2003 DS650 Baja jetting question

[haley521]

Hello, I just bought a 2003 ds650 baja addition. It has a HMF slip-on and K&N filter. It sputters like crazy down low and seems to run a little bit better with the choke pulled out half way. I took all 3 jets out and blasted them with cleaner then reasembled. Made a little bit of difference but still not right. Does anyone know anything about these things to give me a good starting point. Im assuming it was jetted for the pipe but I could be wrong. I should have looked at the sizes when I had them out but I didnt. Thanks for any help. Also, what about the plugs? Could a bad plug cause this. Thank you. Andrew

[brian 68]

if all you have done is a slip on . the stock cams /headpipe don't make much down low. the main jets effect the top end. start by checking the air screw. start about 2 turns out, with the engine at idle,
turn the screw in until it starts to run worse, then turn it out until it runs worse, then set it in the middle . run it , try turning it a little each way ,runing it , the main jet should be a 165 stock. it should run there , check the plugs , white go larger, black smaller. . let me know how that goes. also use new plugs.

[brian 68]

has the bike set,? does gas run out of the overflow tube? what is the elevation where you are at? give me as much info as posible. what do you want to do with it? trail /race ect.

[haley521]

Thank you for the reply's. I will put new plugs in and test it . I will also check the air screw. I use this for basically trail riding and our elevation is around 650, ( Central IL.) Thank you. I will keep you posted.

Andrew

[haley521]

Also, The DS has been sitting for a while. I completely drained the tank and then removed all the jets and cleaned them with carb spray. I didnt look at the jet sizes when I took them out. I should have. And I didnt mess with the air screw. Where exactly is the air screw located? This thing starts up very easy and idles around pretty well. As soon as you nail the gas though it falls on its face. The midrange seems ok and then falls on its face again up high. I need to see where the air screw is set at. It has a K&N filter and HMF slip on with no quiet core. It is almost too loud. I ordered the quiet core thinking it would also give me a little more back pressure. Thank you for all your help!!

[brian 68]

the stock rev limiter makes it feel like it fall's on its face . up top.
the air screw is under the carb where it meets the intake boot, there is a hole that goes up to a straight adjustment screw, screw it out for more gas , in for less. if you take the carb back off check the needle position on the slide. for trail riding with stock set up a exhaust that replaces the stock headpipe will give you much more bottom end. but you will lose a little top, depending on the brand. you might want to try a 170, 175 main at that elevation , but try the air screw first

[haley521]

Thank you for all your help! I am going to be wrenching on it Thurdsay so hopefully I will get it right. Will let you know.

[haley521]

Well I think I got it figured out. I bought a Dynojet kit for it. When I removed the existing main it was a 165. I installed the recomended 180 dynojet main and then checked the air screw. It was set at a 1/2 turn out. I got it to run the best at about 2 1/4 turns out. The problem up high is the rev limiter. It hits it pretty fast. It looks the cdi has to happen now. Thank you for all your help. It made it very easy to tear into this thing and get it right. I also put a quiet core in the HMF silencer.

[brian 68]

for ign's big gun, or ron wood's. (cheapest) but reliable. personaly i have ran a vortex for 9 years. and love it, but it's a few coins more