82 gs650g probable carb issue.

[Boawedsmark]

I just bought a '82 650G from upstate NY (I live in Florida) and have spent a week trying to figure out what it is doing; sitting at idle at a traffic light it will idle up to 6-7000 rpm. When crusing and letting go of the throttle to shift, it will instead rev up to 6-7000 or higher, but not always. Plugs 2,3,4 are fouled after a few minutes. Pilot screws are 2+ turns from bottom, main and pilot jets are clear. I have not looked at the diaphragms, but the slider does rise when i blow in the right bore. I located and repaired at short from stator (w/g, and yellow wire). I have a clean tank, fresh fuel, correct fuel level in carb bowls.
Cone airfilters have been installed by previous owner, and they are clear. I would prefer the stock air filter assembly, but are missing some parts.
The throttle cable is routed correctly, but does rise somewhat when turning full right- still have to work on it.
The carbs are in synch (checked two days ago).
Fuel mileage is way off, empty tank after 50 miles!
It stumbles on and back fires, mostly through carb 2.
Where do I start? Why does the rpm rise?
Any help would be very appreciated.
Bo

 

[BassCliff]

Greetings and Salutations!!

Greetings and Salutations!!

Hi Mr. Bowawedsmark,

You may have several issues. Faulty petcock, air intake leaks, gummed up carbs, jetting may be wrong, etc. See the maintenance lists in your "mega-welcome". These are tried and true procedures.
I just stopped by to welcome you to the forum in my own, special way.

If there's anything you'd like to know about the Suzuki GS model bikes, and most others actually, you've come to the right place. There's a lot of knowledge and experience here in the community. Come on in and let me say "HOoooowwwDY!"....

Here is your very own magical, mystical, mythical, mind-expanding "mega-welcome". Please take notice of the "Top 10 Common Issues", the Carb Rebuild Series, and the Stator Papers. Now let me roll out the welcome mat for you...

Please click here for your mega-welcome, chock full of tips, suggestions, links to vendors, and other information. Then feel free to visit my little BikeCliff website where I've been collecting the wisdom of this generous community. Don't forget, we like pictures! Not you, your bike!

Thanks for joining us. Keep us informed.

Thank you for your indulgence,

BassCliff

 

[gustovh]

My advise for what it is worth. Pull the carbs and follow the carb cleanup instructions on this forum. Loose the pods and replace with stock airbox.
Just be sure that everything is clean and dry when you reassemble the carbs.
While they are off, replace the intake boot O rings. Be sure to use a impact driver to loosen the screws, then replace them with stainless allen head bolts.
My guess is that will fix the problem. Carbs are deffinately not set properly and therfore suspect.
V

 

[1_v8_merc]

RPM rising is usually linked to air leaks, atleast in my experiences.

I have the exact same bike as you do.
I've discovered air leaks quite a bit so far, even after tightening them!


Check your carb boots, are they flexible? If not, gonna need new ones.
(you could soak them in warm water, that may bring some life back)

Also buy new new Carb boot O-rings, they goto the Front Carb boots that stick to the motor itself.

Also buy new Carb boot Clamps, they wear and loose grip usually and it may not even look like it half of the time.(just atleast double check them)

Also get the right filter setup going again. You really needa try and get one! 99% of the time, Running issues are due to air filter modification and the person NOT tunning the bike or re-jetting afterwards or whatever they needed to do on that particular bike.

I've heard it a million times on here and other forums, people buying aftermarket and having all kinds of weird problems.
Some bikes don't mind them, others wont run worth a crap with them!

-------

It's also possible the carbs are blocked or gunked somewhere.
But if you have a clean tank, usually the good fuel will push it's way thru anything blocking, and it will eventually unblock it, unless it's a severe clog(i know others are going to argue, but whatever.)

 

[Boawedsmark]

Thanks for all info. One more notice: When I was working with the Pilot Screw for mixture, I did per instructions use a remote fuel tank and plugged the fuel cock vaccum hose that is attached to carb#2. While under idle, the plug in the vaccum hose shot out and flew 10 yards. I replugged it and it stayed for a while, but suddenly shot out again, clear across the garage.
-Is this normal? Shouldn't it be a vaccum rather than a positive pressure from the combustion chamber?

My course of action is to completely clean all carb bores, check the membranes, needle etc. Find a stock air filter assembly, I have the housing but no manifold, filter with "cage", or the cover. Does anyone have these items for sale?
Next, I will set air/fuel mix with the fuel cock in PRI to eliminate the membrane function of the fuel cock. If this turns out good, I will test in ON position to test the membrane function. This way I can pin point if the fuel cock is faulty. Right?
By the way, the bike has 11,500 miles and has been registred and ran every year, although very limited.
Bo

 

[Boawedsmark]

The rpm rise was due to wrong adjustment of: idle screw under carbs, tension of throttle sleeve at carbs, and throttle handle. The black plugs are due to cone filters; eliminating the airbox also eliminate the Blowback system (evap) in the GS motors. This system recycles the internal combustions chambers gases, and excessive fuel vapors, back in through the carburators. Cone filters, which where installed on my bike, completely messes up this system and the gases, and fuel is vented to the atmosphere. I have permanent black plugs since I can't compensate with air/fuel mix screws alone. i will find out if the hack also changed the main jets tomorrow. In the meanwhile; I Need A Stock Airbox.

 

[tkent02]

Thanks for all info. One more notice: When I was working with the Pilot Screw for mixture, I did per instructions use a remote fuel tank and plugged the fuel cock vaccum hose that is attached to carb#2. While under idle, the plug in the vaccum hose shot out and flew 10 yards. I replugged it and it stayed for a while, but suddenly shot out again, clear across the garage.
-Is this normal? Shouldn't it be a vaccum rather than a positive pressure from the combustion chamber?

Backfire.
Did you adjust the valves yet?

 

[LarryA_Texas]

cable

cable

Not to take away from all the other posts...they are correct that you probably have an air leak somewhere. But if the rpm changes when you turn the handlebars you don't have enough play in the throttle cable. That could be the 7000 rpm issue all by itself. Check again and make sure your throttle isn't opening because of the cable. There has to be some free play in the cable.