Author Topic: Carburetors and their various parts,internal and external with pics.STICKY PLZ  (Read 59756 times)

Offline ben2go

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This thread is seriously helpful in getting my bike tuned up right. The thing I'm wondering because I can't see it in the picture is about the head on the mixture screws. Are they flat head, phillips, hex? I'm trying to see if I can turn them without taking the carb off yet again

They should be flathead.Make sure the covers have been removed.You may already know this.


While we are on the subject of mixture screws.I have found that the DR125SE, 200SE, DR250/350,AND DR650S/SE use the same mixture screws that the 89-00 GS500E usues.So that means we can run the Kientech extended mixture screws.You will need to order two as the bikes the are listed for are single cylinder single carb bikes.They are $15 each or $30 for a pair.
http://www.kientech.com/ExtendedFuelScrews.htm
« Last Edit: August 05, 2012, 04:22:54 AM by ben2go »
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Offline mustangGT90210

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This thread is seriously helpful in getting my bike tuned up right. The thing I'm wondering because I can't see it in the picture is about the head on the mixture screws. Are they flat head, phillips, hex? I'm trying to see if I can turn them without taking the carb off yet again

They should be flathead.Make sure the covers have been removed.You may already know this.


While we are on the subject of mixture screws.I have found that the DR125SE, 200SE, DR250/350,AND DR650S/SE use the same mixture screws that the 89-00 GS500E usues.So that means we can run the Kientech extended mixture screws.You will need to order two as the bikes the are listed for are single cylinder single carb bikes.They are $15 each or $30 for a pair.
http://www.kientech.com/ExtendedFuelScrews.htm


I'm definately going to have to check out those extended ones. If the covers have not been removed, how does one go about taking them off? Pop them out, jab at them, go inside the carb? I'm trying so hard not to take the bike apart again
'93 GS - Clubmans - '04 tank/seat - Custom "slip" on - Airtech fender - Drag Specialties speedometer - GSXR drag bike grips - GSXR pegs - Lunchbox - Re-jet - Sold!

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Offline ben2go

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This thread is seriously helpful in getting my bike tuned up right. The thing I'm wondering because I can't see it in the picture is about the head on the mixture screws. Are they flat head, phillips, hex? I'm trying to see if I can turn them without taking the carb off yet again

They should be flathead.Make sure the covers have been removed.You may already know this.


While we are on the subject of mixture screws.I have found that the DR125SE, 200SE, DR250/350,AND DR650S/SE use the same mixture screws that the 89-00 GS500E usues.So that means we can run the Kientech extended mixture screws.You will need to order two as the bikes the are listed for are single cylinder single carb bikes.They are $15 each or $30 for a pair.
http://www.kientech.com/ExtendedFuelScrews.htm


I'm definately going to have to check out those extended ones. If the covers have not been removed, how does one go about taking them off? Pop them out, jab at them, go inside the carb? I'm trying so hard not to take the bike apart again

You very gently and carefully drill a small hole in the center of the caps.Then thread a small screw into the hole about 1/16th of an inch.Last,take a pair of pliers and work the screw back and forth while pulling.This should pop the caps right out.If you drill to far,you will hit the mixture screws underneath the caps.
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Offline mustangGT90210

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I hope they've been messed with before then! The carbs have been rebuilt before I bought the bike so it would make sense to have already been tuned, right? Hope so.

Thanks for the help  :bowdown: Hopefully my next posts on here can be about how my bike is running great, instead of leaking gas, fix that and now I get a hang up in the throttle when revving and letting it come down and shooting black smoke out the pipe!
'93 GS - Clubmans - '04 tank/seat - Custom "slip" on - Airtech fender - Drag Specialties speedometer - GSXR drag bike grips - GSXR pegs - Lunchbox - Re-jet - Sold!

-94 GSX-R 750 - Sold

-02 SV650 - Crashed, sold for parts

-96 Bandit 600 - Sold

-93 Intruder 800 - bobbed out basket case,new project

Offline ben2go

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I hope they've been messed with before then! The carbs have been rebuilt before I bought the bike so it would make sense to have already been tuned, right? Hope so.It is highly possible that the caps have been removed.Grab a small mirror and look under the carbs.You will either see the screws or the caps.

Thanks for the help  :bowdown: Hopefully my next posts on here can be about how my bike is running great, instead of leaking gas, fix that and now I get a hang up in the throttle when revving and letting it come down and shooting black smoke out the pipe!Good luck.Take your time and clean the carbs really good.When you think you have them clean,clean them some more.

I am going to quote factory pro on how to tune our type carbs.

Quote from: Marc W. Salvisberg
Follow steps in order....First, dial in:

    1. Top end (full throttle / 7.5k to redline -
    Best Main Jet must be selected before starting step 2 (needle height)!
            Select Best Main Jet
        To get the best, most even top end power (full throttle/after 7500 rpm), select the main jet that produces the hardest pull at high rpm.
            If the bike pulls harder at high rpm when cold and less hard when fully warmed up, the main jet is too large. Install a smaller main jet and retest until you find the main jet that pulls the hardest at high rpm when fully warmed up. This must be done first - before moving on to the other tuning ranges.

            If the bike doesn't pull well at high rpm when cold and gets only slightly better when fully warmed up, the main jet is too small.
                In order to properly tune the midrange and low rpm carburetion, THE MAIN JET MUST FIRST BE PROPERLY SELECTED after 10 to 15 minutes of hard use!

                        Do not pay too much attention to the low-end richness when you are changing main jets - you still need to be using the main jets that produce the best power at high rpm. You will deal with the low-end / cruise later - after step 2.

    2. Midrange (full throttle /5k-7k)

    Step 1 (Best Main Jet) must be selected before starting step 2!
            Select best needle clip position
        To get the best power at full throttle / 5k-7k rpm, adjust the needle height, after you have already selected the best main jet.
            If the engine pulls better or is smoother at full throttle/5k-7k in a full throttle roll-on starting at <3k when cool but soft and/or rough when at full operating temperature, it is too rich in the midrange and the needle should be lowered.
            If the engine pulls better when fully warmed up but still not great between 5k-7k, try raising the needle to richen 5k-7k.
            If the engine pulls equally well between 5k-7k when cooler as compared to fully warmed up, the needle height is probably properly set.

                        Do not pay too much attention to the low-end richness when you are changing needle clip positions - you still need to be using the clip position that produces the best full throttle / 5k-7k power in conjunction with the main jets (Step 1) that produce the best power at high rpm. You will deal with the low-end / cruise next.

    3. Low end (full throttle / 2k-3k)

    Step 1 (Best Main Jet) and Step 2 (needle height) must be selected before starting step 3!
            Float height (AKA fuel level & how to..)
        To get best low-end power, set float height (fuel level) so that the engine will accept full throttle, without missing or stumbling,  in 2nd gear from 2.5k to 3k rpm at minimum.
            Float heights, unless otherwise specified in the installation guide, are measured from the "gasket surface" of the carb body to the highest part of the top of the float - with the float tang touching but not compressing the float valve spring.
            If the engine has a "wet" rhythmic, soggy area at full throttle / 3k-4k rpm, that gets worse as the engine heats up, lower the fuel level by resetting the float height 1mm greater (if the original was 13mm - go to 14mm). This will lower the fuel level, making full throttle / 2k-3k rpm leaner.
            If the engine is "dry" and flat between 2k to 3k rpm, raise the fuel level.
            Example: change float height from 15mm to 14mm to richen up that area.

            REMEMBER, since the main jet WILL affect low speed operation, the MAIN JET has to be within 1 or 2 sizes of correct before final float setting.
                Warning: If the engine is left with the fuel level too high,, the engine may foul plugs on the street and will be "soft" and boggy at part throttle operation. Adjust Floats to raise/ lower the Fuel Level.
                    Base settings are usually given if a particular application has a history of fuel level criticalness. The Fuel level height in the float bowl affects full throttle/low rpm and, also, richness or leanness at cruise/low rpm.
                Reference: a bike that runs cleanly at small throttle openings when cold, but starts to show signs of richness as it heats up to full operating temperature, will usually be leaned out enough to be correct if the fuel level is LOWERED 1mm. Check out and RESET all: Suzuki (all), Yamaha (all) and Kawasaki (if low speed problems occur). Needless to say, FUEL LEVEL IS EXTREMELY IMPORTANT!!!
            If there are low-end richness problems, even after lowering the fuel level much more than 1.5mm from our initial settings, check for needle wear and needle jet (part of the emulsion tube). See Worn Needle and Worn Needle Jet diagram. It is VERY common for the brass needle jets (in the top of the "emulsion tube") in 36mm, 38mm and 40mm Mikuni CV carbs to wear out in as little as 5,000 miles. Check them for "oblong" wear - the needle jet orifice starts out round! Factory Pro produces stock replacement needle jets / emulsion tubes for 36mm and 38mm Mikuni carbs. Click here
    4. Idle and low rpm cruise
            Fuel Screw setting (AKA mixture screws)
                There is usually a machined brass or aluminum cap over the fuel screws on all but newer Honda. It's about the diameter of a pencil.  Cap removal details. Newer Honda carbs have no caps, but use a special "D" shaped driver, usually supplied in the carb recal kit. We do have them available separately, too. 800 869-0497 to order -
            Set for smoothest idle and 2nd gear, 4k rpm, steady state cruise operation. Set mixture screws at recommended settings, as a starting point. For smoothest idle, 2nd gear 4000 rpm steady state cruise , and 1/8 throttle high rpm operation.  (pj tuning information)
            Pilot fuel mixture screw settings, float level (but, you've "fixed" the fuel level in Step 3 - which you have already done!) AND pilot jet size are the primary sources of mixture delivery during 4000 rpm steady state cruise operation.
                If lean surging is encountered, richen mixture screws (turn out) in 1/2 turn increments. Alternative pilot jets are supplied when normally required.
                Pilot fuel mixture screw settings, float level and pilot jet size also affect high-rpm, 0 to 1/8 throttle maneuvers. Too lean, will cause surging problems when the engine is operated at high rpm at small throttle openings! Opening the mixture screws and/or increasing pilot jet size will usually cure the problem.
                    NOTE: A rich problem gets worse as the engine heats up.
                        If the throttle is lightly "blipped" at idle, and the rpm drops below the set idle speed, then rises up to the set idle speed, the low speed mixture screws are probably set too rich: try 1/2 turn in, to lean the idle mixture.
                    NOTE: A lean problem gets better as the engine heats up.
                        If the throttle is lightly "blipped" at idle, and the rpm "hangs up" before dropping to the set idle speed, and there are no intake leaks and the idle speed is set at less than 1000 rpm, the mixture screws are probably too lean: try 1/2 turn out, to richen mixture. Be sure there are no intake leaks and the idle speed is set at less than 1000 rpm!

    Carb Kit Design is a combination of science, art, intuition and and at times, a fair dose of wizardry. There is no dyno that "tells" one how to assemble or modify the carb to deliver proper power and response.
    Perfect Carb Kit TUNING requires patience and perseverance and "reasonable" feel to feel the changes - of which - most motorcycle riders have a good ability to do.
    When a dyno "operator" says he/she has to ride the bike after dyno tuning to do the final tune for cruise smoothness - that's what they are doing. Avoid any dyno operator who says that they don't have to do that!!!
    The only dyno that I know of that will duplicate and visually display the engine smoothness is the EC997 dyno (yes, I know, we make it) - that's one reason why, if you can, you'd like to use one for tuning - a smoother engine IS getting the best mixture. Other dynos claim to "tune to an "A/F Ratio" - probably the biggest marketing scheme in the dyno industry at this time - and they never can equal the quality of tune as designed -
    These tuning kits have been thoroughly tested to ensure easy, trouble-free, optimized performance.
    Please note: If you have installed the kit and gone through the optional screw settings, clip positions and main jets, and still have a persistent flat spot/problem, we ask you to call us. Unique engine / exhaust / filter / altitude / temperature combinations may require individualized setups. We are here to help. The information gained to your solution will be installed in our computerized reference database. PLEASE CALL!
    We ask that upon completion of installation and tuning, that you call us with specifications of your installation, (pipe brand, filters, advancer, altitude, humidity, temperature and final carb settings) to be entered in our TUNING DATABASE. The database allows us to include the "most used" jet sizes and setup specifications in every kit.
    Use (415) 491-5920, (800) 869-0497 or fax (415) 492-8803.

    Thanks!

    Marc W. Salvisberg
« Last Edit: August 05, 2012, 10:17:57 PM by ben2go »
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Offline Jeremyfuhst12

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This post helped me out so much!! Thank you!

Offline ben2go

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This post helped me out so much!! Thank you!

You're welcome.
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Offline aspirin

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I've spent all last year trying different jets and enrichment needle positions (when I found time seeing as I use my bike to get to work). My bike has been lean right from when I bought it and I've been trying to find a solution.

Then I came on here and saw the vacuum port o-ring...something I've never seen before.  Thank you for that photo. The previous owner must've lost it without noticing (there're signs the carbs had been opened before I got it) First thing tomorrow I'm going to call my local Suzuki dealer and get them to order some in for me and then proceed to undo all my changes to alleviate its leanness. I can't wait!

Offline Old Mechanic

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I have a lot of experience with carburetors dating back to my 1937 Ford 5 window coupe (sold a long time ago). My recently purchased 94 GS500E needed a little love carb wise, so I took the easy route and pulled the tank and the tops off the carbs. Everything looked nice and clean. I attempted to pull the slide guides out from the top but decided to not mess with them for now. The left side slide spring was broken in two pieces, so I ordered up two of them, which should be here later this week. I feel confident that that should make the bike run very nice without and further work, but only time will tell.
Thanks to the information in this thread I have a head start in any diagnosis and repairs that may be necessary in the future.

regards
Mech

Offline ben2go

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I have a lot of experience with carburetors dating back to my 1937 Ford 5 window coupe (sold a long time ago). My recently purchased 94 GS500E needed a little love carb wise, so I took the easy route and pulled the tank and the tops off the carbs. Everything looked nice and clean. I attempted to pull the slide guides out from the top but decided to not mess with them for now. The left side slide spring was broken in two pieces, so I ordered up two of them, which should be here later this week. I feel confident that that should make the bike run very nice without and further work, but only time will tell.
Thanks to the information in this thread I have a head start in any diagnosis and repairs that may be necessary in the future.

regards
Mech

You're welcome.Glad it helped.
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Offline Old Mechanic

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On the right side the small vacuum orfice o-ring stayed in place. The left side stuck to the cover and fell off when I took it to my parts container. Thankfully I saw it hit the floor and put it back in place. It would have been one of those situations where you fix one problem and create (grrrrrrr) another! Due to this thread I was aware of the importance of those little suckers and should avoid the "fixed one thing created another" scenario, which can drive even the most experienced to total frustration.

Thanks again for making me aware of those little "traps" that make this a bigger pain than they need to be.

regards
Mech

Offline ben2go

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On the right side the small vacuum orfice o-ring stayed in place. The left side stuck to the cover and fell off when I took it to my parts container. Thankfully I saw it hit the floor and put it back in place. It would have been one of those situations where you fix one problem and create (grrrrrrr) another! Due to this thread I was aware of the importance of those little suckers and should avoid the "fixed one thing created another" scenario, which can drive even the most experienced to total frustration.

Thanks again for making me aware of those little "traps" that make this a bigger pain than they need to be.

regards
Mech

Those things are a pain.I have had them slip out while putting the carbs back together and cause all kinds of problems before I found it.
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Offline rjoyce

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Ben or any one on the post... do you know what the carburetor part part is called that is best described as follows..  an inch and a half copper u shaped tubing that extended vertically on the throttle side ( right) from the vacuum tube area from the top chamber to lower chamber...

picture attached from your initial string

If the part broke off, and part of the tube is in the carburetor housing, any suggestions to pull out? 9 I was thinking small threaded screw or nail head.... I can't find the part in Suzuki Schematics and I need to order the part or modify with metal tubing.

Thank You



[attachment deleted by admin]
R Joyce

Offline ben2go

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The copper tube isn't a replacement item.You will need a new carb body or another set of carbs.
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Offline rjoyce

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got it....thanks for the info... i think I can drill out the remnants and modify with some tubing if that is the case... looks like a 3/32 drill bit might fit... I see the top part of the tubing works with the choke lever..  I'll just have to find small diameter metal tubing and bend it in the shape
R Joyce

Offline BockinBboy

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I am unable to find the thread at the moment, but... there was another member a few months ago that had broken that part as well.  His was broken in half and all of the break was outside of the carb, he was successfully able to JB weld it back together and did not experience further problems with it.  I am not suggesting fixing it this way or any certain way... I am only saying that his example led me to believe it isn't an incredibly sensitive part, but it does have to be there and functional.  I believe this tube is actually internal on the newer carbs, to save others from your current woes I'd imagine, and among other reason I'm sure too.

- Bboy


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Offline ben2go

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Be ware of the internal diameter.If it is restricted,it will cause running issues.
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Offline rjoyce

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Thanks to both replies... so when you say restricted, not any smaller than the size of the current tube... I think I figured away to recreate the 2 inch long pipe at i wider OD ( and a wider ID)   I can drill it out from 3/32 to 5/32 ( closest standard to metric) and hopefully insert the 5/32 copper tubing in each size... the top part choke mechanism would still slide in the tube....  does the tube mix gasoline or air?   with the top being in the chock lever and the bottom being near the top of the float, its unclear
R Joyce

Offline ben2go

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Yes.The inside should be the same diameter and smooth.The tube sends vacuum to the top of the slide diaphragm and vacuum port for sync/balancing the carbs.
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Offline Paulcet

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Yes.The inside should be the same diameter and smooth.The tube sends vacuum to the top of the slide diaphragm and vacuum port for sync/balancing the carbs.

Not for the vacuum port according to the manual.  It is a "starter tube": http://www.familyjones.org/paul/Enrichment%20tube.pdf

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