what is a good carb starting point?

[Jimustanguitar]

I have the infamous stumble that every other newby on here asks about and tries to fix without reading the posts that have already solved the issues...

I did my best to read the posts and try and figure out what is happening, but I'm getting stuck... It seems like there are a few different ghosts in the machine and different fixes work for different people. I want to eliminate the variables and start from scratch.

My '82 has an airbox with a flapper that is vacuum operated (no nickels yet), and I just cleaned the heck out of the carbs (did not dip them however) and replaced every vacuum line on the thing. I'm very glad I cleaned the carbs, because they were pretty nasty, and I used 3 cans of cleaner (with the red tube) spraying out all of the passages and little tubes making sure that I had a good strong stream out the other end of all of them. I also discovered that the venturi in one of the carbs was just wobbling around in its throat, its amazing that it ran. I suspect the previous owner thought its clamp was a mixture screw and tried to turn it.

I'm also disheartened that the main jets are chewed up from someone not knowing how to use a screwdriver correctly, which lead me to believe that he changed the jetting also, or at the very least has a chunk of brass in the orifice.

So if I'm starting from the middle of somebody else's unsuccessful experiment... I will be ordering new jets and inspecting the mix needles along with another cleaning, a dipping cleaning. Will hydroseal work, or do I need a better chemical. Name one that I should go get.

How many turns out are the mix needles from the factory seats? I have no reason to believe that after the carb cleaning already that there could be anything left in there, and want to get everything adjusted so that it is a 'virgin' setup to know whether I need to clean better or not after this first dip.

Also, what do you have to move besides the tank and airbox to get the carb to clear the frame, I had a heck of a time getting those carbs in and out, like a puzzle. I don't like puzzles.

Thanks for the help, I'm tryin'!

[Tiger]

Also, what do you have to move besides the tank and airbox to get the carb to clear the frame, I had a heck of a time getting those carbs in and out, like a puzzle. I don't like puzzles.

Thanks for the help, I'm tryin'!

:) The carbs have to be removed from the left side of the frame (as you sit on the Vision).
Once you have the gas tank, air box, choke and throttle cables, gas and vacuum lines removed/disengaged...pull the tabs that hold the wiring loom to the left side of the upper frame out and pull the loom out a wee bit ;)
Loosen the carbs from the rubber manifolds, lift them up and forward, drop the left hand back corner down to the left and swing the carbs so they come out rear carb first...a$$ backwards :o ;D ;D ;D ;D... ;)

                  8).......TIGER....... 8)

[musicweb]

If the carbs are as bad as you say, you should dip them in some Berryman's cleaner, then use some carbclean and air as a final cleanup.

Mine were so bad, I had to get another set and rebuild them.

For the jets, I used the reference from this board:

main= 122.5 ft, 127.5 rear
pilot= 60
pilot air= 130 (use 135's though)

For adjustments, I started at 3 turns out front and rear. Ended up at 2-1/2 front and 1-1/2 rear.
I don't believe all bikes will be the same though.

I still have a very slight stumble around 40mph but not all the time.

[h2olawyer]

The 135 pilot air jets came with the airbox / carb modification - so the upgrade should be running the 135s.

These carbs are a real bear to get clean - and they do need to be very clean

When reassembling the carbs, start with the mixture screws about 2.5 - 3 turns out from lightly seated.  It should start - you will need to readjust them to get the best idle.

Make sure the carbs are synchronized.

The vacuum actuated flapper does not need the nickels - that's for the earlier / non-vacuum flapper doors.

Well cleaned & adjusted carbs should not stumble at all.  I have a fair amount of experience rebuilding automotive carbs and it still took me three tries to get these Vision carbs clean.  The adjustments took a long time as well - the settings are easier to find when the carbs are 'spotless'.

Good luck with them & welcome to the ROV!

H₂O

[Jimustanguitar]

Just ordered new jets of the correct values, as per the upgrade kit, not the factory values. It had them in there, but they were chewed up by whoever installed them, and I think it will free up a few more horsepower to the placebo effect, you know.

Anyway, after going through these things again (I'm going to chase the little tiny passages beneath the butterfly this time, didn't even know they existed an hour ago) I will follow your recommendations on the mix needle starting points, but should I be initially adjusting for idle, temperature, or using my exhaust gas analyzer?

I realize that all three of them are important and need to balance well, and afterwards I will need to resync and readjust again until everything stays put.

So what should I be aiming for... Does anybody know the factory adjustment process, that would be very interesting... What have you done that worked to smooth things out.

Thanks!

[Rick G]

I worked  for an old timer in Salem OR and if he saw you trying to clean a set of carbs with a spray can you were fired!  You cannot do a proper job with carb spray , they MUST be dipped. Get Lucky's CD  or send them to me. I'll guarantee they will work properly.

[Jimustanguitar]

What would it cost to have you go through them?

I think I'll try dipping them myself because I have a 2 gallon dip can of Hydroseal left from when I rebuilt some Holly's for my mustang, but if that doesn't work, I will definitely farm it out.

Let me know, thanks!