carb trouble's!!??

[kpotter16]

(83 gs750 es Mikuni carb)so this is what its doing.. when i start it on full choke itll idle to about 4500 as i let the choke off itll go down. but if i let it fully off or twist the throttle it dies. i havent sinced it yet because i havent had it idling good. i am going and getting an adapter tomorrow so i can check the float level thru the bottom drain plug thinking that i set the levels wrong. any ideas? and also a question where should the idle screw be set to, somewhere in the manual it said all the way to the left but i didnt think that could be right, and i closed the mixture screws and turned them back 360 from what i heard that was right for just getting it started.

[Octain]

(83 gs750 es Mikuni carb)so this is what its doing.. when i start it on full choke itll idle to about 4500 as i let the choke off itll go down. but if i let it fully off or twist the throttle it dies. i havent sinced it yet because i havent had it idling good. i am going and getting an adapter tomorrow so i can check the float level thru the bottom drain plug thinking that i set the levels wrong. any ideas? and also a question where should the idle screw be set to, somewhere in the manual it said all the way to the left but i didnt think that could be right, and i closed the mixture screws and turned them back 360 from what i heard that was right for just getting it started.

Choke it just enough to keep it running for a few minutes decreasing the choke to maintain a steady idle till it runs with no choke at all. Then and ONLY then you can touch the throttle.
If this wont work then there may be other problems. More than likely something with the carbs.
The idle screw should be set at around 1k rpm's.
Have you cleaned the carbs according to basscliffs tutorial?

[BassCliff]

Hi,

Didn't you just start another thread an hour ago bout the same thing? Have you cleaned the carbs and/or done any of the maintenance I mentioned in the other thread? Have you gone through the maintenance lists in your "mega-welcome" and addressed all of the usual issues? There are maintenance steps that must be performed in order to establish a baseline for further troubleshooting and repair.


Thank you for your indulgence,

BassCliff

[kpotter16]

( yea i did post it on a different thread) ive rebuilt the carbs replaced everything that came with the rebuild kit and soaked the carbs, cleaned, and blew air thru them. im guessing that the float levels wrong but im just speculating. when measuring the float level where exactly on the float and where exactly on the carb do you measure from. in the maunual its a really dark picture and is hard to see where they measure from. theres a lip on the carb where the bowl sits inside. do i measure from that lip or from the inside of it. this could be the problem.

[Steve]

... when i start it on full choke itll idle to about 4500 as i let the choke off itll go down. but if i let it fully off or twist the throttle it dies....

Sounds normal so far. If it goes that high on full "choke", don't use full "choke". Try about half or so. You will soon find the 'sweet spot' where it will start and run at 2000-2500 rpm while it warms up. As it warms, it will run faster, you can adjust the "choke" to keep a reasonable speed.

Because of the way the "choke" (it's actually an "enrichener" system) works, you can NOT twist the trottle at all, or you will override it.

... i havent sinced it yet because i havent had it idling good. ...

I hope you mean "synched", as in "synchronized", but please realize that synching the carbs is part of getting it to idle well.

... i am going and getting an adapter tomorrow so i can check the float level thru the bottom drain plug thinking that i set the levels wrong. ...

Great idea. Some day, I'm going to get or make one (or more) of them for myself.

... and also a question where should the idle screw be set to, somewhere in the manual it said all the way to the left but i didnt think that could be right, ...

Presuming you are talking about idle speed, it should be set about 1100 rpm.

... and i closed the mixture screws and turned them back 360 from what i heard that was right for just getting it started.

Where did you hear they should be set, and where are they set now?
Regardless, start with them out three turns from lightly seated. After the bike is running and warmed up, you will need to synch the carbs, then slowly turn each idle mixture screw in until the engine idles a little bit lower, then back it out about 1/8 turn and go to the next screw. You may find that they end up between 2 and 2 1/2 turns out, but start with 3.

.

[kpotter16]

( "Where did you hear they should be set, and where are they set now?
Regardless, start with them out three turns from lightly seated. After the bike is running and warmed up, you will need to synch the carbs, then slowly turn each idle mixture screw in until the engine idles a little bit lower, then back it out about 1/8 turn and go to the next screw. You may find that they end up between 2 and 2 1/2 turns out, but start with 3." )

right now i have it set one complete turn from completly closed, so your saying i need more then that. as in 2 2 1/2 FULL turns instead of just one like i have it now.

[Steve]

No, please read it again.

I said:

..., start with them out three turns from lightly seated.

Yes, that is THREE full, 360-degree turns from lightly seated.

Start the bike that way. You may not need as much "choke", but it will run quite nicely.

Warm the bike up, then do your fine-tuning to the mixture.

You may find that they end up between 2 and 2 1/2 turns out, but start with 3.

Hey, looky there, I had even repeated it to emphasize it.

And you quoted it when you asked where to set them.

I should emphasize, though, that synchronizing the carbs should be part of this process,
because if the carbs are not supplying equal portions to the combustion, it will be harder to tell which one is doing how much.


.

[kpotter16]

so i set the idle mixture 2 1/2 turns and started it with full choke, it didnt rev to 4500 it went to about 2500 then ran for a minute or two and died then got it to do the same thing one more time but it wouldnt stay runnning..

[Steve]

I give up.

The suggestion is given (more than once) to set the screws to THREE turns, yet you insist on going to 2 1/2.

Yeah, they may end up there, but that does not mean it's a good place to start.

I will let someone else try now.

.

[BassCliff]

Hi,

It sounds like you're making progress. Whether you start with the idle mixture screws at 2.5 or 3 turns out may not be as critical as adjusting them properly once you get the engine to idle steadily. Steve gives good advice. You can also try the instructions in the "highest idle method" article on my website.

Also on my website, in one of the carb sections, are pictures of exactly where to measure and adjust the float height. It is a very straightforward measurement and it's usually best if you set them right in the middle of the range.

Do you have the airbox installed? Is it properly sealed? Do you have a clean, lightly oiled air filter installed? Have you tested your petcock for proper operation? Are the vacuum and fuel hoses properly connected and in good repair? Keep us informed.


Thank you for your indulgence,

BassCliff

P.S. Feel free to click the blue underlined links above to take you to the exact spot on my website with pertinent information.

[kpotter16]

thank you guys i appriciate the help, im a newb at this and learning as i go.

[BassCliff]

Hi,

I'm still learning too!
Guys like Mr. Steve have taught me everything I know.

After you put your carbs back together, did your "bench sync" them? This means to synchronize them "by eye" just to get them running well enough for further adjustments. The procedure for bench sync is also on my website.

One more thing, the float height measurements are done without the float bowl gasket installed.


Thank you for your indulgence,

BassCliff

[kpotter16]

hey! got it running thanks you guys for your help.. ended up being my float hight was off and was causing all the trouble.

[Datsa Noydb]

Where did your mixture screws end up?

I saw several settings mentioned.