I want a smooth '79 850 GN

[Rob81]

Hey guys,

I have a 1979 GS850 GN. She was hiccuping on cold starts and hesitating when the throttle was being pulled.
-I replace the intake boots and O-rings.
-This solved the hesitation, and the throttle response. Still hiccups a little.

-After a ride on the freeway, the bike slowly idle's down and when rev'ed, she sits high RPM and floats down slowly.
-Sometimes at lights, once the rpm's are at normal idle, she wants to die.

Seems its either too high or too low. I thought the intake boots would solve this but I guess theres more. Any ideas?

[Dave8338]

Is the bike stock (air box, filter, pipes)?
Have you completely torn down and soaked the carbs and replaced all the o-rings in them?
Sounds like a lean condition.

[twr1776]

Today 04:17 PM Dave8338 Is the bike stock (air box, filter, pipes)?
Have you completely torn down and soaked the carbs and replaced all the o-rings in them? Sounds like a lean condition.

I agree with Dave and here is some info from Bass Cliffs website on 850's. I am sure he will be along shortly for your "official" greeting.

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

[BassCliff]

Greetings and Salutations!!

Hi Mr. Rob81,

Gosh, Tim and Dave have already done most of the work.

Anyway, yes, it sounds like there is still a problem with either the air intake system or dirty carbs. Make sure the airbox and air filter are properly sealed (there are pictures on my website). Check the spark plugs and caps, charging system, etc. Now without further ado, let me say I'm glad you've joined us and "Howdy!".....

Here is your very own magical, mystical, mythical, mind-expanding "mega-welcome". Please take notice of the "Top 10 Common Issues", the Carb Rebuild Series, and the Stator Papers. Now let me roll out the welcome mat for you...

Please click here for your mega-welcome, chock full of tips, suggestions, 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. Don't forget, we like pictures! Not you, your bike!

Thanks for joining us. Keep us informed.

Thank you for your indulgence,

BassCliff

[SqDancerLynn1]

Have you done a carb sync ? That will help

[Rob81]

Thank you to both Dave and twr1776.

I will go through twr1776's list and get her all tightened up. My next thing is the O-rings, then domino's from there!
I'm planning a trip and want to be all squared away before I leave.
Ill keep the updates posted.

[twr1776]

One more "shameless" plug for Cliffs site. Mandatory reading IMHO for any new GS owner. If you are planning a trip I would suggest adding a spline inspection and grease before you go. You must remove the spline from the wheel to inspect it properly even if it looks OK from the outside. You should also find out how old your tires from the date codes, if you are unsure there are many good tires available in all price ranges. The search button is your friend.

http://members.dslextreme.com/users/bikecliff/images/rear_wheel_removal.pdf

My almost oops spline story

http://www.thegsresources.com/_forum/showthread.php?t=149097

[Larry D]

Welcome !!!

I don't think there's much more to say......go completely through that list and you'll have a great, reliable bike.

.....Nice new avatar, Tim.

[twr1776]

Just trying to keep up with you Larry.

[rustybronco]

That machine of yours is capable of running flawlessly. just ask Wallowgreen.
in fact it may surprise you when it's running correctly.

we'll get it there for you.

[willie]

If ya wanna make it perform even better, after you've taken care of everything previously recommended, install a coil relay. Do so and you too will become a believer.
Willie

[azr]

Lots of good advice. Sounds like you're already on your way to having a good runner. Something I did recently that really helped was a thorough wiring cleaning. Cleaned all the grounds and every connector and rewired all my grounds to my r/r following Posplayr's advice. Great bike you've got there and I've made good use of that kick start more than once!

[Rob81]

Thanks AZR.
(Willie)- The coil relay? Is the the electronic device that replaces the points?

[bwringer]

A '79 would have the good harder rear wheel spline, but you should definitely make sure it's properly lubricated with 60% moly paste. It's about $12 for a lifetime supply at any Honda dealer.

Also, your next step is to seal your airbox.

[azr]

Every thing is on BikeCliff's website. Coil mod (which is not replacing your points with an electronic ignintion, which is an excellent idea by the way, but to directly wire positive current to the coils to avoid a power drop to your plugs), wiring harness cleaning, charging system troubleshooting, and anything else you could ever need including manuals. I did the coil mod aswell, just make sure you carry an extra relay with you as they can just 'go'. Make sure you post some more pics of your bike, it looks great. Like your uncles 1000 as well, funny they are the same paint scheme.