Topic: Carb Wizards... I need your sacred wisdom

[Adam_F]

for your clear tube method, you'll need to heat and stretch a section of clear tubing, or cut it at a taper to jamb or twist it in the drain screw hole, before turning on your fuel at the tank.
the 350F drain is the same.

Yeah...  Figured that would be the case.  I have some various sizes of fuel line, so I'll see if anything can fit in there nice and snug.  When I pull the carbs to replace the float needles, I'm going to try to prop the carbs up level (as if they were installed on the bike), connect the gas tank from above, and check the fuel levels before I actually reinstall them. 

read here about clear tube checking float level.   i'm sure there are other easy ways too

http://forums.sohc4.net/index.php?topic=135470.25

Thanks!

[Adam_F]

Well...  my new float needles and seats came in the mail today.  When I ordered them from parts n more, it said that they were OEM.  But when I opened the package they were wrapped in Keyster wrapping (and didn't have the Keihin stamp on the seats).  I read around the forum and from what I read, while not ideal, they should work.  So I figured I'd give it a whirl and install them.

Pulled my carbs and replaced the old needles and seats with the new keysters and put everything back together.  Took a total of about 2 1/2 hours.  Turned the petcock on to prime the bowls while I ran inside to grab my jacket, helmet at gloves.  When I came back two minutes later, this is what I found:



  Fuel EVERYWHERE.  I mean, I've forgotten to turn off my petcock in the past, but I've never seen anything even close to this.  It was literally pouring out of the overflow tubes, the airbox drain....  I felt around and noticed that carb #1 had fuel on the outside of the bowl.  I figured maybe the problem lied there.  I was able to get the bowl off with the carbs on and check things out.  On the inside everything looked fine.  I held the float in place and turned on the fuel to make sure it would stop like it should...  Must've been a different carb.

Anyone have any insights as to what happened?  Think that a float was just stuck so the gas just came pouring out without stopping?

Thanks...

[harisuluv]

saw no mention at all of measuring the float level, did you set them at a particular height?

[seanbarney41]

almost anytime I remove carbs, and especially if any work is done with the floats, the needles will not seat initially.  Usually just need to give the bowls a wack with a screwdriver handle or something of that nature.

[Adam_F]

saw no mention at all of measuring the float level, did you set them at a particular height?

Sorry.  In my haste I left out some details.  Yes, I set the float heights to stock 22mm at the point where they just touch the needle (before compression, carbs on their side). 

I gave it some time, went back out and put in new plugs (as the others where soaked with gas).  The bike fired right up and I took it around the neighborhood and on the highway for about 30 minutes.  Runs great, but I'm still having troubles with my idle...  I pulled the plugs and number 1 is still rich (black and sooty), which could be my problem.  I was hoping the new float needles would solve this.  I had synched them up previously, but will try it again.  I have the air screws all set at the recommended 1 and 1/2 turns out.  Could it be that I have worn slide needles?  Everything is stock (jet sizes and needle position, referenced a chart found on this forum posted by two tired).   

Replacing the float needles was the last thing on my list to try.  Any one have any further ideas?

almost anytime I remove carbs, and especially if any work is done with the floats, the needles will not seat initially.  Usually just need to give the bowls a wack with a screwdriver handle or something of that nature.

Yeah, figured that could be the problem.  Good to know that it happens.  Never experienced it with working on the carbs before... But I guess w, new needles.....

[goldarrow]

With new aftermarket float valves, stock float height is no longer valid

[Don R]

Yes what he said ^

[trueblue]

Another thing to check is that the tang on the float doesn't have a little dimple where the fuel needle sits on it.  It can cause it to catch randomly and flood one cylinder.  Normally a gentle tap on the float bowl will free it up.  If it has a dimple a little fine sandpaper will cure the problem, just blend the divit into the rest of the float tang .

Have you done this yet?   

[lucky]

Be careful with strep throat people.
 IT can kill you because it attacks the heart muscles.

After three days see the doctor.

The creator of the muppets TV show died from this .
He did not get to the doctor in time.

[calj737]

Have I entered the "Twilight Zone" or what? Would someone please ask Rod Steiger to focus on the topic of overflowing carbs and slide needles.... WTF!

[Adam_F]

Another thing to check is that the tang on the float doesn't have a little dimple where the fuel needle sits on it.  It can cause it to catch randomly and flood one cylinder.  Normally a gentle tap on the float bowl will free it up.  If it has a dimple a little fine sandpaper will cure the problem, just blend the divit into the rest of the float tang .

Have you done this yet?   

I did check that.  Didn't notice anything. 

I still need to do a clear tube check of the fuel level.  Out of curiosity.... Lets say everything is where its supposed to be and I am still running really rich on a cylinder.  What would that indicate?  And how could I lean it out a bit more so my plugs aren't so black and sooty?

Thanks!

[flybox1]

Another thing to check is that the tang on the float doesn't have a little dimple where the fuel needle sits on it.  It can cause it to catch randomly and flood one cylinder.  Normally a gentle tap on the float bowl will free it up.  If it has a dimple a little fine sandpaper will cure the problem, just blend the divit into the rest of the float tang .

Have you done this yet?   

I did check that.  Didn't notice anything. 

I still need to do a clear tube check of the fuel level.  Out of curiosity.... Lets say everything is where its supposed to be and I am still running really rich on a cylinder.  What would that indicate?  It would indicate your jetting is too rich.And how could I lean it out a bit more so my plugs aren't so black and sooty? depends on what throttle position you are testing.  if at idle, adjust your mixture screw.  low to mid throttle positions adjust your pilot jet and needle clip position WOT, adjust your main jet size.
Thanks!

Your float valve and seat have nothing to do with a rich or lean condition.  Itonly controls the flow of gas into the bowl.
Float height, mixture screw, jet size, and needle clip position control mixture

with any NEW or aftermarket needles and seats, you should set the float height as recommended, but also verify the bowl fuel level (clear tube method)  as new needles often contain harder springs, which will shut off the flow of gas SOONER, potentially leaving you lean.   Only the clear tube method will show you what, if any adjustments need to me made.

[goldarrow]

i've seen 5 different variations of float valves, at least for early 750 carbs, all look much the same if not paying close attention.  upon close camparisons, they are slightly different heights, spring rate, taper angles, etc.  these will affect your rich/lean condition to some degree

[Adam_F]

Your float valve and seat have nothing to do with a rich or lean condition.  Itonly controls the flow of gas into the bowl.
Float height, mixture screw, jet size, and needle clip position control mixture

with any NEW or aftermarket needles and seats, you should set the float height as recommended, but also verify the bowl fuel level (clear tube method)  as new needles often contain harder springs, which will shut off the flow of gas SOONER, potentially leaving you lean.   Only the clear tube method will show you what, if any adjustments need to me made.

i've seen 5 different variations of float valves, at least for early 750 carbs, all look much the same if not paying close attention.  upon close camparisons, they are slightly different heights, spring rate, taper angles, etc.  these will affect your rich/lean condition to some degree

Thanks Gold and Flybox.  I did notice subtle differences in the needle and seat.  The needle was slightly larger than the stock, which made the floats measure higher (or lower depending on which way you look at it) and require adjustment of tang to get back to 22mm stock setting.  I will verify the actual fuel level via clear tube. 

As I mentioned previously... everything is set to stock specs with stock parts (muffler included, other than the new float needle and seat).  If I still remain rich after a successful float check, what would be a good plan of attack?  Change needle clip position (up or down)?  Different jet sizes? 

[flybox1]

If I still remain rich after a successful float check, what would be a good plan of attack?  Change needle clip position (up or down)?  Different jet sizes?

Rich where?  I think youre trying to find one fix-all for a general rich condition.
You have to tell us WHAT THROTTLE POSITION you are in as each position is being fed fuel by a different component(s) of your carbs.
0 (idle),   1/4 turn,  1/2 turn,   3/4 turn,   WOT

read up on plug chops, and how to do them.  this might shed more light on the parts of the carbs working at varous throttle positions.  How to accurately test for rich/lean conditions, and what adjustments need to me made

[Adam_F]

If I still remain rich after a successful float check, what would be a good plan of attack?  Change needle clip position (up or down)?  Different jet sizes?

Rich where?  I think youre trying to find one fix-all for a general rich condition.
You have to tell us WHAT THROTTLE POSITION you are in as each position is being fed fuel by a different component(s) of your carbs.
0 (idle),   1/4 turn,  1/2 turn,   3/4 turn,   WOT

read up on plug chops, and how to do them.  this might shed more light on the parts of the carbs working at varous throttle positions.  How to accurately test for rich/lean conditions, and what adjustments need to me made

Yep, sorry.  Still learning.  I haven't done the plug chop test at different rpms, but I believe that I am only overly rich at idle.  Here's my reasoning...  When I ride around the bike runs great.  Pulls through all gears and rpms w no hesitation or flat spots.  No stumble off idle unless the bike has been idling for a minute (like at a red light, and the stumble is very subtle...)  I keep my rpms around 5k when riding around and try to get them up to or past 7k every here and there.  After such riding, I'll hit a stop sign or red light and the bike will idle great.  But after maybe 20-30 seconds, the idle wants to drop and the plug on cylinder 1 in particular is black and sooty (I've only checked plugs at idle).  I'm very happy with the way she runs other than my issues at idle.... 

[flybox1]

all of the charted carb components effect air/fuel mixture at different throttle positions.
to get your jetting right, you have to test each throttle position(plug chop) and read plug deposits to determine a rich/or lean condition.  then you make the changes for that throttle position.
then you move to test the next throttle position.
Start with the main jet (WOT) plug chop, making the necessary changes based on your plug deposits, and move to the next lower throttle position and repeat the test, until you finish with the idle chop (mixture screw)