XJ650 Carb "Pilot Mixture" settings

In my manual, it states that "no adjustment of the pilot mixture" is recommended. Unfortunately the XJ650 I acquired had one of mixture screws missing (see attached photo; I am not referring to the Cold Start Plunger). I noted that Carbs 1 - 3 screws are set at 4 complete turns OUT (ie if the screw was closed by turning fully clockwise, then then screws were set at 4 turns out). This is past the maximum spring setting, so has anyone have a ball-park figure as to how many turns these screws should be turned (anticlockwise from fully closed position) for a running position? I have a vacuume setup for balancing, but suspect 4 turns out is why the bike ran rich (before I dismantled it). Thanks, Stephen.

 

After the bench synch, set the mixture screws 2.5 turns out.
This is a good place to start your tuning.
Unless your ride has been modified 4 turns was probably too rich.

 

Looks like the PO was into those carbs. I would advise to take them apart and see what else is missing or in the wrong place. Check the placement of the air jets and such. Chacal should be able to help you with the little parts for your pilot screws. There is o-rings and washers under the pilot screws.

 

Agreed. They were probably 4 turns out to compensate for another problem.

Start with your mixture screws at about 1 3/4 turns. The 80-81 have a coarser thread than the later models.

 

Lookind at the picture you must have removed the enrichment plunger and linkage. Look for RickOMatic's old school carb cleaning along with the clunk test.

 

THIS is where you drill out those brass anti-tamper plugs, right?

 

yes - If you still have them

 

Other than the 4 of these, there aren't any others to drill out, right?

 

Shouldn't be. The caps were to prevent owners from messing with the mix. The factory set them to meet emissions regulations.

 

Correct, Sushi.

I have a spare rack that needs to have these drilled out.

 

I'm going to look at my original rack to see if they were already drilled out. I'm thinking the guy might have altered the jets after podding and supertrapping my bike.

 

THANKS - XJ650 Carb "Pilot Mixture" settings

Hi guys, A huge thank you to you all for your advice, it is appreciated. I have been working with Chacal (XJ4ever) and he has been great with what parts will probably be required and able to supply them all. Needless to say, with my Carbs looking in such a poor condition I will be completely stripping them and refurbishing. Regards, Stephen.

 

You won't regret it - I pulled mine twice before I broke down and did a complete rebuild. Huge difference.

 

if you drill the caps off don't get carried away, like i did

 

Polock I don't know if I'd admit to that much less take pictures

 

not just once but twice
parts carbs, once the heads are so mangled and the easy-out snaps there's not much to do but try a Mr. Science project
ream the hole to 5/16 .450 deep put a plastic bushing in it and drill it so a new needle will self tap into the plastic
it might work, it probably won't but it's a challenge now
then i start on the float posts

 

I find a great way to get float screws and brake mc screws is to take a small nut and place it over the philips screw. I then take a my cheapy welder and arc straight through the middle of the nut for a fraction of a second. This usually welds the nut to the screw and I can extract with a wrench.

 

Sick