Carb mechanic wanted

[chuck hahn]

Thanks for the info about they only effect the carbs at full closed or very evry low throtle. Not one person had ever explained that in the last few days. I was under the understanding that a FUEL SCREW effected the mixture throughout the entire range of throttling. Someone may have but i probably didnt register it cuz i get so upset and rattled by these things..
So heres where i understanding things right now.. The jets that are in now are not the right ones and i am putting the new ones from Z1 in tomorrow. Then I set he pilot to the prescribed 5/8 to 7/8 and then i set the air screws at 1 1/2. At this point they are ready to be put back on and see how it runs then...I think i am grasping it a bit finally. Is there anything else as far as passages or anything parts wise while i have the bowls off? float bodies, float needles anything like that?? point has been taken on float heights already,,thanks.

 

[SqDancerLynn1]

Taking the mixture screws out ? Sometime when they are messed with people will tighten them too much and the point of the mix screw will break off in the carb...
Weather you have a GS750 or a GS1000 The starting carb settings are the same just different jets. SO the procedure is exactly the same.
I would suggest going back and checking to make sure you have 12 volts on the coils and do a mechanical sync on the carbs. YOU need a baseline/ starting point. Back out the idle adjustment screw all the way, make sure the #3 carb throttle plate is completely closed, adjust if needed. Used the idle screw and adjust the #3 carb throttle plate open about 1/8" (use a drill bit), adjust the other carbs for the same opening. Don't forget to back the idle screw back out to aprox idle setting

 

[chuck hahn]

Thats what is known as a bench sync..i know how to do that as well. Thanks. I dont get the feeling the ends are broke oof any screws but hey maybe it wouldnt hurt to check. or if anything got sucked in there too..just a thought.

 

[chuck hahn]

And to Tatu..since others have posted and cleared up my confusion about JETTTINGS and SETTINGS and explained the range of thottle that the pi,ot effect i offer my apology..

 

[rustybronco]

make sure the clips on the needle are in the correct position.

make sure the needles are the correct ones by examining the part numbers on each needle.

 

[waterman]

If you want some carb theory that isn't too deep check out this website. Not bad site for general fixes.

http://www.dansmc.com/carbs2.htm

 

[chuck hahn]

Yes the man at Z1 asked me about the needles and since i hadnt taken then down that far i know i need to verify the number. And as you taught me the standard clip setting is the middle groove.

 

[sachsaca]

If you want some carb theory that isn't too deep check out this website. Not bad site for general fixes.

http://www.dansmc.com/carbs2.htm

This is a great web site, I read all the stuff I can get my hands on. He is pretty practical

 

[rustybronco]

Yes the man at Z1 asked me about the needles and since i hadnt taken then down that far i know i need to verify the number. And as you taught me the standard clip setting is the middle groove.

Not all clips are set in the middle position. you need to check.

 

[chuck hahn]

ooooook...so thats yet another thing i mis understood. and while i am at it i wanna know is there any solvent or whatever to use to get the black soot off these new plugs so i can reuse them to look at till i kinda get a good looking plug? I was thinkk to use a toothbrush to get way down in there with like say some laquer thinner or something..

 

[Guest]

Thats what is known as a bench sync..i know how to do that as well. Thanks. I dont get the feeling the ends are broke oof any screws but hey maybe it wouldnt hurt to check. or if anything got sucked in there too..just a thought.

My thoughts are that you said in a earlier post that you had turned the screw in and out and got no change , that either there is blockage in the screw jets or the tips are broken and causing blockage, also those only control the idle speed to a certain amount about 2000 I believe

 

[chuck hahn]

I justooked at Bikecliffs 8 valve 750 service amnual and i reread it a few times and didnt see the clip setting listed, but i did howver read about bending the tabs to set the float height. The thing i havent ever heard anyone mention is this little tid bit..Start the engine and check the float heights with the engine running.. shows a guage that has lines on it to properly read the float theights while the engine is running..

 

[tatu]

And to Tatu..since others have posted and cleared up my confusion about JETTTINGS and SETTINGS and explained the range of thottle that the pi,ot effect i offer my apology..

It's ok, don't worry about it. If I might offer up a bit of experience about plugs, I have known even brand new ngk plugs to fail and not work again when engines have been flooded, so I would not use fluid to clean them just a gentle wire brush or leave them.

 

[waterman]

Chuck, after a little checking in the carb spec sticky above, it seems there may be a little controversy over the stock carb settings for your 77B. Maybe someone can shed some light on this. I think TCK has a 750B. I hope this doesn't add to your confusion.

BTW, according to both references the needle should be clipped in the third position.

Im finding all this sooo strange because the Suzuki service manual that originally came with my GS750B 1977 say, and the actual settings on the bike were:

VM26SS
Main Jet: 105
Air Jet: 1.1
Needle Jet: P-1
Jet Needle: 5F21-3
Pilot Jet:22.5
Pilot air jet: 1.6
Cutaway: 2.5
air screw: 1-1/4 turns back


but with that information and my engine number (which my dealer verified is original to my bike frame) it would be

VM26SS
Main Jet: 100
Air Jet: .7
Needle Jet: O-6
Jet Needle: 5F21-3
Pilot Jet:15
Pilot air jet: 1.6
Cutaway: 1.6
air screw: 1 turn back

My Clymer manual doesnt give any details at all, I guess they decided not to because of so many variables.....

So what should I believe???

http://motorbikearchives.com/Bike-Tests/Road-and-Street/Suzuki-GS750EN-1979.html

Just found this which had the following excerpt:

The GS750B came with a # 100 main jet, 0-6 needle, 5F21-3 jet needle, and # 15 pilot jet. The GS750C (1978) and GS750N (1979) carburetors were changed to a #102.5 main jet, 0-4 needle, 5DL36-2 jet needle and #15 pilot jet.

What that all means is that the GS750N is leaner at the small throttle openings usually encountered in EPA emissions test modes. The dual-taper 5DL36-2 jet needle is initially leaner, secondarily richer to smooth the transition from idle to off idle, (or from small, steady-state carb openings at low speeds to gentle acceleration, as encountered in traffic). The float level was also lowered between the GS750B and GS750N, from 26mm to 24mm.

 

[chuck hahn]

The whole process i was gonna use was to scrub them with some kind of solvent to get the soot and coolrs off the center ceramic. Then use my compressor to really be sure they are dry and anything in the bottoms gets flushed out.. I have several little toothbrushes and even some brass and stainless steel toothbrushes..

 

[chuck hahn]

I had seen that chart in the stickys..and even at these specs mine arent at either one!! dont figure why this thing falls on its face. The ones that are in RIGHT NOW are 110 mains and 17.5 pilots.The only thing thats the same is the needle jet..

 

[chuck hahn]

After much misreading and misunderstanding terms and functions i think i am finaly getting a grip on this.. Its just so awefully frustrting though!!!!

 

[rustybronco]

Example....

Jet Needle: 5F21-3

what this means in the above referenced carb, the carb uses a needle identified by the number 5f21 stamped on it. the -3 after the 5F21, means the clip goes on the third notch down from the top. if it had been a -2 on it, you guessed it... second clip position down from the top.

 

[chuck hahn]

OK>>that i didnt know either..the needel jet is telling you where it likes to be..Now these are the kinda things i need to know! Thats cool! I like the way you explain things Dale.

 

[Guest]

New plugs should be used... Or at least I would use new ones.

And, ahh.. Rebuild the carbs.
(sorry, had to say it)