High idle problems

[natelust]

Hello,
I have a 1982 GS g650. I just recently got it, and must say that i love it. The only problem with it however, is its poor gas milage (around 28mpg) I think that it is related to a problem of high idle.

If the bike is cold and I adjust the idle screw so that the bike is at around 900 rpm, then when the bike is hot, it will idle at about 3800 rpm. Needless to say this is way way too high.

If i adjust the screw when it is hot, to around 900rpm, then it is nearly imposible to get the bike to start cold. If I can get it to start it is with the choke all the way open, and I have to run that way till it warms up. This obviously also kills the gas mileage.

I was having this problem nearly from the start, so I rebuilt the carbeurators, but to no avail.

currently I have it set to idle at about 2200 rpm when hot, and this lets be get away with minimal choke at start up. I still have poor gas mileage however. I was wondering how maybe to enrich my fuel mixture in the carb, so that it would take less gas to get the same bang, and thus get away with lower rpms.

Dose anyone have a suggestion? Or know it this will help?

[BassCliff]

Hey HOwdy Hey!

Hi Mr. natelust,

The symptoms you describe make me think "air intake leak". When you rebuilt the carbs, did you also replace the carb intake boots and O-rings? Seal the air box? Have you checked the valves? There's more suggestions and info here in your mega-welcome!

Dear fellow GS rider,

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)!

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

***************************************
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

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

Salvage/Used

http://www.ricepaddymotorcycles.com

http://www.ozpowersports.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
Online Clymer manuals:
http://search.ebscohost.com/ Click on "Small Engine Repair" then "Motorcycles". User=library, password=library. Note: This link may not work if you are on a school campus.

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)

Click here to visit BikeCliff's website.

[1Bigolebear]

Wow,...I have the exact same problem with that exact same bike.
And I did replace all boots and o-rings...re-built the carbs,....new air filter......
Considering next to read up on how to adjust/check the valves on mine.....
Only with mine,......when coming to a stop somtimes if I rev it up once it will go down to a sort of normal idle......

[natelust]

thanks

Thanks for the quick reply. I didnt replace the boots or seals, though they did look like they needed to be. I simply could not find the part on ridenow to order. If you know a good place to look that would help out alot. Could an air leak really be causing the varying idle settings that much?? that is a surprise to me. I will also take a look at the air box seal. I really didnt pay that much attention to it. Do you have any idea how much mpg this might add? just curious.
thank you

[BassCliff]

Hi Mr. natelust,

There are lots of our favorite vendors listed in the mega-welcome above. You should be able to find any part you need.

A properly running GS650G should get between 45-50mpg most of the time. The more TLC you give your bike right up front, the more smiles per gallon it will give you down the road.

Thank you for your indulgence,

BassCliff

[Zook]

If you didn't pull the pilot jet plugs and richen the pilot screws it will be quite lean, as your symptoms suggest.

You should never adjust the idle on a cold engine. Always do it when the engine is up to temp. When it's cold the engine is very inefficient, so it wants more fuel-so you give it some by raising the idle...but when it's warm, zoom! Up goes the idle.

Pull the carbs and go through them, pull the plugs on the air/fuel mixture screws and set them 2-2.5 turns out from seated. Be gentle when turning the screws in, you can break the tip off.

I'll bet your problem goes away.

[natelust]

thanks again

Thanks again for the reply. The one problem that I have is that the carb I have dose not have the air/fule adjust screws on the top of the carb as shown in the rebuild pdf (ie next to the vacume return line on carb 2) they are just caped off metal with a tiny pin hole in it. So I am not sure how to adjust the air to fuel mixture on this carb. Is this normal for a gs650? is there some other way to adjust?

[BassCliff]

It's under there

Hi Mr. natelust,

You must, very, very carefully, drill out the caps on the mixture screws. Be careful so that you don't hit the screws with your drill bit. Drill a small hole, then stick something in there to pry out the cap.

Thank you for your indulgence,

BassCliff

[Skyboy8950]

Wow,...I have the exact same problem with that exact same bike.
And I did replace all boots and o-rings...re-built the carbs,....new air filter......
Considering next to read up on how to adjust/check the valves on mine.....
Only with mine,......when coming to a stop somtimes if I rev it up once it will go down to a sort of normal idle......

This sounds like a sticky throttle cable...

[1Bigolebear]

It was very free when I put the bike together,.......But I will lube it tomarrow and see if that helps. Thanks for the response.....

[rkubik]

Also make sure you have enough free play in the cable at the engine end. too tight and it will rev high at idle.