Hi to all
I have a 2001 ds650 with a hmf slip on and K&N filter. I went out for a ride with my budy today and when I hit the gas from a stop or slow roll it coughs and sputters, but if I feather the throttle I can get it to rev around 7480 rpms and thats it no more. I started with a 180 main jet clip in the lowest slot air screw2.5 turns out,and I could only get it to 6800 rpm, so I changed to a 200 main jet everything else the same as before and thats when I could get it to spin about 7480rpms. Am I running to rich? Any help would be great because it sucks not being able to open her up. Thanks in advance.

 

have you tryed to inspect the plug yet?

 

Go pull one of your spark plugs. If you see white on the electrode your lean, if you see black your rich.

 

If all you have is a HMF and K&N you should have a 170 to 172.5 main jet and needle in the 4th groove. You can fine tune it from there.

 

Exactly...200 is way to fat for just the mods you have listed. Fat and lean act almost the same. You just don't have the top end you should. Lean runs hot and is VERY dangerous. Rich is lack of top end power and runs cooler. At least thats what the GPS tells me when I run the same hill in both of those cases.

 

OK guys
Heres what I did. I put the 180 main back in it and moved the clip up 1 more notch so now it is in the second from the bottom notch.Now it pulls hard all the way up to about 7550 no coughing or sputtering at all. I live in northern Mn 10 miles from the canadian border my elevation is 600-1000 ft somwhere in there. Is the 180 main jet still plenty rich so I dont have to wory about hurting anything? And how do you tell the difference between a rich bog and a lean bog? I pulled my plugs and the very bottom of the plugs where black but the white electrode part was white. Can anybody help me in the rigth direction. Thanks for any help.

 

With your mods a 175 is the biggest main I would put in it.

 

with your mods I would say 180 is still to fat. Prolly around 170 to 175 would be correct.
Sorry but i can't tell ya the diff between a rich or lean bog.

 

i'd also say 170 to 175

 

Skidoofan, I live in about the same elevation as you and also have stock bike with HMF. I run 170 Mikuni main with needle in the richest position with excellent results.