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1980 GS850g starting trouble

  • Thread starter Thread starter dcombee
  • Start date Start date
D

dcombee

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Ok here it is. i have a GS850g 1980. I rebuilt the carbs with a carb kit. Replaced the coils with gsx coils, new wires and new caps. The bike has great spark. It just starts hard; many times not at all. I have to give it starting fluid, hoping it will start. one it does it is still slugish but after it has run for a couple munites it seems to run fine. It does hesitate a little. I am going to pull the intake boots and make sure that the o-rings are not cracked. I Could use a good starting point for setting the idle screws. Any help on how to get this thing starting right would be greatly appreciated.
Derek
 
Being a 1980 model, you can be sure enough the intake "O" rings are cracked and worthless to order them before even bothering to look at them. Theyre toast. Theyre only about a buck each.

Earl

dcombee said:
Ok here it is. i have a GS850g 1980. I rebuilt the carbs with a carb kit. Replaced the coils with gsx coils, new wires and new caps. The bike has great spark. It just starts hard; many times not at all. I have to give it starting fluid, hoping it will start. one it does it is still slugish but after it has run for a couple munites it seems to run fine. It does hesitate a little. I am going to pull the intake boots and make sure that the o-rings are not cracked. I Could use a good starting point for setting the idle screws. Any help on how to get this thing starting right would be greatly appreciated.
Derek
Click to expand...
 
It also sounds as if the air/fuel mixture isn't set up right. If you dont have your own carb-synching device, then I would suggest riding over to a mechanic. If you call ahead, they should be able to do it while you wait ....maybe an hour, if that.

Also, check your idle-adjustment knob on the bottom of the carbs. that will take some adjusting. sometimes, I have had to change it during the rides once it gets really hot, because it idles differently, but then not enough once its been shut off for a while.


Poot
 
Not counting setup, if the mech is any good at all, he can do a synch in less than 5 minutes.

Earl


Poot said:
It also sounds as if the air/fuel mixture isn't set up right. If you dont have your own carb-synching device, then I would suggest riding over to a mechanic. If you call ahead, they should be able to do it while you wait ....maybe an hour, if that.
Click to expand...
 
A little info

A little info

ok, I pulled off my intake boots today and the o-rings are not cracked but thay are hard. I'm going to replace them. I am going to get the carbs synched but shouldn't it start up anyways. I'm thinking the the Idle screws ( thats what I call them) are not set right. If anyone could give me a good starting point to set them that would be great. Any info will help. I got to say it starts to get frustrating when your bike will not start. thanks
 
Sounds starved for air, not fuel. Is your air filter plugged? - try cleaning it to see if it makes a difference.

What do your plugs look like after the bike has run a while? Are they black/sooty, wet, dry? Plugs reads give the other users more to go on.
 
I took the filter out and cleaned it, but that might not have been enough. If I take the air filter out but leave the air box on would I be able to see if it is getting enough air. I also heard that there is a way to bench synch the carbs, at least to get it running so that they can then be done with synchronizer, could someone tell me the best way to that. Also while I have the carbs off I thaught I would check the bowl floats one more time. I would like to make sure that I set them right so if somene could give me the way they set them and also at what hight that would be great. thanks, Derek
 
You should be able to start the engine without the air filter, but this will be running lean. The mixture screws you are talking about are on the engine side of the carbs so they shoudl be fuel mixture. A good starting point is about 1.5 to 2 turns out, but may be as much as 3.5 turns. If you used a rebuild kit did you get the right size jets? Do yo have a stock air box and 4 into 2 exhaust? Did it run before the car rebuild?

The 1980 GS 850 is very particular about the air it gets. The type of exhaust and the type of air filter all contribute to how much air it gets.

When you rebuilt the carbs did you dip them? or just replace some parts? Did you replace all teh O rings? This usually needs to be done.
 
Yes, the CV carbs are very sensitive to the amount of vacuum in the intake system. I would clean/oil the filter really well and put it back together for testing.

The only bench synching I know of is looking at the butterfly valves inside the carb throat and making sure they all open at exactly the same time. If you do this, the engine should run well enough until you can arrange for a true 4-carb synch.
 
I took apart replaced all the parts with the ones in the kit. Replaced all the orings and the jets are the same size as the ones i took out. The bike ran befor e I rebuilt the carbs, but very poorley and it still had the starting problem. It runs fine onec warmed up but trying to start it is tuff. If it is run it will start again but only if it is not allowed to get cold. everything on the bike is stock, air box, exhaust, ect. I am replacing the orings on the intake boots right now, they were very hard and brittle. I think that they may have been leaking. I have a fealing that it is the mixture screws on the top of the carbs. Once I get them back on the bike I think I will try to mess with them a little, maybe starting at 2 turns and working my way out. Thanks
 
Ok, got the bike back together, would not start. Checked spark ( just for kicks) it was strong. Checke the plugs and they were dry, not wet so its not flooding. I know the carbs are good though so I decided to pull the petcock. It seems the the long filter tube is clogged and not any good. This bike sat for a long time and on that filter tube when held up to the light all except for the very top of the mesh seemed to be clogged up with shelack. This makes sence to me since the carbs were aso full of shelack from old gass. I removed the filter tube and am going to run an inline and hope that this helps. We shall see tomarrow.
 
If it runs at all, it is getting gas. If it starts and runs fine once it has been running and is warm but refusing to start when cold your choke tubes and or bowls are still plugged, that is if your using the choke and it's actually moving the choke assemblies. I've went through 6 1980 850's and I set all the airscrews at 1.5 turns out and all started instantly. The kits you installed are inferior to factory parts and you should have cleaned and reused all the original parts rather than the crappy kits. Did you seperate the carbs when cleaning them?
 
Just another point, may or may not be helpful. After I got my 850 back together all together after carbs, O-rings, cam chain tensioner etc. it wouldn't start. The problem was that the throttle wasn't set right and was holding the carbs too far open for the choke to work. Once I had the throttle cable set right, it fired right up when chocked.
 
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1. Make sure the levers are actuating on the carbs when you pull the handlebar choke lever.
2. Don't touch the throttle when you start the bike. Doing this bypasses the choke circuit.
3. Have a fully charged battery and make sure the voltage doesn't drop excessively when you hit the starter.

If it doesn't start after cranking a while, pull your plugs and have a look. If they are dry - you probably aren't getting fuel to your cylinders - something is plugged up. If wet, it's likely a timing or ignition problem.
 
well your right, guess I was just getting frustrated. i do think the somewhat clogged petcock filter has something to do with the slight hesitation.The plugs are dry, I know the problem is that it is not gettting gas. I set my screws to 1 1/2 turns and still nothing. I did not separate the carbs when I cleaned them. what is clogged that would keep it from getting gas on start up. thanks
 
I would first verify there is fuel in the float bowls. This eliminates a problem upstream of your carbs. You should be able to remove the bolt at the bottom of one of the carbs and let the gas run out. Should be around 1-2 ounces.

If there's adequate gas in the float bowls, then you are looking at plugged circuits in your carbs or somehow the carbs were put together incorrectly. The mention of 'shelack' is disturbing - it's old gas that has solidified and settled in the circuits. To be honest, I think you will need to break down the carbs individually and really clean them out. Carb cleaner and compressed air work wonders.
 
dcombee said:
well your right, guess I was just getting frustrated. i do think the somewhat clogged petcock filter has something to do with the slight hesitation.The plugs are dry, I know the problem is that it is not gettting gas. I set my screws to 1 1/2 turns and still nothing. I did not separate the carbs when I cleaned them. what is clogged that would keep it from getting gas on start up. thanks
Click to expand...

Yes, you are having a fuel starvation problem which you are going to fix it sounds like but also, The carbs need to be seperated to clean the choke circuit. Cleaning them without seperating them will usually ruin any O Ring that you have not removed yet. You need to pull the choke assembly out of each carb body and make sure you can blow cleaner thru the choke assembly and come out of the brass tube that hangs down from the carb body. That brass tube goes into a cavity in the float bowl, you need to be able to blow cleaner thru that hole where the brass tube lives and have it come out inside the bowl where it usually enters the cavity. If this cavity is clean the cleaner will come out with force, protect your eyes. If these are not clean and free flowing the choke circuit will not work. Another reason to seperate the carbs is that all conecting T's that have a replaceable O Ring should have them replaced along with float valve O Rings. Do a search for cycle O rings here, Robert Barr sells a complete kit of O rings for a pittance and you will need it. Another thing to check, that most people miss is the needle jet. When you remove the main jet notice the washer which sits under there. Remove the washer, insert a screw that fits the threads and tap it to remove it. Note the aligning pin, it will only go back in one way. There are little holes in the needle jet, make sure they are clean. When you assemble everything, back the idle screw out till it no longer moves the throttle assembly then slowly screw it back in till you feel resistance and notice the throttle assemble starting to move again. You just need to move it a little so it will start, then adjust it more precisely once it's running. Like previously mentioned, for a cold start up, pull choke fully, do not turn the throttle any amount at all, and hit the starter, it should fire up if you have gas in the bowls. To check your petcock, point the fuel lever straight down and hook a line to the vacuum port on the petcock, ( the smaller fitting) and carefully suck on the hose, if you can't create a vacuum and have it hold to your tongue the petcock needs replaced, If you get gas thru that vacuum line the petcock needs replaced. If your checking the petcock and it's hooked to the carbs, remove the drain screws one at a time and you should gas from all of them. Keep us informed of your progress.
 
These pics should help. Sorry they are so big. If any one of the ports pictured is not perfectly clean, it will effect the performance of the carbs.

carb3.jpg


carb2.jpg
 
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BOb, thanks for the info and pics, I will will hopefuly have time to pull the carbs and get started on taking them apart today. thanks again, I will let you know what happens. Derek
 
dipping them in berryman's, the gallon can, is a great way to really get it all out of there, but contact robert barr for sure before you do this, as you will inevitably break an oring in the dissassembly.

good luck
 
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