My ds650 is running way too rich between 3500 - 4000 rpm's at roughly 5/8 - WOT. It is mostly stock except: 22" tires and uni-filter. I dropped the front sprocket down to 14 teeth thinking maybe the higher gear ratio was causing the problem. I also purchased the unifilter thinking the stock filter was the problem (needed replacing anyways). Neither made a difference. I replaced both spark plugs and cleaned the carb twice. It has the 165 main which I believe is stock. I recently moved from sea level to 2800 ft but I'm not sure if thats when the problem started. Above 4000 rpm it runs very strong. Below 4000 it runs good until you open it up. It's not just a slight rich condition. The whole bike shakes and hardly accelerates unless you let up on the throttle.
I also checked the choke to make sure it was closing all the way and checked the float height. It also seems like if I ride it harder (higher rpms) and then slow down below 4000 rpms the condition is better temporarly. I have done alot of deep water riding so maybe electrical? It feels like too much fuel though.

Sorry about the lengthy explanation. I have been a frequent reader of this forum for years and this is my first post.

Nate

 

Hi, The first thing I would check is the rubber diaphram on the top of the carb. if it gets a hole in it, it doesn't open like it should, & can partially choke off the supply of air to the engine.

 

Diaphragm looks good, needle is on the 4th clip down from top.

 

how many turns out, is the adjustment screw? (bottom of the carb, right beside the bowl) also, make sure the tubes coming out of the airbox aren't plugged. you could just pop the airbox lid off & blow through the tubes. it should run better with the lid off, since its running too rich.

 

2.5 turns

 

its not going to fix the problem, but raising the clip, (lowering the needle) all the way, & leaving the airbox lid off will help. Where are you located?

 

I'm in Asheville, NC.
I considered raising the clip but then I thought of two things:
I would be leaning out my cruising throttle A/F mixture.
and
There is obviously a problem somewhere because it ran good at one time and the bike only has maybe 50 hours on it.
Thanks

 

If its running that bad, I don't think you have to worry about leaning it out too much.
I went back & re-read your first post.. Thats exactly how one of mine ran when I had a bad diaphram. It definately seems like its not getting enough air. taking the airbox lid off should help a little too.

 

Well......I took the airbox lid off.......It stopped the rich condition but didn't have a whole lot of power. I put the airbox lid back on and the condition is GONE......no idea why......Hopefully it's not intermittent........Thanks justme

 

you're welcome.