83 Mixture Adjustment

[inanecathode]

Whats the procedure for doing a fuel mixture adjustment on an 83 vision? If its idling ok with no smoke just leave it be and sync it, or should i adjust the mix and then sync it? I want to keep from breaking/screwing things up if at all possible.

[h2olawyer]

Same procedure as the 82 carbs as far as I know.  I found it to be a viscious circle - mixture, synch, mixture, re-synch.  Took some time, but it eventually gets to where it's tuned spot on.

[motoracer8]

Have the plugs been removed that cover the mixture screws? If not they will have to be removed to adjust. Start with about two and a half turns out from lighty seated, Clockwise=lean, counter clockwise=rich. You should use a manometer, (vacuum gauge) to sync the throttles, set the idle speed at about 1500 rpm to adjust the sync. Then lower the idle speed to 1200/1300rpm to set mixture, I like about 3 to4% CO on an exhaust gas analyzer. If you don't have access to this equipment, you need to adjust to the fastest idle speed. Generaly as you richen the mixture  the idle speed will increase slightly untill it is too rich then it will slow, or lope alittle. Adjust each screw alittle untill you attain the fastest speed, you may need to adjust the idle speed down alittle with the speed screw. Once you have a smooth even idle, turn the mixture screws in (lean) 1/2 turn, This is about as close as your going to get without an analyzer. Valve clearance is important for accurate Syncronization. Hope this helps, good luck.

  Ken G.

[inanecathode]

I cant get it to hold a tune worth crap. Slow return to idle, funky off idle charactaristics. It's acting like it has a vacuum leak but it has none. Both carbs are synced and tuned the best to my knowledge but its still running like trash. Any ideas?

[h2olawyer]

Vacuum leaks, carb boot leaks or dirt in the carbs are the most likely -- assuming your YICS is currently plugged off.  Always best to tune without the YICS hooked up, then add it into the equation after you get the carbs sorted.  You probably already know that, but it's easy to forget when working on your own bike.   ;D

H₂O

[inanecathode]

Yeh, yics is unhooked and plugged.
I have honest to god brand new intake boots still in their crispy yamaha packaging that might be useful on the 83. Im not sure about dipping the 83 carbs, i dont want to break anything. I tried oiling my tach needle and the thing breaks off today :(

[Rick G]

I think Luckys CD covers dipping '83 carbs , I won't touch the things ,as I have no spare parts for them.
The slow return to idle sounds like , either an air leak or  poor sync.

[Brian Moffet]

When I rebuilt my carbs, it was very slow to return to idle until I got the things synced.  That made a huge difference in how they ran.

Brian

[inanecathode]

Thats odd, because as far as i can measure its perfectly synced...

[Kenny]

 Inane - what procedure did you use to check for your vacuume leaks? Is your accel pump working properly? I had one that the ball & weight where hung up and it was leaking extra fuel on the decell.  Try the WD 40 spray to find leaks if it revs up youv'e got one.
              ;) Cheers Ken S.

[inanecathode]

Yeah, i sprayed brake cleaner all over everything and it never revved up. Stuck accelerator pump is a possibility, it acts like the accel pump isnt working with a bog when you apply throttle judiciously.

[motoracer8]

If it sounds like it's running on one cylinder when returning to idle, that is syncronization, also check for dirty pilot jets. Check the throttle shafts for air leaks. Back the idle speed screw out to where it has no effect, if it still returns slow you most likely have an air leak.

  Ken G.