Dropping bowls and floats without removing carbs?

[onebohemian]

'98 B12.  Can I drop the bowl off of each carb without removing the carb bank?  I've been having a problem where fuel is filling up my crankcase.  I've confirmed I've got a bad petcock as it leaks like a sieve in both the on and reserve positions without any vaccum applied.  Will be installing rebuild kit for that, but obviously I have a needle/seat issue or float problem as well.   Was hoping I could drop the bowls and remove each float and needle, checking the floats and possibly replacing each needle and seat as well without having to remove the entire carb bank.  Is it possible or will I simply be creating more work for myself in the long run?

Thanks,

[PaulVS]

I'm sure everyone's got a different opinion on this... but coming from someone who has done both... I'd take out the carbs.

If you've never removed those float bowl screws before.... lotsa luck trying to get them off while the carbs are still on the bike.  They're impossible.

the only hard part of getting the carbs out is disconnecting the throttle lines, and that's not too tough if you take your time and think about it.

[onebohemian]

Sounds like the carbs will be coming off.  

Another question.  The bike has a stage 1 kit that was installed by previous owner.  I don't know the specifics of the jets, etc. that were substituted for stock.  It's been awhile since I've had my hands in a carb and am wondering whether the needle and seat may be specific to the stage 1 kit or if those are typically left stock regardless of the jets upgrade.  If the needle and seat are something special, are there markings of some kind on the needles that will allow me to replace them with the same needles and seats?  If they are typically stock, I figure I can just get them from the dealer without having to buy entire carb kits????

Thanks,

[Red01]

Float needle and seat assy's stay stock.

But before you go tearing into the carbs, fix the petcock... the problem could be fuel is running down the petcock's vacuum line into the #4 carb and getting into places it doesn't belong that way.

[chupacabra]

You can use a clear line from the drain and hold it straight up then open the drain screw and you can view the fuel level in the bowls.

[terrebandit]

Float needle and seat assy's stay stock.

But before you go tearing into the carbs, fix the petcock... the problem could be fuel is running down the petcock's vacuum line into the #4 carb and getting into places it doesn't belong that way.

Definately do that!

[99er]

The carbs need to come off, if only to help your patience factor. A main jet change is one thing but fooling with the valve and seat and float adjust is impossible otherwise.
If you go in there and look at the seat, you'll see that it sits in there with only the pressure of its o-ring. They should not almost "fall" out. If your petcock has worn, perhaps these o-rings are also worn, letting tons of fuel bypass the needle. My #4 did this and almost ruined a great day at Barber. O-rings at the stealer aren't cheap but at least they're available and are easily replaced. Do that and take the opportunity of cleaning the carbs while they're out.
Your Bandit will thank you. If your mileage is very poor, you may also have the emulsion tube elongation problem identified by Factory. Look through the carb top to make sure the opening is exactly round. If you have stock needles, they've been sawing the tubes to an eliptical shape. Transition running and MPG suffer greatly.
Marc/Atlanta

[97RedBird]

Marc -
  My 96 B6 may have the same problem you mentioned.  What do you mean by "Transition running" in your last message?

Is this the transition between cruise and acceleration?  I am also waiting for a rebuild kit on my petcock.

[99er]

Hi Nathan,
Yeah, that was not the best choice of words. When the needles are effectively raised much too much, as with the elongated wear on the needle jet, they contribute too rich and too early. When you roll on the throttle, it won't be "crisp" because of the richness. If you're cruising on steady throttle, which uses the pilot and needles primarily, and goose the gas, you will likely get a bit of bogging before she takes off.
Have you lowered your needles to where the bike starts exhibiting lean symptoms - hesitation at steady cruise? Do that and then add a shim until it just goes away. That will get you your best "needle" mileage. That's from an old post by Dale Walker and it's worked well for me. Unless you're on teh track, your needle mileage contributes most to your MPG.

Disclaimer: In the end, I'm just a shadetree guy that's been through lots of carbs so take the above advice in that spirit. Playing with carbs on bikes can be a career. Just make one change at a time and evaluate it over the course of 50 miles of more to make sure of its effect, or lack thereof, before taking another step.
Marc

[97RedBird]

Marc,
  This information is very helpful.  Shady tree or not - any experiences others have help me and others diagnois our bikes.

I am beginning to think my needle jets (emulsion tubes) are out of shape, but it's hard to believe at only 21k miles on the OD.  

I do have some steady throttle cruise hesitation when the engine is at full-temp only.  I assumed this was from anything, but the needle height.  From my notes I need two shims under each needle before hesitation is minimal, but it is still there.

The other big key I notice is when synching the carbs I move idle up and at about 1600 RPM it jumps to 2800 RPMs.   I can't get the idle stop to keep the engine about 1700 RPMs so I try my best at 1600 RPMs and hope that is good enough.

[99er]

Hesitation is either ignition (usually fouled plugs) or leaness caused by air leakage or poor jetting. Have you ever had the carbs out for a once-over? I'd remove them and completely clean them with compressed air and a safe carb cleaner. I use non-chlorinated brake cleaner. Make sure your jets are removed when you clean and that liquid freely flows through all passages. On assembly, make sure that all o-rings are present at the carb tops and that, once installed, the clamps are secure. You can spray WD-40 at the intake seams while idling to see if the idle drops. If so, you're leaking.

Get that petcock problem fixed first and make sure your plugs are clean. There may be some lads in your area that can help if you need it. You need to get down here to the hills of Georgia to give that thing the corners it deserves!
Marc

[onebohemian]

In response to question a few months back regarding some petcock problems I was having, a member (Marc from Atlanta?) wrote:

 . . . If your mileage is very poor, you may also have the emulsion tube elongation problem identified by Factory. Look through the carb top to make sure the opening is exactly round. If you have stock needles, they've been sawing the tubes to an eliptical shape.

I pulled the carbs last night because I'm having a lot of idle problems.  First time for me into these carbs although previous owner had a professional installed stage 1 kit installed (I'm told) with airbox mod done.  I'm going to clean them well and put a "kit" into them (which as best as I can tell is only going to be some o-rings and maybe needles/seats).  Here's my questions:

1.)  I can't find any info about the emulsion tube sawing caused by stock needles.  Is there a recall on this?  What can I do to check and/or fix if I've got problem?  Have 15000 miles on bike.

2.) I'm not going to pull carb bodies off of their rack, but this means that I can't soak the carbs in a dip, correct?  The rubber parts on the rack would get eaten by the dip.  Do you guys who clean just buy a can of carb cleaner and spray into holes, etc. and then blow out with air?  Can this method really dissolve the hard stuff?  On the farm 20 years ago, we'd drop the carb body parts into a 5 gallon bucket of cleaner for at least a day.  She'd come out sparkling.

3.)  Haynes seems pretty straightforward so I think I'll be o.k. on the step by step.  Was trying to find more detailed instructions on the internet from anyone who's done it before but no luck so far.  Anybody have any sites for better than Hayne's instructions on dissembly and cleaning?

4.)  Finally, I don't know yet if my pilot screw blanks were pulled out by prior owner.  If they weren't, can I do a good cleaning without removing the pilot screws?  If they were removed, should I take the screws out to clean the hole or leave them be?  I assume if I were to remove them, I just need to put them back in the same number of turns as I took them out (seating them first and then backing them out to where they were set before I cleaned).  Right?

Thanks,

Mark Privratsky
privrat@cpinternet.com
mprivratsky@lindquist.com
Minneapolis, MN
763-226-5565 (cell)

[99er]

Wow, it's been a while. My email alerted me to your message.

Why not take the carbs completely apart? There's not that much to them. I'd split and dip if they're really bad but I've never had to go that far before. Gumout or non-chlorinated brake cleaner and compressed air work well for me. If you're going to have the set off the bike, drill the plugs and remove the idle screws to check for debris.

Factory Pro has some good tuning tips as I mentioned in April:

Tuning CVs:
http://www.factorypro.com/tech/carbtune,CV,high_rpm_engines.html

Emulsion Tubes:
http://www.factorypro.com/products/needle_jet_Mikuni.html

Good luck!
Marc

[tacoman]

Try the petcock first!  A bad one can cause all kinds of problems.  I had an old gixxer with a bad petcock.  I would get erratic idling, flooding, overheating, etc.  I put it on reserve and it ran great.  I think what happens is when the petcock gets worn it allows vacuum leaks.

[onebohemian]

I put a kit into the petcock and it still leaks on reserve.  I think it may have always done this but when the carbs were tight, the gas didn't get past the needles/seats.  Hoping this carb cleaning with new o-rings fixes the problem, although my needles/seats look very good where the rubber point of the needle is supposed to seat.  The rubber o-ring on the outside of the seat look bad though.

Keeping my fingers crossed.

Mark