Throttle issues

[Beef]

Hi, new owner here trying to work out some kinks. I bought the bike in Oct and just took delivery of it yesterday, bought it off of a aquintance. Well it is a 80 GS750E with 17k with an after market exhaust.

When I bought it my buddy said he cleaned the tank out and also cleaned up the carbs a bit, he also said that I needed a new petcock since the old one seemed to be starving the bike @ higher RPM. So I left the bike with him to replace it before I picked it up... well 2 months later and nothing so I just picked it up not talkin to the guy since he was out of town.

I got the bike with the tank and a couple of other things not attached properly so last night I went ahead and but everything back together except for the rear air box that holds the filter. Well i read the owners manual on how to start it in the cold and sure enough it fired up just fine after the gas got flowing using the choke. Once I had it running for about a good 2 mins I pushed the choke in and it died, then I again started the bike using the throttle. It then spit and popped and it seemed like the carbs were dead after 3k RPM couldnt go any higher. I also just tried to use the cable adjustment to get her to idle right and still no dice idling.

So I have a wicked dead spot @ 3k and the bike will not run lower than 1.5k. Also when I bought the bike it was running fine no dead spots and would idle fine but you could hear it start to break up up top under load and that is why my buddy said it needed a petcock. Oh and the bike has been sitting for 2 months untouched

So any insight would be great peeps,

TIA

[Beef]

Well just pulled the plugs

#1 looks lean
#2 looks like it is black and charred
#3 is wet
#4 is wetter


Getting spark outta all 4 cyls

[chef1366]

You can't run the bike without the airbox on. It will run lean.
Do you have the petcock with the slot or the lever?
Here's a link for the 80 slotted petcock from ebay.

http://cgi.ebay.com/ebaymotors/1980-GS550-GS750-GS850-GS1000-GS1100-PETCOCK_W0QQitemZ180062217298QQihZ008QQcategoryZ35597QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

[Beef]

I have the slot type, but I still have the front box on and i have seen it run well with only the front box attached.

Thanks for the reply

[Pearson]

I have the slot type, but I still have the front box on and i have seen it run well with only the front box attached.

Thanks for the reply

What's a front box? For starters I'd get that airbox back on the bike. I've run mine without and it ran ok but putting the box back on and making sure all my hoses were routed to the right places made all the difference. Might consider just replacing those plugs, they're readily available and cheap. When I was just starting out working on the bike in May I was chasing all kinds of demons that disappeared with a new set of plugs.

[Beef]

What's a front box? For starters I'd get that airbox back on the bike. I've run mine without and it ran ok but putting the box back on and making sure all my hoses were routed to the right places made all the difference. Might consider just replacing those plugs, they're readily available and cheap. When I was just starting out working on the bike in May I was chasing all kinds of demons that disappeared with a new set of plugs.

Well when I say front box I mean the box that the carbs attach to that funnels down to a 3" hole then the other airbox attaches which holds the filter under the seat.

I will pick up another set of plugs eventhough these look new. I am thinking that the prev owner never jetted the carbs when he put the aftermarket exhaust on so I am thinking of goin with the stage 3 kit because I have also got the K/N Air Pods as well

[Dave8338]

Well when I say front box I mean the box that the carbs attach to that funnels down to a 3" hole then the other airbox attaches which holds the filter under the seat.

I will pick up another set of plugs eventhough these look new. I am thinking that the prev owner never jetted the carbs when he put the aftermarket exhaust on so I am thinking of goin with the stage 3 kit because I have also got the K/N Air Pods as well

I'd go with the stage three kit and the pods otherwise, you'll be looking into stock exhaust and stock airbox/filter combo. You'll never get it to run right without the stock airbox/filter setup, no re-jet for pipes and after market exhaust. Pick one (all stock or pipes/pods/and re-jet).

[Dink]

Why not get a single K&N "pod" style air filter and fit it in replacement of the "rear" filter housing??
You say one plug is black and sooty and the rest look lean, this is a classic syptom of a leaking fuel valve diaphram, you can get a kit and rebuild it, or just replace it.
I would pull the carbs and go through them, make certain they are spotlessly clean (i.e. my mate cleaned them a bit, aint good enough) pay particular attention to the idle circuit & especially the idle progression holes.

Dink

BTW a K&N ru-0820 is the perfect replacement "pod"

[Beef]

I'd go with the stage three kit and the pods otherwise, you'll be looking into stock exhaust and stock airbox/filter combo. You'll never get it to run right without the stock airbox/filter setup, no re-jet for pipes and after market exhaust. Pick one (all stock or pipes/pods/and re-jet).

Yeah I have been thinking the same....

New update:

Looking over the bike I decided to pull apart the carbs using that niffty guide with pix loked in the Writeups section. I have also come to the conclusion that the guy i bought this thing from never really torn the carbs all the way down so I am goint to buy the rebuilt kit along with the jet kit.

How much work is involed with rejetting the carbs using the Stage 3 kit?? and what are you guys sing to sync you carbs?? My book calls for a suzuki SST but I would like to see what you guys are doin.

Also are you guys drilling out the mettal to get to the air adjustment screws on the CV carbs??

[Beef]

Why not get a single K&N "pod" style air filter and fit it in replacement of the "rear" filter housing??
You say one plug is black and sooty and the rest look lean, this is a classic syptom of a leaking fuel valve diaphram, you can get a kit and rebuild it, or just replace it.
I would pull the carbs and go through them, make certain they are spotlessly clean (i.e. my mate cleaned them a bit, aint good enough) pay particular attention to the idle circuit & especially the idle progression holes.

Dink

BTW a K&N ru-0820 is the perfect replacement "pod"

I already bought the k/n 4 pod kit for it on ebay for real cheap. Also when you say Diaphram kit you are talking about the petcock right??


BTW found out that it is a L not a E

Is the Full Gravity fed petcocks worth the price??

[Dink]

Yes we do just drill them out, BUT VERY VERY carefully!!! the adjustment screw is just below them, if you punch the drill bit through to hard or far you will damage the screws.

Dink