Float level.

[spyug]

I'm still trying to figure out why my carbs won't hold an idle. As I mentioned in previous posts, it seems like they run out of gas. When first started, on choke, they work fine and after a minute or two as the bike warms up its possible to shut off choke altogether and it will hold idle at around 1200 to 1500 rpm. After a few minutes, the idle starts to drop.

When it gets to 1000 or slightly lower it almost dies and application of throttle will kill it if it doesn't stop itself. It can sometimes be recovered with the choke. All of this makes me think its needing more gas.

Looking at the schematics for the carbs and reading everything I can, I'm now wondering if float setting have anything to do with it. I must admit that I have not measured float height in these carbs as I assumed they were correctly set (since the carbs ran fine before when on the parts bike) and I have not monkeyed with them.

I am waiting for a new set of o-rings and will measure the floats when I pull the carbs apart again. I guess my question, at this point, is just how critical is it to be accurate with float height. I notice in the manual there is an allowance of + or - 1mm which of course is not much but I also don't see how they could get out of their original setting anyway.

I'm grabbing for straws here folks. Any thoughts please?

cheers,
Spyug

[7981GS]

Test the petcock.
Unless some widget has messed with the floats in the past, they would still be at the factory settings.

Eric

[spyug]

Well I should have mentioned it is doing this while hooked up to an I/V bottle and not the tank, so its not the petcock.

I'm inclined to think I'm dealing with an air leak situation rather than a problem with floats but as I mentioned I'm grasping at straws so I'll look at anything.

thanks for the input.
Spyug

[MisterCinders]

Definitely check the float height. If the float level is off, it will make the bike lean or rich through out all the jet circuits.

When you pull the carbs apart (and you did that to clean them, right? Right?), you disrupt the floats. So you should check the levels when You put them back together. Sometimes the check confirms that the floats went back in unchanged, so great. If you managed to bump the floats during the rebuild or get them swapped across carbs (e.g., float from No. 1 gets put into No. 2), that can throw off the float levels. So check them during the rebuild.

[spyug]

When you pull the carbs apart (and you did that to clean them, right? Right?), you disrupt the floats.

I'm trying to follow this thought.

When cleaning the carbs , I always totally dissasemble them so yes the floats come out. I'm not sure how removing them disturbs them , however. I do put all the parts in individual containers so what comes from one carb goes back in the same carb afterwards.

As the metal "tang" on the float is not easily adjusted without the use of tools I don't see how the position can change when the components are reassembled. The fit on the pivot rod is fairly tight as well so there is little to no slop in the movement of the float that might account for changes.

Despite that, I guess you are saying even small changes can cause issues. I am planning on checking the measurements when I do rebuild next.

Thanks,
spyug

[MisterCinders]

I'm trying to follow this thought.

When cleaning the carbs , I always totally dissasemble them so yes the floats come out. I'm not sure how removing them disturbs them , however. I do put all the parts in individual containers so what comes from one carb goes back in the same carb afterwards.

As the metal "tang" on the float is not easily adjusted without the use of tools I don't see how the position can change when the components are reassembled. The fit on the pivot rod is fairly tight as well so there is little to no slop in the movement of the float that might account for changes.

Despite that, I guess you are saying even small changes can cause issues. I am planning on checking the measurements when I do rebuild next.

Thanks,
spyug

You are correct that it is difficult to accidentally shift the tang on the floats. But you can knock a float arm out of whack making them uneven. You also rightly note that keeping the parts in containers to avoid mixing them is the right way to do things. But parts get jostled, and things happen.

If you don't change the tang, and keep things straight and orderly, then checking float levels will be easy. They will be at the same level you started with. When I did my carbs this weekend to adjust some jetting, it took a few minutes to check floats. They were fine and needed no adjustment. But 5 minutes of measuring confirms that, and rules out a possible cause of mixture problems for all the circuits, fuel flooding, etc.

[JEEPRUSTY]

I have dis-assembled and re-built my carbs and it would be hard to alter the float tangs unless you were deliberately trying.

Spyug you are digging yourself into a hole of despair.
The only issues I had with running that were not clearly electrical has been leaking intake o-rings............

[spyug]

The only issues I had with running that were not clearly electrical has been leaking intake o-rings............

I guess I forgot to mention that but I did change the carb boot o-rings this past weekend and that had no effect at all. She still drops idle and dies and dialling in the idle knob doesn't do anything.

Spyug you are digging yourself into a hole of despair.

Truer words were never spoken my friend. I have new rings on order from Mr. B and they will go in as soon as I get them. If that doesn't sort things I will really be deep down in the hole of despair. Pray that I don't end up there.

Cheers folks,
Spyug

[7981GS]

I have dis-assembled and re-built my carbs and it would be hard to alter the float tangs unless you were deliberately trying

I agree with Jeep.

Eric

[tom203]

Before it does this dropping idle routine, does fiddling with idle stop screw act normally? I don't see how a slight difference in fuel level would cause your problem, but can you jamb some clear tubing in bowl drain holes ,hold it vertically and watch what happens as idle falls off ?

[Nessism]

Verifying the float level is part of the carb rebuild process, and if you want to do a proper job, verify the fuel level too. I don't know if this is the root cause of the problem at hand, but if you verify the fuel level is correct you won't be here in this thread wondering.

[Guest]

I'm still watching your situation with interest but you keep changing threads on me

I was going to pull my tank off over the weekend and watch the mechanical operation of the carb linkage when I adjusted the big idle screw but never got to it. My 550 is suffering a similiar fate but mine is running very well right now (except for the idle falling out), I just have to feather the throttle a little at lights or stops. It's much improved from where I started. I've been where you are at and went threw my carb rack 3 or 4 times in the last year. I'm hoping when you have an answer I'll have an answer (or vice versa) Good luck

PS Did you do a full check of electrics? R/R at the top of the list.

[spyug]

PS Did you do a full check of electrics? R/R at the top of the list.

Yes, but that was covered in one of the threads I changed on you

At this point, I'm setting aside anymore pondering on this until I get the o-rings from Robert and get them in . At that time, I'll do a more thorough rebuild and will check the float height and fuel level too (once I figure out how to do that).

I will report back on that once completed.

thanks guys,
Spyug

[MisterCinders]

Fuel level is easy. Get that gauge from Z1 for like $10.

[haztoys]

Fuel level is easy. Get that gauge from Z1 for like $10.

Then set the float a little lower then Suzuki spec calls for ...