sleepless nights in carbville

[captrise]

just a line to let you know,LIFE IS GOOD! after installing DynaS with coils and going through the carbs more than I wanted to,the gs750 1979 is back and off life support. the vac was set with my homemade manometer but as I stated before couldn,t fine the right setting for fuel metering screws(the ones under the fuel bowl.)well I found that they are to be set at 2 1/2 to 4 turns out,with air screws around 1 1/4(factory) setting.i know it sounds like much on fuel screws but the Roadster is up and over the flu. the reason for (if you check out my other post) doing everything was trying to figure out the reason for (out of the blue ) start running like crap. I figured it was the coils going out. must have been the problem,cuz no more popping etc. anyway,thanks to all who gave info.Captrise ps Happy Bird Day to all.

 

[Gumpster]

I had a similar condition only to eventually find the tips of the fuel screws were broken and stuck in the tiny holes. Over 1.5 turns is a bunch. Any other mods? Pods or exhaust?

 

[tkent02]

Yeah, that ain't right.

 

[Steve]

With the fuel screws out that far, there is something else wrong. :-k

.

 

[tkent02]

My guess would be the broken off screw tips blocking the ports.

 

[Steve]

In which case it wouldn't matter how many turns out they are.

.

 

[tkent02]

Oh well, don't know where but cloggage someplace for sure.

 

[captrise]

Like I said before thanks to all.Steve ,Chuck and the rest,i tried to figure this one out. The last post I said everything was good, and it was ,,for about 10 miles, after the plugs began to foul do to all the extra fuel..So I went back and pulled the carbs and set the fuel screws at 1 3/4 turns out. first I went through the carbs to make sure that there wasn't any trash inside then set them. still after around 10 miles I pulled the plugs and found that they were still rich. well I pulled them again and reset at 1 1/4 out. as you said Steve fuel needle is on #3 space. air is set 1 1/4. this is really close and I think I will call it good. after a day or so break I,ll try set vac with my homemade meter. Thanks to all you guys, I cant tell you how much your input has been. Also ill put my pics up soon. im afraid to think back as to how many times ive pulled the carbs ,cleaned the carb,etc. i can do it (up and running) 1 hr. Ha,Ha Got to love the bikes. Thanks again Captrise

 

[tkent02]

Why not try 5/8 - 3/4 turn where they are supposed to be set?

 

[Steve]

... well I pulled them again and reset at 1 1/4 out. ...

Why not try 5/8 - 3/4 turn where they are supposed to be set?

Yep, the only time they need to be over 1 full turn is if you have pods and a free-flowing pipe.

I don't remember if you have posted what your intake/exhaust systems are, but if they are still stock, the 5/8 to 3/4 turn setting recommended by tkent should work just fine.

.

 

[captrise]

carbs

carbs

yes Steve, I did set them around 7/8 as you said. the bike didn't seem to have much up and go. This is when I went to 2 turns out . the bike did run better ,but as I said way too rich. After all the back and forth with these carbs, setting and cleaning, im working closer to the right setting. Again before they could have had something inside and I just missed it. I pulled the plugs thismorning and found that they are still alittle rich and I will set them as you said. Like I said , I did try this before and the bike didn't go to good. You guys know a lot more than myself and I will go ahead with this 3/4 ,7/8 . The plugs probably would have fouled out alittle ways down the road. Im real close, and will most likely be right on at this new setting. the air I will leave as is. might have just a tweek or so. This is what I have stock exhaust , stock air box ,dyna s with green coils. 102.5 mains 15 pilot. The guy that had the bike before me said that he had a jet kit installed. the bike did have K&N pods. as far as I could tell that is all. When I pulled the carbs for cleaning I noticed that 102.5 mains ,15 air so the bike was right around stock.Somebody fed him a bunch of crap. Anyway I put everything back as stock ( New kits) the began to run bad and I thought maybe a bad coil as the points were new. This is when I put in the dyna s . well ive bent your ear long enough.I will set them as you said and let you know. By the way I took it for a spin lastnight and the bike at around 55 60mph ....just wants to getup and go, like its just wanting to scream. Again thankyou so much ,Captrise

 

[Steve]

I did set them around 7/8 as you said. the bike didn't seem to have much up and go. This is when I went to 2 turns out . the bike did run better ,but as I said way too rich.

Keep in mind that the 7/8 setting is what works for most carbs, yours might be a little different.

Also keep in mind that an adjustment of just 1/8 turn makes a noticeable difference, and you changed it that 1/8 turn PLUS a full turn.
No wonder it's running rich. :-\\\

When you get the fuel screws set to wherever you think you want to run them, set the air screws (the ones on the side of the carbs) to double that as a starting point. If it is still running a bit rich, open up the air screws 1/8 to 1/4 turn and try again. Do all your adjusting at the air screws, leave the fuel screws alone.

.

 

[captrise]

carb settings

carb settings

Hello Steve, you guys got me in the right area and at 5/8 to 7/8, 3/4 etc. still left with black plugs. so 1/2 is what I have and the plugs are a color of ...lets say ice tea! the air screws are turned 1, that's it. the bike is running great,get up and go. the idle is 900. sounds real good.i hope that its not tooo lean? seems to running great. I COULD NOT HAVE DONE THIS WITHOUT YOUR INPUT. the other guys the same .thanks to you all.still going to set vac. but I heard that you must first check the valves. I did my kz 900 so this I think I can do . If you can answer this , is there a too lean setting on the gs? I mean the bike runs better than ever, just hope im not to lean and hurt the bike? the spark plugs have color so maybe alittle black isn't bad? its just with alittle black , after a few miles, the bike started running bad , so what is a man to do. maybe just getting worked up over nothing. just wanting to cover all bases. also im setting with air screws ,in richen, turn out lean out carb right. ok im gonna go. thanks Captrise

 

[Guest]

Tea is good. Actually, you could even stand to go a tad leaner. If it were me, and it's running good, I'd leave it.

 

[Steve]

Also remember that there is more than one circuit in the carb that needs "tuning". :-k

The screws you have been adjusting are the "pilot" circuit or "idle" circuit. They will control the coloring on the plugs up through about 1/4 throttle. From 1/4 to about 3/4, you will be on the "needle" circuit. From 3/4 to full, you will be on the "main". Yes, there is some overlap in these circuits. but they are easy enough to tune by doing "plug chops". Basically, you will hold the throttle at a particular setting for a while to color the plugs. Then you will "chop" the throttle, pull the clutch and hit the kill switch (all at the same time), then coast to a safe place, remove your plugs and read the colors. To check the pilot circuit, hold the throttle at about 1/8 for about a minute. You will need to be in a higher gear, going slightly uphill, if possible, as 1/8 throttle will speed you up quite nicely in the lower gears. To check the needle, you need to hold 1/2 throttle for 15-20 seconds. This will definitely need to be uphill in a higher gear (but low speeds). The main jet needs to be checked with the throttle wide open, fortunately one long pass (third gear from 20 mph and up) should give you a good indication.

Keep in mind that all of this tuning assumes that your carbs have been properly CLEANED and re-o-ringed, and the float heights are set to proper heights. If any of this has not yet happened, forget any tuning, you will just be chasing your tail.

By the way, if you want to try to lighten the color on your plugs right now, turn the air screws (the ones on the sides) out about 1/8 turn each, to see if that helps. No need to mess with the fuel screws (the ones on the bottom) any more, just do the fine-tuning with the air screws.


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[tkent02]

With the pilot circuit it doesn't hurt to be on the lean side. It's not going to burn anything up. Just tune it for the best throttle response at just barely open throttle settings. Anything other than lean is just a waste of gas. But first, adjust the valves and synch the carburetors.