more carb issues?

[moparguy]

so new owner here...bike is a 81 gs850..

bike runs ok when choke is open, cant rev, sometimes runs without choke...its kinda dumb how it does what it wants..

bike sat for a few years, carbs have done been cleaned..

and ideas?

[tom203]

so new owner here...bike is a 81 gs850..

bike runs ok when choke is open, cant rev, sometimes runs without choke...its kinda dumb how it does what it wants..

bike sat for a few years, carbs have done been cleaned..

and ideas?

Follow the link to Basscliff's site ( have food/drink handy) and be amazed! Also, be ready to explain "carbs have done been cleaned" or suffer the consequences.

[moparguy]

by cleanin i meant i took them apart, sprayed with carb clean an blew all holes out

[Nessism]

by cleanin i meant i took them apart, sprayed with carb clean an blew all holes out

That is not cleaning. Check the carb rebuild tutorial linked in my signature.

[NeyborDayfid]

From what you're describing it sounds like you have a lean mixture. When you pull the choke you're restricting air and increasing fuel in the mixture which is great for a cold bike because the fuel will want to stick to the sides of the cold cylinder and not atomize. You said it will sometimes run without choke but is that after it's warmed up?
My first questions are this:
Are you running the stock airbox with the stock exhaust?
How new is the battery?
Did you take note of any jet sizes while cleaning the carbs?

That info will put on the right track. Welcome to the forum

[moparguy]

i havnt been able to keep it running to warm it up, stock exaust exaust etc, will be pod filters soon

[NeyborDayfid]

It's possible that the airbox seals are worn and there is an intake leak. The intake boots between the block and the carbs most likely has cracked or just flattened o-rings as that's possibly the most common intake leak. Since you describe it as "doing what it wants" I'm thinking checking for an intake leak might be a good idea. If you can get it running for a bit try spraying starter-fluid around the intake boots between the carb and engine and if you get a rise in rpms then you certainly have an intake leak which would explain the lean mixture. Make sure to peek at the spark plugs and clean and gap them correctly. Buying a new pair is a good idea if they're old.
This process can be a pain to nail down. I hope you have a battery charger on hand.

[kparkfan]

Until you use the link Nessism provided your carbs won't function properly. After you do a proper cleaning and make sure all your carb boots and airbox boots are soft and pliable you will be amzed at how well it helps.

[NeyborDayfid]

I have to second Kparkfan. It sounds like you dipped them and cleaned them well but nothing, and I mean NOTHING beats rebuilding them with a set of Viton O-rings. cycleorings.com has a set for that bike that'll run you less than 20 bucks and you'll know for sure then that you've done it right. He's fast to ship too.
Installation goes quick and then if your boots and intakes are good you might just see the whole problem go away. I had that exact experience on my 850. I had a wandering idle and it was running too hot and smoking and all kinds of ill manners and once I installed the new o-rings on my otherwise perfectly clean carbs all the issues went away.
Do a valve adjustment too if you haven't. Valves get tighter as they wear and can contribute to the leaning of the mixture. It's a fairly straightforward process and there's no point in troubleshooting carbs if your valves are off.
Hope that helps.

[keman]

Yep, sounds like the classic air leaks. Mine did pretty much "whatever it wants" until I replaced the o-rings between the carb to engine manifolds, and replaced the boots from the air box to the carbs.

Even a very small leak there can make the idle run up and down at will, and the engine bog when you try to open the throttle.

Opening up the carbs and spraying them out with carb cleaner isn't good enough because there are some very tiny holes in the jets and such that need to be soaked and cleaned out with a wire. Get a new complete set of carb O-rings, and the manifold o-rings from Cycleorings and do it right. Otherwise you will continue to have random idle issues, and poor performance.

When you are done cleaning them, don't forget to bench sync them and then when you get it running, do a vacuum sync as well.

[Big T]

From what you're describing it sounds like you have a lean mixture. When you pull the choke you're restricting air and increasing fuel in the mixture which is great for a cold bike because the fuel will want to stick to the sides of the cold cylinder and not atomize.

While this is correct for a choke, your bike doesn't have one like that.

Instead, it has an enrichener fuel circuit that adds extra fuel when the choke knob is pulled

[moparguy]

alright neato info guys lol...ill go ahead an dip em, get new o rings an do the valves...now i did some searching but no luck on finding how to do valves on the bike...i know i passed it up

[Steve]

When you pull the choke you're restricting air and increasing fuel in the mixture ..

Sort of, ... almost, ... not quite ... accurate.
The choke on a car does exactly that, but the "choke" on our bikes works differently.
When you pull the "choke" knob there is nothing that blocks the intake of the carb. What happens is that another passage is opened, which provides the rich mixture that is needed. For this system to work properly, though, the throttle has to kept CLOSED to maintain the high vacuum necessary to draw the fuel and air through the enrichener passages. If you open the throttle AT ALL, you will defeat the enrichener system and you will be trying to start the bike on the 'normal' lean jets.

It sounds like you dipped them and cleaned them well but nothing, and I mean NOTHING beats rebuilding them with a set of Viton O-rings.

Where did you get that idea?

..., be ready to explain "carbs have done been cleaned" or suffer the consequences.

by cleanin i meant i took them apart, sprayed with carb clean an blew all holes out

Sounds like one of those half-way "cleanings" to me.


Moparguy, you need to strip the carbs down and dip them, the way it's outlined in the guide that is in Nessism's signature. Until you do that, you won't know whether they are REALLY clean or not, so anything you do is just going to be a guess.

You say you are going to switch to pods. Keep in mind that you will have to re-jet when you do that. In the meantime, are you using any filter on the carb intakes? If not, that's why you can't rev the engine. At the very least, fold a shop rag in half, drape it over the intakes, clamp it over the outer carbs so that it is still somewhat tight over the inner carbs, too. This is not accurate enough for jetting checks, but it will let you ride it around the block.

.

[NeyborDayfid]

Thanks for correcting me Big T and Steve!

Yes, that's absolutely right on these carbs that pulling the choke pulls a plunger on the side and opens an enriching circuit. I knew that because I just installed new o-rings on mine last week. I just didn't say that for some reason.

I don't know where I got the idea that he had cleaned them well but I stand behind the idea that using a new set of Viton o-rings is the only way to be sure that all those rings are pliable and sealing as they're supposed to.

Moving past my corrections, I have to agree that if you are eventually going to go with pods, just get the pods first and then do your jetting. You could be looking at pulling your carbs off a dozen times if you really want to nail down a smooth transition through the entire throttle range. Hopefully that won't be the case and your jet kit will install and play nice but I've read a lot about jetting and installs on here and done a half-dozen of them myself. It's totally worth it when you get there but you probably don't want to have to do it twice.

[Nessism]

I don't know where I got the idea that he had cleaned them well but I stand behind the idea that using a new set of Viton o-rings is the only way to be sure that all those rings are pliable and sealing as they're supposed to.

.

I agree about the new O-rings, and the Viton O-rings are best, but cycleorings.com sells Buna N O-rings. If you want Viton you need to order them yourself. The carb rebuild tutorial linked in my signature has the proper sizes if you have BS/CV carbs.