82 GS850L carb and ignition problem

[GSOH]

I've been using the search function on the board a good deal over the last several months, either researching bikes to buy or like now, trying to learn how to turn a wrench on my 'new' bike. That being said, I apologize in advance if this is in the wrong category...

Bike is a '82 GS1100GL body/electrical with an '81 850L engine. When I bought it, it basically needed new intake boots as it would stall and often die at idle. Various updates were done to the bike including cleaning carbs/bench sync and some electrical clean up. Since bringing it home I've done the electrolysis/tank seal using Caswell, pulled carbs and cleaned everything, installed new intake boots and intake o-rings and reassembled (with stainless allen heads ).

Bike started fine after putting everything back together, though around 3,500 rpm, bike would sputter hard and rpm would die with backfire. Pulled plugs to see whats going on there. All 3 plugs, minus cyl 3, were black. 3 was bone dry.

Last night I checked plug boots and had various readings ((0/4.95/4.63/9.86 ohms (cylinders 1--> 4)). Bought new NGK plug boots today and installed with dielectric grease. All read around 5 ohms as they are apparently supposed to read (4.78 to 5.3). Used auxiliary fuel tank (as I've been doing all the while) to start bike. So now, it wont start at all & appears to be backfiring out of no 4 cylinder (small puff of smoke when trying to start on top/near carb) & a few pops out the exhaust. It just keeps getting better .

Here is what the bike sounded like before I changed the plug boots. Noticed the sputter around 3,500 rpm. Now, it wont even start at all...

https://www.youtube.com/watch?v=7Dh0JHGUeME&feature=youtube_gdata_player

Any thoughts or suggestions? I will admit, I'm no ace mechanic, but I can get around with a wrench here and there when required and am not scared to take on a project (obviously, I just bought a 30 year old bike!).

[tom203]

Those spark plug boots or caps are 5000 ohms or 5k to some. So you followed the carb cleaning tutorial- the 24 hr dip,etc ??? Did you check valve clearances ? That's also a good time to doublecheck cam to crank timing to be safe.
Stock airbox? stock exhaust? did you notice and reinstall that little black plug near main jet cavity in each carb?

[GSOH]

Those spark plug boots or caps are 5000 ohms or 5k to some. So you followed the carb cleaning tutorial- the 24 hr dip,etc ??? Did you check valve clearances ? That's also a good time to doublecheck cam to crank timing to be safe.
Stock airbox? stock exhaust? did you notice and reinstall that little black plug near main jet cavity in each carb?

I'm 99% sure the black plugs were reinstalled. The bike was gone over fairly well from the previous owner (old_skool on here) and from what I was told all of that was done. stock airbox which was sealed and oiled. Stock exhaust. 5k ohms sounds better. whoops...

I'm starting to wonder if the coil wires somehow got switched around. I was looking on this thread and it seems like could be the case, though I have no idea how the bike would have ran the way it has up til last night if they were switched : http://www.thegsresources.com/_forum...d.php?t=208268

Plugs were switched around (operator error...?) and bike now fires right up. Maybe my garage isn't vented well enough and all these fumes are getting to me

[GSOH]

I got the bike up and running and rode in to work today (finally!). After a few minutes of riding I noticed some popping sounds in 1st and 2nd around 3-4k rpm. The idle was set around 1,300 but it keeps dipping down to where the bike wants to stall (and does). Also noticed when I started it after sitting on kickstand all day, it fired right up (no choke) and revved around 2,700rpm. I'm wondering if I need to adjust idle screws again. Right now they are all around 2.25 turns out. Too rich maybe? I did pull plugs all 3/4 were sooty black and #2 cylinder was not at all (it was sorta wet, but not saturated).

Any ideas?

[BassCliff]

Hi,

Faulty/leaking petcock? Over-oiled air filter? Weak spark? What's the voltage at the coils?


Thank you for your indulgence,

BassCliff

[GSOH]

Thanks for replying to my post BassCliff! I'm a fellow bassist currently rocking a Modulus Quantum 5. Love it to death!

I have replaced the petcock, which is/was a Drag Specialties 3/8"NPT aftermarket. The spring washer was bad and causing it to leak. Replacing the washer and back to no leaks. The inline fuel filter I installed is catching some remaining tank rust after sealing it, which I'm thrilled I installed. So, at least that part is eliminated.

I will have to check the air-filter, as I have not pulled it out of the box. I was told when I purchased the bike it was sealed and oiled.

There are no stupid questions right....so what is the best way to test coil voltage? From what I read, there is a primary and secondary. I do have a multimeter on hand.

As for the plugs, I installed new boots which seemed to help even things out. I pulled them after a post-work ride yesterday and all four were fouled with black soot. So, at least #2 is doing something.

Hi,

Faulty/leaking petcock? Over-oiled air filter? Weak spark? What's the voltage at the coils?


Thank you for your indulgence,

BassCliff

[Dave8338]

Thanks for replying to my post BassCliff! I'm a fellow bassist currently rocking a Modulus Quantum 5. Love it to death!

I have replaced the petcock, which is/was a Drag Specialties 3/8"NPT aftermarket. The spring washer was bad and causing it to leak. Replacing the washer and back to no leaks. The inline fuel filter I installed is catching some remaining tank rust after sealing it, which I'm thrilled I installed. So, at least that part is eliminated.

I will have to check the air-filter, as I have not pulled it out of the box. I was told when I purchased the bike it was sealed and oiled.

There are no stupid questions right....so what is the best way to test coil voltage? From what I read, there is a primary and secondary. I do have a multimeter on hand.

As for the plugs, I installed new boots which seemed to help even things out. I pulled them after a post-work ride yesterday and all four were fouled with black soot. So, at least #2 is doing something.

How many miles on the engine? Have you run a compression test on it to see where things are at? It could be a coil problem but they usually show up once the bike has run for 10-15 min and at that point, 'typically' they just fail open and the bike dies and/or drops two cylinders.


As Cliff mentioned, double check the air filter. There have been several posts where people have over oiled the filter and it will cause the bike to run rich.

Also, what is going on with the #2 plug? If is appears to be more fouled and sooty than the rest, it may still be issues with your fuel supply.

[GSOH]

the engine has about 6,500 miles on it. it was replaced by previous owner. I have not run a compression test but that will be on the list.

Black soot on the plugs would mean running too rich? Right now I have the air/fuel mixture screws at about 2.25 on each cylinder. Initially #2 appeared dry and I opened up mixture screw about 1/2 turn and now is sooty.

bike still dives down to around 500 or so rpm when at idle.

How many miles on the engine? Have you run a compression test on it to see where things are at? It could be a coil problem but they usually show up once the bike has run for 10-15 min and at that point, 'typically' they just fail open and the bike dies and/or drops two cylinders.


As Cliff mentioned, double check the air filter. There have been several posts where people have over oiled the filter and it will cause the bike to run rich.

Also, what is going on with the #2 plug? If is appears to be more fouled and sooty than the rest, it may still be issues with your fuel supply.

[Dave8338]

the engine has about 6,500 miles on it. it was replaced by previous owner. I have not run a compression test but that will be on the list.

Black soot on the plugs would mean running too rich? Right now I have the air/fuel mixture screws at about 2.25 on each cylinder. Initially #2 appeared dry and I opened up mixture screw about 1/2 turn and now is sooty.

bike still dives down to around 500 or so rpm when at idle.

YES, black soot is a sure sign on an engine with only 6500 miles on it, that it is running rich.

The screws that you are mentioning, are air screws so by turning them out, you should be leaning out the mixture.

[GSOH]

YES, black soot is a sure sign on an engine with only 6500 miles on it, that it is running rich.

The screws that you are mentioning, are air screws so by turning them out, you should be leaning out the mixture.

Ok, I'll fine tune those a bit more and see if I can lean it out a bit. I'll check the air filter as well.

[Chromedome]

Hi, Check the air filter that it isnt over oiled, i know, hard to believe something so simple could be causing alot of ypur problims but do check it. I did the carbs on my 850 with help from these guys on the forum but couldnt get her to run right afterwards. Id bought a new aerosol of Castrol foam air filter oil cause id wanted to do it right, sprayed on just the right amount and mixed it through, mind you i was suspicious as it was almost as thick and more sticky than molasses, anyway, washed it out and replaced it with engine ? oil, problim solved, hope this helps. Stephen.

[Chuck78]

His bike has had a problem of when you try to go to hold the throttle open at half or more, it revs up, bogs down, revs up, bogs down... almost indicating it is starving for fuel. If you try to keep the revs up a lot, it will pop and backfire a lot, and at a certain point in the throttle opening, it will start blowing out black exhaust smoke. This would indicate too rich, as the plugs indicate. Valves were checked by previous owner and adjusted. It was running awesome for the first week on the road, but then got harder to start and having higher rpm/throttle problems.

I suspected maybe a failing igniter having electronic advance issues (converted from mechanical advance), but that doesn't answer all the questions.

Too rich at half to full throttle on a carb that supposedly has the original size needles and main jets, that sounds strange. Pulling the air filter entirely has no effect on the problem. still revs and bogs, blows black smoke, and backfires. We pulled the air filter entirely and ran it without it, and it made no difference in the running condition or symptoms.

If the needle and seat were not sealing, it could be flooding out the carbs, and he did say that his fuel mileage is not good (of course if not running right!), but the fuel bowls don’t have the handy hose port on the drain to check the fuel level with a clear hose like the KZ650 BS32's or my 77 GS550&750 VM carbs. Maybe there is an adapter to buy that threads into the bottoms of the carbs since there is no hose port???

[GSOH]

I may be on to something here... I checked the coils today with no leads running to them from battery (the bike has the coil relay mod from PO). Both sides read 4.5 ohms and the secondary both read 12.5 +/- 0.5k ohms. According the factory service manual, checking with a multi-meter, I should get 3-5 ohms for primary and 30-40k for secondary! Perhaps this is the reason the bike is running super rich!?