1980 GS850 L Won't stay running without starter fluid

[Guest]

Hello,
Great forum. Hope you may be able to assist. We are unable to keep it running unless we spray starter fluid into air filter box.
So my son and I bought a 1980 GS850 L for a project bike. It needed a few thing right from the start so let me list what we have done so far.

1. Inside tank was rusty. We cleaned it out with water and sand and flushed. A few rust spots remain but gas looks to be clear. The gas line from tank is in place but there are other stems on tank for hoses that are not there. Not sure if there are just vents.
2. Open nut on float body and gas comes out.
3. Pulled carb, floats working and jets clean and clear

I have been reading about this bike and it seems it’s very fussy and everything needs to be just so to run.
I believe the is all a fuel related issue. Should I flush the tank again or just replace it? What about the missing hoses on the tank? Any ideas at this point would be great.

Thanks in advance.

[chef1366]

The carbs need to come apart and cleaned.
The petcock needs checked
Check compression to see if the engine is healthy,
Obviously you have spark at the plugs but check all four to be sure.
Make sure the airbox is installed and sealed.
Change out the intake O-rings and make sure they are supple as is the air box boots.
Oh and put away the starter fluid.

[JTGS850GL]

Don't forget to do the basic maintenance like adjusting the valves along with the carb rebuild that Chef just mentioned. Tight valves will cause hard starting as well and will aggravate any carb issues as well. Remember to do a proper vacuum sync after your rebuild the carbs.

[Nessism]

Check the Newbie Mistakes thread and carb rebuild tutorial linked in my signature. Both can help you.

[Steve]

Another thing that might help is to list your location. There is a pretty decent chance that one of is is near enough to help.

.

[dadandson]

I am in Atlanta GA. This is all good info. Thanks so much. I found another thread that said this guy had a vapor lock. Put small amount of gas in each cly and it worked for him. Thoughts. I downloaded the carb rebuild guide as well. Real good stuff

[JTGS850GL]

Where in Atlanta are you? I'm in Grayson.

[dadandson]

Powder Springs. It's a little ride. Hey so I mentioned that I have other lines on the tank that were not hooked up. I watched this video just not and the 2nd line from the petcock is a vacuum line. I think that could be a smoking gun. That should work like a fuel pump right. Going to get some hose. Will check back. thanks

[Cyrano]

Hi dadandson,

I have the same bike and had the same problem. My suggestion is to try running it without the fuel tank. Hook up a bottle/funnel to the fuel pipe to the carb and blank off the vacuum hose.

The fuel tap (petcock) has the one way valve inside it, which is likely to have disintegrated. This means that the fuel is drawn through in pulses and might not be sufficient to keep it running.

[JTGS850GL]

That vacuum line is used to open the petcock. Without it connected it wont allow fuel to pass through the petcock. To test if that's your problem, you can put the petcock in the prime position and that will bypass the need for vacuum. You'll still need to plug the vacuum line. Best thing is to pick up a vacuum line since it's missing and connect it from carb #2 vacuum port to the vacuum port on the petcock. You'll still need to put in in prime to get the float bowls filled or you'll be cranking the engine for some time. Just remember to not leave it on prime with the engine off once the float bowls are filled or you may be wondering why you have gas in your oil.

Since you flushed out the tank with water, I'd let some of the gas come out of the tank into a cup. Make sure that no water is present. Water will settle to the bottom. I'd also drain anything that's currently in the float bowls since there may be some moisture or old fuel in them.

You may still end up having to rebuild the carbs. Don't forget the other maintenance stuff like valve adjustments and such. It's not optional on these bikes.

[dadandson]

OK will do. Would you have a set of directions on the valve adjustments. Ya I'm a newbie. but really, thanks again.

[JTGS850GL]

Here's a web site with a ton of information:

http://members.dslextreme.com/users/bikecliff/

Here's the link to the valve adjustment write up:

http://members.dslextreme.com/users/bikecliff/images/gs850valve_adjust.pdf

Here's a great carb rebuild tutorial:

http://www.mtsac.edu/~cliff/storage/gs/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf

and

http://www.mtsac.edu/~cliff/storage/gs/mc_maint/GS_CV_Carb_Cleaning_Series.pdf

And finally here's your factory service manual:

http://www.mtsac.edu/~cliff/storage/gs/GS850_Manual_HiRes.pdf

[eil]

Hi, I'm Charles and I have the same bike. Welcome to our humble forum.

The gas line from tank is in place but there are other stems on tank for hoses that are not there. Not sure if there are just vents.

Okay, that could be one problem. There are three hoses going to the gas tank:

1) Petcock fuel line to carbs
2) Petcock vacuum line to carbs
3) Fuel level sender drain line

It sounds like you have the fuel line hooked up but maybe not the vacuum line. This connects to a nipple somewhere on the #2 carb, I believe. When the bike is running, the vacuum pulls open a diaphragm in the petcock and lets gas flow into the carbs.

The fuel level sender drain line is just to keep gas off the engine in the event that the seal inside the sender springs a leak. Doesn't affect the running of the bike, but it's a good safety feature when you get the bike put back together.

Have you cleaned your carbs? Like, really cleaned them? By taking them apart and soaking all the parts in cleaner for 24 hours? If not, then you're wasting your time until you do. See the links that others have already posted, the carb cleaning tutorials are in there.

Be sure to check that your petcock is functioning correctly. No gas should flow out of it when there is no vacuum applied to the vacuum line. Likewise, there should never be any gas in the vacuum line. To play it safe, most of us recommend replacing the petcock with a brand new one so you never really have to worry about it.

P.S.: Throw away the starter fluid. If the bike doesn't start without it, you already know something is wrong. Better to address the root cause then to keep firing it up with the fluid and then just sitting there puzzling over it. More importantly, overuse of the starter fluid can wash the thin oil film off the cylinder walls which is bad for reasons I won't elaborate.

P.P.S.: Also, we'd sure like to see some pictures of the bike if you have 'em!

[dadandson]

OK just a followup on today work. Cyrano I tried what you said. Got a funnel and bypassed the petcock/tank. Bam! started right up. Took apart the petcock. Bad. But now I have a running bike thanks to all of you.

So next I need to get
Front brake cyl
break pads
rear break light assy
front directional assy
Ign relay
rear tire
If you have any for sale let me know..
I would also like to get the tank re-done at some point. I will read back through your posts again and apply the knowledge. Have lost of good manuals now as well. You have all made me a hero in my sons eyes.
Hope I can return the favor.

Dave

IMG_0165.jpg

[JTGS850GL]

Add a new petcock to the list since rebuilding it is not a good option. They're not that expensive and it will be good for another 30 years.

Don't forget to do the valve adjustment before you get too far along. Tight valves can damage the engine if run that way.

Carb rebuild is probably in order as well. If your repair list is that long then the carbs have most certainly been neglected. You wont believe how well it will run after you get this done and the carbs resynced.

Check your charging system and make sure it's in good working order. Many GSes have suffered from a damaged charging system and burnt/corroded electrical connectors.

Glad you're on the right track now. Now update your user profile to show what bike you have and where you're located. It will make it easier for others to help you without having to ask as many questions.