GS 850 Carb Problems

[nelson269]

I have an '81 GS 850 and have allready rebuit the carbs 3 times to try and get the bike to run better. When I bought the bike it wouldn't even run. Now it runs but runs better at half choke. I bought a K&N filter for it, its installed in the stock air box. I haven't drilled out the air bleeds yet... Should I??? Also just doesn't seem to have much power and only gets like 20 MPG??? What do I need to do??? buy vacume gauges and sync Carbs??? Thanks

[chef1366]

Print this out and follow it. It is the carb rebuild bible!

http://www.thegsresources.com/gs_carbrebuild.htm

[Steve]

First of all,
BassCliff will be along shortly with his 'official' welcome.


What did you do to "rebuild the carbs"?

Did you strip them down completely and dip them?

Did you replace all the little o-rings inside the carbs?

Did you set the float heights correctly?

Did you set the idle mixture screws out at least two full turns, then fine-tune them later?

Did you do plug chops to verify that you have the correct jets?



Also, where are you? Someone might be near enough to help you, we just have no idea where you are.

.

[nelson269]

I did print out that carb process, and used it. It was a very big help. I bought carb kits and changed all the o-rings. I didn't "dip" them but used carb cleaner and an air compressor to clean them. Yes I did check float heights. I don't have idle mixture screws...kit came with them... I haven't drilled out the stock plugs yet. And I don't know what plug chops are... I live in Syracuse NY. Thanks guys

[BassCliff]

Greetings and Salutations!

Hi Mr. nelson269,

Sometimes there just are no shortcuts. Do it right the first time and, chances are, you'll never have to do it again. That includes carb cleaning. Now let me roll out the welcome mat for you. Pay particular attention to the "Top 10 Common Issues".

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 your, your bike!

Thanks for joining us. Please keep us informed.


Thank you for your indulgence,

BassCliff

[SqDancerLynn1]

The mixture screws are hidden under the little cap on the top of the intake side. YES their are no shortcuts when it comes to the carbs. Starting with the intake Boots & O ring, then a good carb clean Did you resue the original jets??? carb kits have been known to have the wrong ones. also a good sealing airbox

[Steve]

I did print out that carb process, and used it.

That's a good start, but evidently you tried some shortcuts. One of the items in the carb process is to 'dip' the carbs.

I bought carb kits and changed all the o-rings.

If you only changed "all the o-rings" that were included in the carb kits, you only changed less than half of what is necessary.

I didn't "dip" them but used carb cleaner and an air compressor to clean them.

How long has it been since the bike was run regularly? If it's more than a few months, you may have to clean them again, but please dip them this time. The small passages that are most affected by the residue of evaporated gas can not be reached effectively with just carb spray and compressed air. Yes, you use them to ensure the passage is clean once the gunk has been softened by an overnight stay in 'the dip', but they are not quite good enough to do all the cleaning.

Yes I did check float heights.

Did you measure to the correct part of the float? A common mistake is to measure to the very top of the (upside down) float, when you should measure to the bottom of the step.

I don't have idle mixture screws...kit came with them... I haven't drilled out the stock plugs yet.

Unless you have some replacement 'miracle' carbs, you do have mixture screws. They were hidden by the factory under those plugs you have not yet drilled out. After you remove the plugs, note the location of the slots in the mixture screws. Turn each screw in as gently as possible, counting the turns until it lightly seats. Will probably be somewhere between 1 and 1 1/2 turns. Record that. Take the screws out, then use a drywall screw to get out the spring, washer and o-ring. There is a small passage between this screw and the pilot jet that is very easily plugged by gunk. Chances are, this is the cause of most of your problems. Best solution is to 'dip' the bare carb body.

And I don't know what plug chops are.

"Plug chops" is a method of running the bike at specific throttle openings for a while (duration depends on which opening you are using), then using the kill switch to stop the engine, pull the clutch, coast to a safe stopping area, then pull a spark plug or two, to read the color to make sure you have correct jetting in the carbs. Here is a link to an article on how to check the jetting. The best part is ... if you have a stock bike (air filter housing/exhaust pipe), you will likely only need to set your mixture screws out to somewhere between two and three turns, instead of the very lean factory settings.

I live in Syracuse NY.

Thanks. Now go to the "User CP" (that's User Control Panel) link in the upper left corner of the screen, and edit your location. While you are there, create a signature that shows what bike you have so you won't have to remember to add it every time you ask a question. We have a few New Yorkers in the group, not sure which one of them is closest to you.

.

[nisom512]

I read this thread over and I didnt see a link to the O-ring site I know it's on basscliffs site but just to make it a little easyer.

https://www.cycleorings.com

you have the BS or also known as CV carbs and they are the large ones when you order you intake o-rings

you should also get intake 0-rings I dont know about any one else but I just did mine on my 81 GS850 and holy crap they were super hard and when I held them in my hand I accidentally crushed them. so these are a big deal I did them on my GS550 and there was a world of differance when I ran and idled

Good luck
Jake