bike not running well...out of ideas! (850gl)

[scout127]

I recently bought an '83 GS850GL. The bike will barely idle (i have to work the choke/start lever to keep alive). When idling, it spits and sputters out of the carbs and exhaust. I went through the carbs (no change). I checked the timing, and it was off (not enough chain links between cam sprockets). After fixing that, it ran only slightly better. I'm not sure if it is carbs, valve timing, or electrical.

Also, i have never seen a strong spark from the plugs...there is a spark, just not as strong as I think it should be. I replaced the igniter unit with a used one from a salvage yard when it failed an igniter test (followed instruction from manual). The new/used box made little to no difference.

I'm at the end of my rope and don't know what my next step should be. Any help would be appreciated.

thanks!

 

[doctorgonzo]

Do a search for BassCliff's website. Step one is to clean your carbs (tear them totally apart and soak them in solvent kind of clean them) then replace all the internal o-rings, then you'll want to check you boots that connect your carbs to the engine and make sure they are soft and replace the o-rings they have behind them, then you'll want to check the boots that go to the airbox and make sure they are pliable, then you'll want to make sure you have a properly oiled filter in the airbox, then you'll want to check your plug wires and caps, then.... you get the idea

 

[scout127]

I have cleaned the carbs well. I am wondering if I'm getting proper vacuum to the carbs because the bike dies when I give it throttle (as if the CV carbs are not getting the vacuum they need to lift the needles). This could point to the boots (they do seem a little stiff).

Also, I should've mentioned that as of this week I haven't measured any resistance from the signal generator. I had good resistance before, but now none. The bike is not running any different since I've discovered this. I'm thinking my problem is electrical but open to any advice.

 

[Nessism]

As the Doc said, clean the carbs. Most newbies short cut the clean up process and wind up having to do it again. Tutorial here... http://www.thegsresources.com/gs_carbrebuild.htm

You will need new o-rings for the carbs and the rubber intake boots. You can get them from cycleorings.com

Good luck.

 

[80GS1000]

Might need coils if you have a weak spark. Dyna 4 ohm coils and new spark plug wires are the ticket if it does. Or your connections are dirty. How new is the battery and is it fully charged? Are you getting 12v to the coils?

Have you checked the valve clearances?

 

[scout127]

I have a new battery. How do I check the valve clearance or where can I find instruction for that? I will certainly go through the carbs again and replace the boots.

any other ideas?

 

[SqDancerLynn1]

#1 question It sounds like YOU DID NOT reinstall the air box ???
#2 Check the valve clearances
#3 Do a compression test
#4 check for 12 V at the coils
#5 time to get into the carbs
BaseCliff's site has a tutorial for valve adjustment

 

[Steve]

To check the valve clearances, follow the procedure in your manual. If you don't already have a manual, now is a good time to order one. General order of preference would be 1. Factory manual (you can download a copy from BassCliff's site), 2. Clymer and 3) Haynes. Nothing really wrong with any of them, but sometimes a procedure is explained or illustrated better in another book. (Personally, I have all three here.) There is supplemental information on BassCliff's little website, specifically in his Valve Adjustments (8-valve) page. There is a special tool called for that is used to hold the valve open while you pull the shims out. That is available from places like Z1 and sometimes on eBay for about $15. Many of us use what we call "the zip-tie method" which is much cheaper and usually easier. Another tool can be acquired in the form of an Excel spreadsheet that I have developed that will help you with the math to determine what size shims you need. E-mail me with a request. Put something about valve adjust spreadsheet in the subject line to get it past the filters.

 

[scout127]

#1 question It sounds like YOU DID NOT reinstall the air box ???
#2 Check the valve clearances
#3 Do a compression test
#4 check for 12 V at the coils
#5 time to get into the carbs
BaseCliff's site has a tutorial for valve adjustment

Yes. I am generally trying it WITHOUT the airbox. however, when I have put the airbox on the bike, it doesn't run much better. It still spits and sputters into the box and won't rev anymore than without it. My compression is just above 100 (my manual says that 100 is the minimum) on all four cylinders.

 

[scout127]

To check the valve clearances, follow the procedure in your manual. If you don't already have a manual, now is a good time to order one. General order of preference would be 1. Factory manual (you can download a copy from BassCliff's site), 2. Clymer and 3) Haynes.

Thanks. BassCliff's site was helpful. I downloaded a manual. I also have the Clymer manual. I'll try to do a valve adjustment. The "zip-tie method" seems just fine with me.

 

[Nessism]

An engine what won't run without choke is a classic example of plugged pilot jets. I know you said you cleaned the carbs but did you remove the pilot jets and hold them up to a light to make sure the orifice is open?

 

[doctorgonzo]

Yes. I am generally trying it WITHOUT the airbox. however, when I have put the airbox on the bike, it doesn't run much better. It still spits and sputters into the box and won't rev anymore than without it. My compression is just above 100 (my manual says that 100 is the minimum) on all four cylinders.

That's little concerning (the compression) but since the bike won't run it's cold compressions so odds are you are ok.

 

[BassCliff]

Greetings and Salutations!

Greetings and Salutations!

Hi Mr. scout127,

I'm glad you've found us. As Mr. Steve mentioned, you'll find lots of GS850G lovin' on my website. Let me play the welcome wagon for a moment...

Please click here for your mega-welcome, chock full of tips, suggestions, and 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. Thanks for joining us.

There is a general procedure that must be performed that establishes a baseline for further troubleshooting. Our dear beloved Mr. bwringer described it best (you'll find this in the mega-welcome):

***********Quoted from Mr. bwringer************
Every GS850 [and most other models] has (or had) a set of well-known issues that MUST be addressed before you have a solid baseline for further troubleshooting. It's a vintage bike, and it's quite common (as in, every single GS850 I have had contact with) that there are multiple problems that have crept up and slowly gotten worse over the years. It's not like a newer vehicle, where there's generally one problem at a time.

These common issues are:

1. Intake O-rings (install NEW OEM or Viton only - common nitrile O-rings will quickly deteriorate from heat)
2. Intake Boots (install NEW -- these cannot be repaired)
3. Valve clearances (more important than most people think)
4. Carb/airbox boots
5. Airbox sealing
6. Air filter sealing
7. Petcock (install a NEW one)
8. On '79 models, install new points or Dyna electronic ignition (or at least verify that the old points are working correctly)
9. On all models, it's fairly common to have problems with the spark plug caps. These are $3 or $4 each, and often worth replacing if you're keeping the stock coils/wires.
10. Stock exhaust with NO leaks or holes -- good seals at the head and at the junctions underneath.
**********[End Quote]*******************


The 850 is particularly sensitive to air intake leaks and will run badly, if at all, if the airbox is removed. On my website you'll find a pictorial guide from Mr. Roostabunny describing how he sealed up his airbox. It's also important to check and clean every electrical connection on the entire wiring harness (you'll find tips in the "Odd and Ends/Electrical" section). Run a dedicated ground wire from the regulator/rectifier to the negative terminal of your battery. Keep us informed.



Thank you for your indulgence,


BassCliff

 

[scout127]

An engine what won't run without choke is a classic example of plugged pilot jets. I know you said you cleaned the carbs but did you remove the pilot jets and hold them up to a light to make sure the orifice is open?

I replaced the pilot jets because their heads were chipped (apparently someone didn't use the correct flathead). I can sometimes get the bike to idle, but it will not rev. when i give it throttle, the rpms drop and the bike dies.

 

[scout127]

Thanks for the welcome.

Thanks for the welcome.

I'm glad to be here. I've already received some great advice and hope it proves to be useful. I'm at my wits end with this bike, but I think I have some good leads.

Your website was helpful. I downloaded a manual and a cv carb cleaning guide. Thanks for the help. I'll be back for more!

 

[Steve]

Just out of curiosity, what part of Mississippi? :-k

Just wondering how close I was to you a couple of months ago when I was in Greenville.

Oh, you can try running the engine without the airbox if you fold a shop rag in half, drape it over the carb inlets and clamp it to the outer carbs with zip ties. It works well enough for a ride around the block, but it's not accurate enough to do jetting checks.

.

 

[scout127]

Just out of curiosity, what part of Mississippi? :-k

Just wondering how close I was to you a couple of months ago when I was in Greenville.

Oh, you can try running the engine without the airbox if you fold a shop rag in half, drape it over the carb inlets and clamp it to the outer carbs with zip ties. It works well enough for a ride around the block, but it's not accurate enough to do jetting checks.

.

I'm in Clinton...just west of Jackson.

I have been wondering how much the airbox would affect the carbs. I'm guessing that the diaphrams will not work properly without the airbox.

 

[Steve]

I'm in Clinton...just west of Jackson.

I have been wondering how much the airbox would affect the carbs. I'm guessing that the diaphrams will not work properly without the airbox.

Correct on your guess. There needs to be some restriction ahead of the carbs. Either a stock airbox or pods will work, but a folded shop rag works, too. This restriction adds to the vacuum caused by the air squeezing under the diaphragm slide, and it is this vacuum that lifts the slides.

.

 

[jed.only]

sounds like the AF is uber-lean. the choke is masking this lean condition and giving you grey/black plug chops. If the bike runs better with the choke on, you can bet it is too lean.

 

[scout127]

sounds like the AF is uber-lean. the choke is masking this lean condition and giving you grey/black plug chops. If the bike runs better with the choke on, you can bet it is too lean.

I think you're right, but I haven't gotten the bike to idle well enough to adjust anything yet.

I'm also wondering if the bike dies when I open the throttle because it receives a ton of air but no fuel (because the needles are not lifting very well) this would also mimic a lean mixture...right?

Would any of this cause the bike to spit and sputter from the carbs? Just checking because this backfire makes me wonder if I have a timing issue (though I have checked and double checked the timing), or an electrical issue.