 

[Snivilous]

Where are your screws set and what altitude are you at

 

[pepperson4]

elevation is 770ft, and im at 1.5 turns out on high, and the low screw is just in the middle, since i can only adjust it about 90 degrees each way.

 

[hornedogg79]

jets seem a little big to me. Pull the black plastic piece off your low speed adjuster. There's a screw head under there.

 

[pepperson4]

ok ill try that, but isnt the low speed screw for the idle circuit? it sill should be running normal top end though, but it gets worse and worse the longer you ride, at the beggining it runs decent?

 

[Snivilous]

Lean it out, if it's rich then it might bog down more over time if it can't burn all the fuel.

 

[pepperson4]

ok will do, ill try when i get of work and report back, thanks guys.

 

[hornedogg79]

http://www.mikuni.com/pdf/sbn_manual.pdf

It's probably loading up the plugs with too much fuel. Does it smoke heavily? Are your plugs black and wet? The last 650 I had with a single 44 SBN and coffman pipe had 118 low and 135 high If I recall correctly. My 701 with a bpipe and single sbn 44 has 120 low and 145 high. Also make sure you don't have exhaust leaks.

 

[pepperson4]

yes it actually does smoke a decent amount. and i checked the plugs and they are black and wet...lol, time for new jets i suppose?

 

[hornedogg79]

Lean it out first. If you get down below a half turn out on your high or low adjuster then maybe you'll need smaller jets. First thing you need to do is find out what your low adjuster is set at right now. Take that safety cap off and turn it in gently till it stops counting the turns. If it's more than a half turn out then you have some adjustment room left.

 

[pepperson4]

ok i put a 1.5 ns in it, a 105 low and a 130 high, and it revs much crisper on land, and when i threw it in the water, and started it, it ripped out of my arms! so i continued to idle out of the channel, and went to give it gas, and blahhhhhh blahhh blahh wwwaaaaahhhh blaahh, thats the sound lol. it barely gets on plane and sounds like its running on 1 cylinder. its not a carb problem. im pretty sure its a bad cdi?