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Carb settings for 80 g850

  • Thread starter Thread starter mattydefran
  • Start date Start date
M

mattydefran

Guest
Hello,

I just started working on that 1980 gs850 I picked up. It was sold in not running condition. I figured maybe just a carb cleaning or something. WRONG!!!!!!

I took the carbs off and cleaned them really well. All the jets were clear but there was a ton of rust sediment in the bowls. I put the carbs back on and tried to maually feed the gas to them with a squirt bottle connected to the main fuel line into the carbs. I get a couple of pops every now and then as I am cranking it over, but no fire as of yet.

I am afraid that the yahoo that had it before me played with the adjustments on the carbs. I found the mixture screws all out of wack. ranging from 3.5 turns out to 7.5 turns out. I set them to 4 turns out accross the board. This is the basic setting for my Bandit, just a shot in the dark figured I would try it.

Can someone give me the basic settings for the carbs on this bike just to get me close. Like mixture screws, maybe idle screw, anything that you think might be causing the bike not to run. I checked spark at the plugs and it seems fine.

Anything anyone could offer would be greatly appreciated I am lost at this point and I have killed my battery. I have it on charge for tonight plus I have a spare for tomorrow.

Thanks
 
I'm not sure 1 1/2 is enough. My 850 was box stock and all the pilot mixture screws were 2 1/2 turns out from the bottom.
 
About two turns out (stock intake) is ballpark for the mixture screws. That may not be exactly right but it won't be the reason it won't start.
Check some basics since they should be checked anyway.
First of all, make sure any temporary fuel container is properly vented. Before you try to start the bike, prime it to be sure the bowls are completely full. One odd footnote in the factory manual says "1980" petcocks must be primed by cranking the motor...not just turning the petcock with a screwdriver to prime and letting gravity fill the bowls.
There's been discussion here before about these petcocks and this special prime thing, but I'm just saying it's in the factory manual and applies to '80 petcocks only. It's possible there's not enough fuel in the bowls and a low fuel level will obviously make it not start.
Be sure the vacuum line is connected to #2 carb and is in good condition and not kinked.
Be sure any float bowl vent lines are clear, not kinked and routed under the seat.
Be sure the air filter is clean and all airbox seals are good.
Check out the CV carb section and do the best bench synch you can. If the throttle valves are not synched at least reasonably or they're sticking from non-use, the bike won't start.
Tighten the clamps on both sides of the carbs correctly.
Turn up the idle adjuster knob enough so the bike will start.
Check spark plug gaps.
Do a static check to be sure the ignition is timed right. Once running, check timing and the advancer action with a gun.
 
Got it running whoo hooo. combination of crappy spark plugs, and a few bad grounds. Seems as though The last guy rewired a few things and grounded things in all different directions probably saving money on wire [-X

Anyway now shes running but we found a new problem it idles nice, revs up nice until it hits about 5,000 rpm then she bogs out. Opening the choke will let the rpm's go up a little more, but does not solve the problem. I didn't have the airbox on at the time so I am going to try that to see if it might clear up.
in the meantime anyone have suggestions.

Thanks
 
You must have the airbox on and properly sealed as Keith has said. I am surprised you got it running as much as you did without the airbox on.
 
dpep said:
You must have the airbox on and properly sealed as Keith has said. I am surprised you got it running as much as you did without the airbox on.
Click to expand...

I tend to disagree. Yes not having the airbox on will cause the bike to run rough. But as far as a motor not running at all because of an airbox not being attached. Any motor will idle and run without the airbox or airfilter attached. unless of course in the situation with a car where there is is a MAF sensor attached to the airfilter box yes that will cause a motor to die out. Because the Maf is connected to the ECU which controls fuel and everything else. But as far as motorcycles go you can run them all day without a airbox attached. Again they will not run correctly but they will still run. In Fact a guy I work with got a 81 yamaha maxim 750 for free from a guy. the bike had a broken air box he said the hell with it and runs the bike with no air box or filters. he rode it all summer that way. Of course it is not a smart Idea because of the dirt and contaminents that can get in and clog up the carbs and hurt the motor, but he says screw it the bike was free.

I am not trying to be a jerk I am just trying to save a little newbie face :oops: . This might be my first GS, but not my first bike, and definately not the first motor I have worked on.
 
The airbox seal check was just one of many basic checks I listed.
In the case of a bike in "not running condition", I always try to mention several things because the problem may be an accumulation of things. Dirty carbs, some corrosion on electrical connections, too wide of gap on the plugs, etc, all these things can add up to a no start condition.
So nobody said the bike won't run with the airbox off or with poor sealing. But it will have a negative effect and in combination with other things not right, you can have a no start condition.
 
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