Dies when I give it gas

[NewVisionGuy]

Hey guys.      I have another small problem. Probably as simple as cleaning the carbs or knowing how to adjust them properly.  The bike starts on the first crank every time.  If it's cold, I have to choke it like its supposed to be, and if it has warmed up  I don't need much if any choke at all.  I've got it idling around 1200 RPM's, but when I give it gas,  about 75% of the time, it'll just die.  The rest of the time it'll either rev up fine, or rev up to 4 or 5K and then act like its going to stall.   I set the pilot jets 2.5 turns out, and all the main jets completely in.  I'm thinking these settings could be part of my problem.  Also, I haven't tried to sync them yet.

What do you guys think?

[NewVisionGuy]

OH YEAH.  I forgot to mention,  this only happens if I give it throttle quickly.   If I roll on the throttle slowly,  it seems fine. 

[Extent]

Is your accelerator pump working right?  That's what gives gas to compensate for low airspeed when you quickly whack open the throttle.

Not quite sure what you mean by the main jets being completely in.  The only ones that are adjustable are the pilots on the lower side of the carbs.  You're best off fine tuning those, rather than leaving them at the starting point.  Set them so you get the best idle, then back them out about 1/8 turn from there and set your idle speed back down to 1.3k.

Sync is also critically important, get that sorted out before doing any major troubleshooting (and do it after you're adjusted your pilots)

[NewVisionGuy]

Is there any way to adjust the pilots without  taking the carbs off each time?

[Lucky]

????

i'm not sure what your 'adjusting'.. but you don't pull the carbs to adjust the pilots.  i'll have to see if i still have your number...

[NewVisionGuy]

Which part should I be adjusting?  I was thinking we were talking about the jet located on the bottom of each carb???   #61 in the picture

[Lucky]

they aren't shown because they aren't supposed  to be touched (EPA stuff, bla bla bla.) but they are those pointy screws just above the intakes on the left side.  i'll call you.

[comatt]

The #68 screws need to be all the way in and tight.

Mine was doing the same thing.  I started with getting the pilot jets which are located on the bottom right of each carb, just above the carb boots.  They may be covered with plugs.  Check out Lucky's site:

http://www.xz550.com/bowl.html

I started with 2 1/2 front, 4 1/2 rear fot the pilot jets.  I would make sure it was running good then adjust and check the sync.  I kept going back and forth between the two until everything is running good and adjusted.

After all of that, I just sat in the driveway and adjusted the accelorator pump (#35 on your diagram) by turning the throttle and letting the clutch out.  If it died or sounded like it was going too I would turning the screw one way or another until it pulled good and did not die.  The key is to do very fine adjustments to the screw.  When you are done and the bike starts off great put a dab of loktite on the screw so it will not move.

After all of that I turned my mixture screws out just about 1/8 of a turn and now it is perfect, well atleast better then it was.  These procedures may be different depending on where you live.  I live in Denver so teh altitude I'm sure has a big effect.

If you need more help PM me and I'll try to talk you through it better.

Matt

[NewVisionGuy]

Yeah  the carbs motorplow gave me still had the caps.   I think i've got those adjustments pretty close  but  the sync is still way out.    I'm going to Home depot tomorrow morning to collect the parts to make one of motorplow's "homemade" manometers.  I'll sync it up and see where I go from there.


Just out of curiousity,  I noticed that the pressure coming out of the right side exhaust was noticably different from the pressure on the left side.  Is this just because the carbs are out of sync  or  could this mean something worse???



Comatt,  I think I know the adjustment you're talking about on the accelerator pump.  I think I'm going to pull the carbs and put a new diaphram in  just in case.  I have a spare since I got two with my rebuild kits.   I'm assuming that during this Accelerator pump adjustment process  I should have the bike on level ground?.?.?.

[Lucky]

so we are all on the same page here: (and the manual is mislabeled)
#50 are the pilot air jets
#61 are the pilot fuel jets
#41 are the main jets
the pilot mixture screws are not shown

the accelerator pump almost never needs adjustment unless someone was screwing with it.  max length of the rod is 60mm from the bend to the lever.

there is no part 68...

[NewVisionGuy]

I'm with you that far.    So what you're saying is that I should sync the carbs and get the mixture screws adjusted   and then if it still  has the same problem  change out the diaphram and check the accelerator pump adjustment.  I would think this hasn't been messed with  since I had to remove the  plugs to get to the mixture screws.

[Lucky]

if you have stock exhaust, left & right sides mix, so you cannot diagnose seperatly.

if you have seperate exhausts, like Macs, you can use them to get an idea of which cyl is doing what.  on these exhausts, if they 'feel' different then it is a very good indication that the carbs are not fueling the bike equally (either out of synq or other problems with the carbs.)

[NewVisionGuy]

Alright,  well  I'm pretty sure my exhaust is stock

[MotorPlow]

Blue, your exhaust is stock. The front and rear exhaust mix in the connector plate behind the center stand. IF the pressure coming out of each exhaust pipe is that different, I wonder if a critter has made his home in the tailpipe during the time that the bike was sitting. Your exhaust is in excellent condition, so you can rule out anything rusting through.

The carbs that we put on your bike came from a bike that had 3600 miles on it, I doubt that much of anything was touched or adjusted on those carbs. Probably why it started with out any adjustments.

Have you resealed your YICS yet? Remember when I checked that, it had a leak side to side: http://www.xz550.com/YICS.html

[NewVisionGuy]

Lucky had suggested plugging the YICS lines until I get it sealed.       I'm going to Home Depot to build one of your manometers  on Sunday so I'll try to stop by the parts store and get the stuff to seal the YICS up. 


And Yeah  the pressures are  a lot different.  One is a soft puff on my hand.  there other is  quite a bit more forceful.    If there is by chance  a little critters nest in the pipe    how might I get it out without damaging the exhaust?

[MotorPlow]

Don't worry about the critter nest, if there is one, it will burn its self out over time. In the mean time, you might want to check the compression in each cylinder. Advance Auto has a compression tester guage, just make sure you get the one with the correct metric size for the Vision spark plug hole. Bring a spark plug with you to match it up.