A moment for clarification please

[Uncamitzi]

Ok... this should confuse the issue even more.. but it may help me diagnose what I need to do.
History:
I knew nothing about carbs. 30 mpg
I tore carbs apart the first time and replaced all o rings and kinda cleaned the carb: Put it back together and things worked a bit better but still got crappy mileage.
Ran it for a couple of years. 30 mpg
Tore the carbs apart and cleaned the according to the BassCliff web page To the LETTER... (except didn't check the jet sizes ...just cleaned them). Put them back together new o rings (again)
No change... still 30 mpg.
Tore the carbs apart again cleaned jets replaced air screws put replaced all jets with stock jets (mikuni factory marks) except needle jets and slide needles. Used PO's Dynojet needles set at leanest (top slot) notch. Factory nylon washer.
Compression tests #1, 130. #2, 125. #3, 128, #4, 130. ( I know low but serviceable)
air screws lightly bottomed motor idles smooth (no throttle) ... spark plugs #1 & 2 wet #3 & #4 carbon fouled. after 1 minute of idle...

I'll wait ...but MY guess is needle jets valve and needles are leaking (Emulsion tube and slides) and need to be replaced (only things that have not been replaced)

[Uncamitzi]

Can a circle have sides????

yep, Inside and outside......

[Sandy]

yep, Inside and outside......

Even if it's drawn on a piece of paper and sitting flat on the table?

[Killer2600]

Are you running factory intake and exhaust? If so I'd recommend setting the carbs to all factory settings (jet/needle sizes and all) and tune from there.

[Uncamitzi]

Even if it's drawn on a piece of paper and sitting flat on the table?

especially in 2 dimensions... lol

[Uncamitzi]

Are you running factory intake and exhaust? If so I'd recommend setting the carbs to all factory settings (jet/needle sizes and all) and tune from there.

Like I said. Right now everything is factory except the needles. When I put the factory needles back on the diaphragms the plugs fouled and gas just poured through it was terrible. This is why I'm thinking the Needle Jet valves are worn now.

[Steve]

Well, here we go with terminology again.

... air screws lightly bottomed motor idles smooth (no throttle) ...

Your bike does not have "air screws".

The only external adjustment you have is the pilot screw. It controls a mixture, not just air.

Some call it a pilot screw (the proper term), others call it the mixture screw.

.

[Uncamitzi]

Well, here we go with terminology again.


Your bike does not have "air screws".

The only external adjustment you have is the pilot screw. It controls a mixture, not just air.

Some call it a pilot screw (the proper term), others call it the mixture screw.

.

Steve, I know... and you know which screws we're talking about.. The point is they are screwed in to the point of cutting off fuel (if I've gotten that right).... and the bike was idling at 1000rpm. I've since let the bike cool down and when I went to start it again. It would not start until I cracked the enrichment valves (also called the choke incorrectly i'm told) I opened all 4 air, mixture, pilot screws to 1/2 turn from lightly bottomed and took the bike (motorcycle) for a ride and the only adjustment I had to make was to turn up the idle (using the idle mixture knob between the carbs and the airbox) after the bike (motorcycle was warmed up) to let the engine idle at about 1100rpm (+/- 100) according to my RPM gage. I am going to ride it for a bit and see what changes... As always I'll read comments and because I know so little I will listen to all constructive suggestion...

[Steve]

Something is definitely screwy with your carbs.

It is not unusual to use the "choke" when the bike is cool, but the pilot screws are usually about 2.5 turns out from lightly-seated.

There are multiple outlets for the fuel mixture. All of them are at the top of the outlet bore. There is one that is just forward (towards the engine) of the throttle plate, one or two more will be just behind the throttle plate. The last one is closer to the outlet of the carb, that is the only one that is adjustable. In normal operation, the first port mentioned is open all the time, but it can not provide enough fuel for the engine to run, so you have to open the pilot screw to add some fuel (which has been mixed with air). The other port(s) are uncovered as the throttle opens, allowing some transition before the needle circuit takes over. The fact that your bike runs so well without the additional mixture from the pilot screw makes me wonder if you have the correct air and pilot fuel jets.

Here is a side view of the carb so you can see what I was just describing:



.

[Uncamitzi]

NICE DIAGRAM! .... now.... WHY can't I lean my mixture...LOL

(I really mean that is a nice and concise diagram.. I wonder why that isn't in the manuals that I have on line or in print.... where did you get it? )

[Steve]

In the Suzuki manual.

Suzuki GS850G Service Manual

It's page 14-30 in the manual, it's page 301 in the .pdf

.

[Uncamitzi]

Steve, you called it earlier in the thread. Something is, indeed, fouled up in my carbs.. or something. I went for a ride today and was feeling pretty good about gas mileage and performance... noticed a bit of stutter on deceleration but nothing too drastic... Wanted to tweek down the mixture just a bit more... removed the tank, plugged the vacuum hose to the petcock, set up my temp gas supply and started up the bike... I wanted to see if the exhausts were close in temp.. so I took out my infrared harbor fright (sic) thermometer and while #4, #3, #2 were hot 150 degree range... #1 was cold.. 94 degrees. So I figured I was not getting spark.... Spark is fine with current plug and a couple of others that I tested. No fire in #1... but the plug was wet. Compression is 128 psi....

[BigD_83]

NICE DIAGRAM! .... now.... WHY can't I lean my mixture...LOL

Just a thought, but if your bike runs with the A/F mixture screw lightly seated, then I wonder if the tips might have broken off, allowing more fuel through than it should be seeing?

[Uncamitzi]

Just a thought, but if your bike runs with the A/F mixture screw lightly seated, then I wonder if the tips might have broken off, allowing more fuel through than it should be seeing?

Pulled all 4 screws and they are fine... Right now I need to find out why my #1 cylinder isn't firing while it's getting both gas and spark.....

[748cc]

Spark plug cap.