Runs rich no matter what I do.

Hi there,

So I manage to get my xj650 running. I have already gotten help from members in the forum (thanks!). The bike runs on all 4 cylinders, idles nicely, easy to start. However it starts off sluggish from idle and then surges. So classic symptoms of the bike running rich. All 4 plugs, black and sooty. I played with the mixture screws and they are now all the way in. Still Rich. I checked the float heights 3 times and they are correct.

I did try and synch the bike using a carbtune II. However it would not register anything unless the rpm's were 5K with the restrictors on. With them off they registered but as you would expect the bars were oscillating. I don't know if this is related but I thought I would mention it. I know someone else mentioned the same problem and they tried playing with the air mixture first, than syncing. I tried that too and had no luck.

So any ideas? I did clean the carbs and replaced the pilot and air jets with sudco ones (old ones were mangled). The numbers on the one's they sent said 110 and 40 (stock for this setup) and are for Hitachi carbs. I am now thinking maybe the jets they gave me are bigger than what they say, causing more fuel to be delivered than usual.

Anything I missed that could cause the bike to run so rich? Anything else I should check for? I have tried everything to lean it out with no luck. Appreciate you help!

-skm

 

Main Jets and Pilot Jets reversed.

Main AIR Jet and Pilot AIR Jet Reversed.
Common error if your reference book is Haynes.

See Photo:

 

Wow, so I think that is the problem. Previous owner gave me set up those jets and I never checked them but I know the jets are reversed from what you posted. Thanks! I'll go check it out and report!

 

Update:

Success! Thanks for the info! I swapped the jet the bike no longer runs rich. I spent a good portion of the day riding and getting the mixture screws right. Now she's running much better!. I still need to get a colortune and I think that will get everything perfect. ALso need to sync better. I was having the same problems as the guy who started the "Carbtune Pro" thread. My carbtune wouldn't register any vacuum with the constrictors in until I road the bike for a while. Right now it's a little lean and takes a few minutes to warm up. But it's running! Appreciate the quick responses. Awesome forum!

-skm

 

OK. So now I'm confused. Rick is the photo above the CORRECT installation? I am having a similar problem and this looks like how my jets are installed. BUT my Haynes manual photo also looks just like the photo above..

 

My haynes manual was opposite, although the copy I had was very old (from 1994). They may have updated it since then. The pic Rick posted above is the one I followed and it solved my problems. HOpe that helps.

-skm