Running rich, One carb leeking, Jets too big?

[Co0kieduster]

Hi all, I'm a new 1980 GS750L owner!

I bought this bike knowing it wasn't running right hoping to restore it to good condition and make it into a little cafe racer. I have very little experience with bikes (only owned a 97 Honda VT1000 before) and have never worked on carbs. I am pretty good with cars so im sure much of that experience will translate.

I have been reading, researching and asking friends for advice. I initially just cleaned the carbs (they were pretty gunked up, PO ran really old gas through them when he tried to show me that it still ran....ugh clearly he hadn't winterized the bike).

After a cleaning and not touching any adjustments I got the bike running. The carb just to the right of the fuel line started leaking fuel after a few minutes idling. While riding, without the cheap (I'm guessing Emgo or whatever it is) pod filters on, that carb seemed to leak less sometimes not at all. At first I thought it was the float needles or o rings, so those were checked/cleaned again, new o-rings and the floats adjusted to 22.5mm. still leaks.

The bike also bogs really bad....I mean really bad. Right now I guessing it's running rich. Ill pull the plugs (just put new ones in when I cleaned carbs). I also noticed that the main jets are two different sizes 140 and 137.5. Seems way too big to me. stock is 112.5. The exhaust is stock and the only change from stock is the pods.

I will also be setting the valve lash after work today (assuming this is as easy as it is on a car...a few wrenches and some feeler gauges).

I have a book for it (equivalent of a haynes manual for a car, not home forgot the name).

Anyway, my question, sorry I'm long winded, is what would you suggest regarding the leak, oversized jets, possible rich condition and bogging?

I'd like to come up with a good plan of attack. Again my goals are cafe racer style, I'm keeping the pods <--may upgrade to nicer, and maybe a freer exhaust but that wont be for a while.

 

[tom203]

More pod fun ! Pods require bigger mains, but how big?
Siiting on bike, we refer to extreme left carb as #1, etc. So your #3 is leaking ? it's either wrong float height, or worn out fuel needle seat, or nonfloating float (unlikely)
Of course it bogs, the pods and the stock mikuni carb parts can't relate to each other well. If you want to stay with pods, get some good pods ($$$) and invest in dynojet kit (more $$) to get a decent midrange.

The valve clearance check is vital- don't procrastinate- clearance is set at .001 to .003 inch (yes ,that is one thousand of an inch). It's more challenging than cars.You probably don't have gauges this small and you'll likely need a cam cover gasket.

Edit. put your bike/model year in your signature; Also, consider posting your location- might be a member here down the street! Oh yeah, welcome

 

[eil]

Sounds like you're off to a good start. Some selected responses:

I also noticed that the main jets are two different sizes 140 and 137.5.

No, the mismatched mains don't sound right.

I will also be setting the valve lash after work today (assuming this is as easy as it is on a car...a few wrenches and some feeler gauges).

Yep, it is. See this: http://members.dslextreme.com/users/bikecliff/images/16valve_adjustment.pdf

The valve clearance check is vital- don't procrastinate- clearance is set at .001 to .003 inch (yes ,that is one thousand of an inch).

On a 16-valve 750 it is not! The factory service manual says 0.09mm-0.13mm (0.004-0.005 inches).

I have a book for it (equivalent of a haynes manual for a car, not home forgot the name).

That's a good book, but it's not the best. The best is the Suzuki factory service manual, which can be acquired for free right here: http://www.mtsac.edu/~cliff/storage/gs/GS750_16valve.pdf

Our official GSR greeter, BassCliff, has been somewhat scarce as of late, but here's his Mega Welcome, a starting point to everything you need to know about maintaining these old beasts: http://www.thegsresources.com/_forum/showpost.php?p=1689496&postcount=1

 

[Steve]

Actually, the mis-matched mains were an effort by Suzuki to keep the inner cylinders running a bit cooler. I have only seen it on the '83-and-up 550 and the 1150, so this might have been an owner's attempt to do the same thing. As long as the larger jets are on the inner carbs, it won't be all that bad.

.

 

[Co0kieduster]

Thanks, for all the good info, I've been to busy to work on the bike hopefully getting a chance today.

A few things I didn't mention before.

1. The pilot jets had no plugs so i've ordered those <----maybe this will solve some of the running rich issue and bogging

2. The bogging happens before 5000rpms. like it takes ten years to get to 5 grand then it pulls like a motherf*****. If I did my hw right that should mean my mains might be ok and the bogging is due to the needles, pilot or float adjustment.

3. Not sure if the charging system is working right only getting about 12.54v at 4000rpms on a new battery.

 

[JTGS850GL]

Charging system is not working right.

The missing plugs on the pilot jets will cause you MUCH problems. Running rich for sure.

 

[Co0kieduster]

Well, I just finished the valve adjustment. They weren't too bad. All are set to .005" now.

Pulled the plugs and I was wrong they are lean clean and chalky. Going to run a compression test tomorrow then start looking into why im so lean.

Im wondering if, because the plugs are missing on the pilot jets and the mains are so big, with all those large orifices the carb is have trouble developing enough pressure to pull the gas up. I could be blowing smoke here but that is whats going through my mind. Someone with a better understanding of how carbs work can maybe enlighten me.

pilots are 42.5

 

[Co0kieduster]

Compression test was good

140
140
140
150

Got the pilot hole plugs installed took a bit to get her to idle right then took a spin around the neighborhood at 1/8 - 1/4 throttle, plugs were still lean. So I pulled the needles out of the slides and shimmed them by moving the plastic washer to the other side of the littl c clip. Bike runs really good now. Going to do plug chops for each throttle position once I get the charging system sorted.