Won't idle, dies with throttle and surges

[GSJim]

The title says it all. My bike was running well, but was parked for a few months while I dealt with other non-bike problems. (A main drain blockage and emergency furnace repairs killed the entertainment budget!)

Yesterday looked like a good riding day, so I finshed up the electrical repairs mentioned in my project thread and rolled the bike out for a ride. It took a long time to start and then it wouldn't idle unless I left the choke on a bit. When I tried the throttle, the bike bogged and died. And then it would surge to 3500 RPM and back to 1800 RPM.

The carbs were redone 18 months ago by a really good local mechanic because I had neither the time nor the room to work on the bike. The inside of the tank was cleaned with Evaporust and the petcock is new. The gas in the tank had a bit of Seafoam as a stabilizer.

From a bunch of reading here, I'm guessing that the idle problem could be gummed up pilot jets and the surging could be caused by a vacuum leak. I will try one more time with fresh gas, but I'm thinking that I have no real alternative to a full carb rebuild. Is this correct?

If I need to do the carbs again, I will declare the current season done and turn my rolling rebuild into a full rebuild. That way I can get the important parts off the bike before it gets too cold to work in the garage.

Jim

[Big T]

You can try putting some Seafoam in the tank and riding it for a bit and see if it improves

Otherwise, yank the carbs, pull the jets, put them in carb cleaner for a few hours and reinstall

[BassCliff]

Hi,

It sounds like it's time for some proper maintenance. You'll find "how to" guides for most of this on my little website.

***********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.

What I have noticed at the rallies is that very, very few 850Gs are actually running right. Make VERY sure it's actually running the way it's supposed to before busting out the modifications.

Brian's E-Z and fun plan for GS850 happiness:

1) Seal the airbox and air filter with weatherstripping.

2) Ensure no intake leaks. Spraying WD-40 or water doesn't tell you much, since very small air leaks can cause problems even though they won't suck in enough WD-40 to make a difference. Replace your intake boot o-rings and boots if needed, and seriously consider spending the lousy $28 for new airbox/carb boots.

3) Ensure clean carbs with correct settings, new o-rings, and original OEM jets. No, not just squirted with something. I mean completely disassembled.

4) Check/adjust valve clearances (Manual calls for every 4,000 miles. This is not optional.)

5) Ensure healthy electrical system.

6) Seriously consider upgrading coils and plug wires.

7) Install new, stock NGK B8-ES plugs gapped to .031".

8 ) Fine-tune float height and idle mixture screw to ensure best off-idle transition.

9) Clean air filter and reinstall with only the lightest oil mist -- over-oiling and/or letting the filter get dirty is a common and critical mistake, and will make the bike run funny at low speeds and run rich. This may take a few tries.

10) Make sure the exhaust seals are sealing.

11) Ooh, much better now, huh? You're gonna need upgraded suspension - Progressive or better fork springs and shocks. Set suspension sag appropriately.

12) Upgrade brakes with new pads and stainless lines to deal with all that extra speed.

13) Install new petcock, since I'm going to head to the roof with a rifle if I have to read about yet another #2 plug fouling and failed hillbilly attempts to rebuild the petcock and/or deny there's a problem.

14) Oh yeah -- check compression somewhere in there to ensure the valves and rings are reasonably healthy.

15) You'll probably need new OEM clutch springs -- the clutches last forever, but the springs get tired after 20 years or so under pressure. E-Z and cheap.
***********************************


Thank you for your indulgence,

BassCliff

[BigD_83]

I'm afraid to say it Jim, but it sounds like the pickup tubes and/or pilot jets are clogged up once again.

The strip and dip isn't that bad. I can't recall if YOU"VE done it once already since putting it back on the road, but you just need a few days to do it. There is nothing technically difficult about it (except getting rid of the smell of the Kleen-Flo if you can't source Berryman's).

P.S. this would also be the time to send the bodywork and tank in to Reproduction Decals. I was going to do it, but they are essentially local to you.

[Nessism]

I'd try half a can of Seafoam in fresh tank of fuel. Coax the bike to life and try to figure out which cylinder(s) aren't firing. Then take the bike out for a ride to see if the problem will clear up. If it doesn't clear up within 10 miles, it's time to pull the carbs.

[GSJim]

I'm afraid to say it Jim, but it sounds like the pickup tubes and/or pilot jets are clogged up once again.

The strip and dip isn't that bad. I can't recall if YOU"VE done it once already since putting it back on the road, but you just need a few days to do it. There is nothing technically difficult about it (except getting rid of the smell of the Kleen-Flo if you can't source Berryman's).

P.S. this would also be the time to send the bodywork and tank in to Reproduction Decals. I was going to do it, but they are essentially local to you.

I didn't do the carbs myself. A reputable local mechanic did the work and the bike was running well when he was done with it. I did the electrical repairs and other routine maintenance myself.

Ted (Classic Katana Owners) sends his graphics work to BDesigns in Kitchener, which is even closer to me. I haven't compared the features or prices with Reproduction Decals yet. Ted suggested that I take my tank and plastics to BDesigns for scanning over the winter. The big problem I have is trying to figure out the original colors. My Pure Red is sort of orange and the Sunday Orange is faded.

Jim

[GSJim]

Hi,

It sounds like it's time for some proper maintenance. You'll find "how to" guides for most of this on my little website.

I am a big fan of your little website. Other than the carb cleaning, which I paid someone to do, I am doing most of the work myself as a rolling rebuild. The big issue with my bike was electrical. The stator to regulator wiring in the harness cooked when the stator and regulator blew.

If I have to pull the carbs now, I will terminate the rolling rebuild and tear everything apart during the winter. I have maybe three or four weeks before it will get too cold to work outside.

Jim

[GSJim]

I'd try half a can of Seafoam in fresh tank of fuel. Coax the bike to life and try to figure out which cylinder(s) aren't firing. Then take the bike out for a ride to see if the problem will clear up. If it doesn't clear up within 10 miles, it's time to pull the carbs.

I'll try this first.

Thanks.

Jim

[BigD_83]

I didn't do the carbs myself. A reputable local mechanic did the work and the bike was running well when he was done with it. I did the electrical repairs and other routine maintenance myself.

Ted (Classic Katana Owners) sends his graphics work to BDesigns in Kitchener, which is even closer to me. I haven't compared the features or prices with Reproduction Decals yet. Ted suggested that I take my tank and plastics to BDesigns for scanning over the winter. The big problem I have is trying to figure out the original colors. My Pure Red is sort of orange and the Sunday Orange is faded.

Jim

It's too bad. I had my eye on an '83 NOS tail cowling, but it was from the UK and the shipping was prohibitively expensive. Can they not colour match from the Suzuki Colour codes on their existing patterns?

[Guest]

If you have a portable fuel tank try running good gas right into the fuel line.
My guess is you messed up the petcock.

[GSJim]

Rats. We have two days of cold and rain in the forecast. Thursday looks good so I will try the suggested fixes then and let you know what happens.

Thanks.

Jim

[GSJim]

It's too bad. I had my eye on an '83 NOS tail cowling, but it was from the UK and the shipping was prohibitively expensive. Can they not colour match from the Suzuki Colour codes on their existing patterns?

PM sent regarding the color talk. This might reappear on the Appearance forum later.

Jim

[GSJim]

No joy here. I out some Seafoam in the tank at the end of my last attempt to get the bike going. Today was the first nice day for almost two weeks so I rolled the bike out for another try. I managed to get it running on three cylinders. Number 2 was stone cold. It had spark but almost no fuel. Time to pull the carbs.

The season is now officially done. Disassembly for a full rebuild will start this week.

Jim