82 GS650g - black sparkplug #3

[Tino]

One other check before you go to the trouble of pulling the carbs:

Swap the spark plug wires between #2 and #3. They both fire at the same time, so there is nothing else to change. If you have a bad wire or a bad spark plug boot, the problem will re-appear on #2. This will tell you that it's not the carbs. If the problem remains in #3, try swapping the spark plugs or put a new one in #3. If this does not clear up the problem, then yes, the problem is likely in the carbs.

.

Hello Steve and thank you as well for the reply.

I have replaced all the spark plugs and I cannot yet tell if the 3rd cyl is running rich anymore but what I know is that when I pull the sparkplug wire from the 3rd cyl, the engine is running the same, no stutter no skipping, absolutely no change even in how it sounds. This is valid for idle or if I throtle the engine while not moving. So this tells me that even by replacing the spark plugs, the problems still exists. I wonder if by changing the sparkplug wires between cyl 2 and 3 will move the problem to cyl 2. I will try this.

 

[skidMarkNZ]

IT makes no change in the bikes noise when you take the lead off because it is not firing, you are ALWAYS running on 3 cylinders.

 

[Steve]

I missed the point (if you had made it earlier) where you had changed the plugs. The intent of doing the swap in two steps was to separate the #3 wire from #3 plug. If the problem moved, it would be the wire. If it did not move, it could be the plug or the carb.

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[p_s]

I'm baffled. Since the same coil fires cylinders 2 & 3, shouldn't neither one fire if the cap for #3 is pulled? Does header #2 get hot? But you say the bike dies if you pull the cap on #2.

Maybe the wire for #3 is bad and shorting to the valve cover or something around there?

 

[Guest]

Pull the spark plug cap off #3 and snip the wire until you get good clean wired and thread it back in.

 

[Zooks]

IT makes no change in the bikes noise when you take the lead off because it is not firing, you are ALWAYS running on 3 cylinders.

My thoughts exactly.

Does the bike backfire on deceleration? #3 may be flooding constantly due to a stuck float needle. This happens on my 750 occasionally. #3 just pumps pure fuel straight out the exhaust because there is too much to burn. I just tap the float bowl with my leatherman (coz I always have it on my belt) and it fixes itself. I've been meaning to pull it and clean it out for more than a year.

When the bike is firing on all 4 again you will be amazed at the difference.

 

[Tino]

Hello all again,
I have swapped the sparkplug wires for cyl #2 and #3. The problem stays with sparkplug 3. With the new swap, if I again pull the sparkplug wire #3, nothing happens, same motor idle, but if I pull the sparkplug wire #2, which was before the #3), the engine almost dies. THis tells me there is no electrical wire problem. It must be the carburator #3 and from all I have been reading from you guys, is the pilot jet who is clogged an no fuel gets to it, even though I have ignition going to it, nothing happens, that's why I don't see/hear any change in the motor when the sparkplug wire #3 is pulled.
However the exhaust pipe #3 is also hot after a longer ride, and maybe because the other jet provides gas when bike at higher RPM?

 

[Tino]

My thoughts exactly.

Does the bike backfire on deceleration? #3 may be flooding constantly due to a stuck float needle. This happens on my 750 occasionally. #3 just pumps pure fuel straight out the exhaust because there is too much to burn. I just tap the float bowl with my leatherman (coz I always have it on my belt) and it fixes itself. I've been meaning to pull it and clean it out for more than a year.

When the bike is firing on all 4 again you will be amazed at the difference.

The bike doesn't backfire when I decelerate. If not for the black sparkplug 3 and for the pulling of the sparkplug wire not showing any change in motor behaviour, one would thing everything is OK with the bike, with the exception that it doesn't have much power at higher RPM.
And here is the other dilema. How come I have great power at lower RPM and not too much power at higher RPM if the pilot jet is clogged. Isn't that the one which provides gas up to a certain low RPM. I am very green in Motorcycles/carburation, and maybe what I am asking doesn't make much sense.

 

[BassCliff]

Hee Haw Howdy!

Hee Haw Howdy!

Mr. Tino,

Sorry I'm late with your mega-welcome!

Let it be known that on this day you are cordially and formally welcomed to the GSR Forum as a Junior Member in good standing with all the rights and privileges thereof. Further let it be known that your good standing can be improved with pictures (not you, your bike)![FONT=Arial, sans-serif] [/FONT]

Perhaps you've already seen these, but I like to remind all the new members. In addition to the carb rebuild series, I recommend visiting the In The Garage section via the GSR Homepage and check out the Stator Papers. There's also a lot of great information in the Old Q&A section. I have some documentation on my little BikeCliff website to help get you familiar with doing routine maintenance tasks (note that it is 850G-specific but many tasks are common to all GS bikes). Other "user contributed" informational sites include those of Mr. bwringer, Mr. tfb and Mr. robertbarr. And if your bike uses shims for valve adjustments, send an email to Mr. Steve requesting a copy of his Excel spreadsheet that helps you keep track of clearances, shim sizes and other service work.

These are some edited quotes from one of our dear beloved gurus, Mr. bwringer, with ideas on basic needs (depending on initial condition), parts, and accessories.
***********Quoted from Mr. bwringer************
Carburetor maintenance:

Replace the intake boot o-rings, and possibly the intake boots. Here's the procedure:
http://bwringer.com/gs/intakeorings.html
Here's an overview of what happens with this particular problem:
http://cycleorings.com/intake.html
You'll also want to examine the boots between the carbs and the airbox. There's a good chance these are OK, but check them over.
And finally, if things still aren't exactly right, you'll want to order a set of o-rings for BS carbs from the GS owner's best friend, Robert Barr:
http://cycleorings.com
Once you receive these rare rings of delight, then you'll want to thoroughly clean and rebuild your carburetors. Here are step-by-step instructions that make this simple:
http://thegsresources.com/gs_carbrebuild.htm
***********************************
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.
***************************************
OEM Parts/Online Fiches:

I would definitely double and triple the recommendations to use Cycle Recycle II and Z1 Enterprises as much as possible. These guys are priceless resources. Z1 tends to have slightly better prices, CRC2 has a wider range of goodies available. If you're near Indy and can bring in an old part to match, CRC2 has a vast inventory of used parts.
http://denniskirk.com - Put in your bike model and see what they have.
http://oldbikebarn.com - seems to be slowly regaining a decent reputation, but it's still caveat emptor. They don't have anything you can't get elsewhere at a better price anyway.
http://www.babbittsonline.com/ - Decent parts prices. Spendy shipping. Don't give you part numbers at all. Useful cross-reference if you obtain a part number elsewhere. Efficient service.
http://bikebandit.com - Fastest. Middlin' prices. Uses their own parts numbering system to obfuscate price comparisons -- can be very confusing for large orders. Cheapest shipping, so total cost usually isn't too bad.
http://flatoutmotorcycles.com - Slow. Cheapest parts prices, crazy shipping costs. Don't expect progress updates or much communication. Real Suzuki part numbers.
http://alpha-sports.com - Exorbitant parts prices. Different type of fiche interface that's quite useful at times, especially with superceded part numbers. Real parts numbers. Shipping cost and speed unknown due to insane, unholy pricing.

Stainless Bolts, Viton o-rings, metric taps, dies, assorted hard-to-find supplies and materials, etc:

http://mcmaster.com - Fast, cheap shipping, good prices. No order minimum, but many items like bolts come in packs of 25 or 50. Excellent resource.
http://motorcycleseatcovers.com - Great quality, perfect fit (on original seat foam), and available for pretty much every bike ever made. Avoid the textured vinyl -- it's perforated.
http://newenough.com - You DO have riding gear, don't you? Great clearances, always outstanding prices and impeccable service.
***************End Quote**********************
Additional parts/info links:

GSR Forum member Mr. duaneage has great used upgraded Honda regulator/rectifiers for our bikes. Send him a PM.
New electrical parts:
http://stores.ebay.com/RMSTATOR or http://www.rmstator.com/
http://www.ricksmotorsportelectrics.com/index.php
http://www.electrosport.com/
For valve cover and breather cover gaskets, I recommend Real Gaskets (reusable silicon):
http://www.realgaskets.com
The Rice Paddy (salvage/used)
http://www.ricepaddymotorcycles.com
Carolina Cycle
http://www.carolinacycle.com
Ron Ayers Motorsports
http://www.ronayers.com
MR Cycles
http://www.mrcycles.com
Moto Grid
http://www.motogrid.com
If all else fails, try this:
http://www.used-motorcycle-parts.org/
Used bike buying checklists:
http://www.amadirectlink.com/roadride/Riderresc/checklist.asp
http://www.clarity.net/~adam/buying-bike.html
Lots of good info/pictures here:
http://www.suzukicycles.org
http://www.cyclechaos.com/wiki/Motorcycle_Wiki
http://www.bikepics.com
Basic motorcycle maintenance/repair:
http://www.dansmc.com/mc_repaircourse.htm


Thanks for joining us. Keep us informed of your progress. There's lots of good folk with good experience here.

Thank you for your indulgence,

BassCliff
(The unofficial GSR greeter)

 

[Dogma]

...
However the exhaust pipe #3 is also hot after a longer ride, and maybe because the other jet provides gas when bike at higher RPM?

To be sure you could try it again to see if there is a change in how the bike revs up with half or full throttle when you pull that plug? Don't worry too much about hitting the red line a couple times for this test. Worry about the neighbors maybe...

 

[Smokinapankake]

Tino,

I've got the same problem on my 84 Kat 750, only it's my #2 plug that is black and sooty. I swapped plug leads from 2 to 3 and will check tonight to see if the problem follows the lead. I'm hoping it does. Seems like you have to put a few miles on before the black sooty will burn off the plug, rather than idling in the driveway.

 

[Smokinapankake]

So the problem persists - black sooty on #2 plug, even with the plug leads swapped. But the strange thing is - when I was getting ready to go in to work this morning, I thought "I'll feel the exhaust pipe on #2 to see if it gets hot like the other 3". So, I fired it up, reached down and grabbed hold of 1 and 2, and yep, they both get hot at the same time/rate. So it's not my idle circuit, is it? I mean, it should be getting fuel, right? When I checked the plug yesterday I grounded #2 plug against the frame and cranked it up, got solid spark in broad daylight (in the garage with the door open, about 2:00pm) so I know that cylinder is firing. What else could it be?