I need a Mixture Fixture!

[tbishop11]

I took my 79 XS11 out this Friday for a warm up run to Sync my Carbs and before I made it home my plugs started to foul. I say started too because she was running really rich and when I checked them at home they were real black. However my mixture screws are 3 turns out across the board. And I would think that would have been leaned it out? Am I crazy or what? The Carbs have all been properly rebuilt and I'm running new K&N filters. I'm about to buy a colortune to see If I can set them that way because I'm at a loss. I've never had a bike fight me like this with the carbs. I was thinking that I should have my mixture right before I Sync or am I way off? I know that's a lot of questions but I'm about to loose my mind.

Thanks, and feel free to tell me I'm a Idiot, starting... NOW!

[ccogswel]

You say 3 turns out. Thats rather rich. I think they are only suppose to be 1 and half out. Some say going to 1 and 3/4th to 2 full turns out for pods. If you running rich I bet it's because your 3 turns out. Turn them in and try it again. Some do this. Clean your plugs and put back in. Find a hill. At the bottom ride up it at full throttle and shut the bike off. Come to a stop and pull a plug to see if its black. Some hear do this. It would also help to find a rode that you can pull over on without risk to yourself.
Good Luck!

[81xsproject]

Try leaning the screws out some more by tuning them in a half turn. If they seem better, go from there. I can't see 3 turns out fouling anyones plugs though. You are correct about mixture then synch. The XS carbs are very forgiving, you'll get there.

[DiverRay]

To properly sync the carbs, you need to start with the sync! Mixture screws should be no more than 1 1/2 turns out. If you know the jetting is correct, go from there. I always warm up the bike on the center stand and then adjust the sync. Once I have the sync close, I then go for the mixture screws.
You WILL need to be sure the valves are ALL within spec, the cam chain is adjusted, and the timing is correct BEFORE syncing the carbs. If the plugs are now fouled, you will need NEW plugs. Sorry, but the fuel buildup on the plugs will cause the plugs to misfire, and the sync will not be correct.

[tbishop11]

So I guess that's it. For some reason I was thinking that as I turned them out (counter clockwise) that was going towards the leaner side, and in (clockwise) was richer. So basically I need to go in for lean? Or am I understanding it backwards?

[DiverRay]

You are correct. In is lean, out is rich. There are a few details to it, but that is all you need to know for now. You DO need to find out if it's rich at low RPM or mid-range and high. The mixture screws control low RPM to about 3500RPM. The transition is from there to about 4000 RPM, and then it's the main jet and needle on the slide to about 7000RPM. After that, it's all the main jet.

[tbishop11]

It seemed to run loads better at higher rpms?

[DiverRay]

Then you probably have the correct jets installed. The pilot circuit is the low RPM, with the mixture screws the "final" adjustment to that. I would start with the screws 1.5 turns out, sync if it seems to run well, and THEN do a final adjustment and re-sync. Don't forget a box fan to keep the engine cool while you are doing the adjustments.

[tbishop11]

Sounds good, whats the best way to fine tune the mixture setting once I've done the Sync. Vac Gauge? Ear? Colortune? or Tach (Which is no longer available)

[DiverRay]

You can clip an automotive tach/dwell onto a coil and use it. Jerry did a great write up on adjusting the carbs and it may be in the tech tips.

[tbishop11]

Awesome, I do have a automotive tach.
Thanks for all the help Diver Ray I know from checking the posts that I'm not the only guy your helping right now so I really appreciate it!

[DiverRay]

No problem. I'm just looking at most of the posts and putting my $0.02 in where I can do the most harm, as long as the person at the other end isn't too close!
DO try to find the write-up on the mixture screw adjustment. It's been a year or two since I looked at it, but for someone trying this for the first time it is a GREAT read.

[tbishop11]

I just read the one in the XS info by Ken and it seemed pretty good, and one by Rob Brotherston and Dave Hansen about Syncing, however haven't found Jerry's yet?

[DiverRay]

I may have been thinking Ken, but said Jerry. I'm planning a road trip and will be seeing Jerry on part of it!

[tbishop11]

Glad you told me I'm pretty O.C.D and would have searched for days and days having already found it but never known, well thanks again for the help, it's late and I've got to get some rest before I tackle this project tomorrow.