Tuning carb

[crackerkorean]

When my bike revs it slowly revs down and it was suggested tat it might have a vaccume leak.

I was wonring would running rich do the same thing?
How do I lean out the mixture?

[zore]

Did you have to raise the idle recently?

[crackerkorean]

Its pretty much where I left it and it idles ok at about 1200

[Lucky]

first, if you have a vacuume leak, then it is already running lean. think about it: a vacuume leak allows additional air in at the leak, leaning out the mixture, so you don't want to lean it out further.

second, that symptom is typical of a YICS that has an INTERNAL leak (see my site for testing details).  the reason this causes a slow return to idle is that the YICS has 2 seperate chambers, when a leak develops between these two chambers, your providing fuel to each cyl from Both carbs.  like they had a common intake.

A carb that is out of synq can produce the same symptoms, but it has to be way out of synq, also, since you have exhaust dammage, it's possable that is affecting the fuel flow thru the system.

mixture is adjusted bu adjusting the pilot screws. they DO NOT change the mixture ratio, they adjust the amount of mixture bypassing the throttle plates. mixture ratio is adjusted by changing jet sizes.

--Lucky

[crackerkorean]

right now the bike is running rich.

I do not have a YICS on there
Could that also cause the problem?

The exhaust is fixed it was just bent about 1.5" in

I will not mess wit hthe fuel air muixture.

Mike

[zore]

I'd do as lucky said, and check the yics box for leaks.  It's pretty easy to do.  When the bike fell over, it may have jared it enough to knock something lose.

[Lucky]

adjusting the pilots & carb synq should be considered normal mainenance on a bike this old

[YellowJacket!]

Mike,

Make sure that the ports at the base of each cyl where the YICS hoses would go IF your YICS was in place are tightly capped off.  I uses a piece of fresh vacuum hose and sealed it with a small bolt then placed it over the port.  Even if the YICS is off, these ports still constiture a vacuum leak if they are not tightly sealed.
Hint...check them both.  I just assumed that since one of my ports was tightly sealed that the other one would be too.  Well, guess what..it wasn't.  After plugging the rear cyls YICS port, everything was fine.
Also, can't remember what you said about your carbs, but I think you mentioned that they were both recently dipped.  If they were dipped, that means that they were taken apart and there could be a leak in the gasket between the upper and lower parts of the carb.  Also, if they were dipped withthe air jets in place, any rubber grommets could be degraded.
Furthermore (sounds better than also), the rubber boots that are between your carbs and intakes could be cracked or dry rotted which will cause a huge leak on one or both of the intakes.  These can be repaired with liquid electrical tape (I think I remember someone calling it "luckys electrical tape but thats not a brand name, just a favorite of our lucky here...correct me if Im wrong Pete)  I literally painted the stuff on each boot and it was enough for me to get the bike running decent.  Ultimately, I got new boots ($45.00 each from DGY Yamaha... www.dgy.com )
Anyway, hope this helps.

David

[Lucky]

what i originally reccomended was streching bicycle inner tubes over the intakes & sealing the edges with rtv.  this was reccomended to me by another ROVer loong ago. i never tried it. i've replaced the intakes with good ones since then.

what seems to be the prefered repair now is using Liquid electrical tape (i don't know the brand name, but the probably sell it at Home Depot)

--Lucky