bs34 floats...?

[Bob Kelly III]

xjwmx : I believe you might have the wrong idea about the tube ....and using it for viewing the level of the fuel in the float bowl....
as long as you don't use 12 feet of fuel line and lay it down and let it fill up you will be fine seeing the level of the fuel as the fuel will go into the tube and if you raise the tube the fuel will go back into the float bowl not the tank (obviously it can't) that tiny amount of fuel in the line
won't mess up the level reading at all ..... but with a line attached and held up to the side of the carb and then the drain screw opened
it will flow into the tube and stop at the fuel level in the bowl.....
of course you know this , but you made it sound as if moving that hose even a small amount will screw up the reading.... and it won't !
i teaspoon of gas one way or the other isn't going to muck up the reading !
.......
All my life I've set the fuel level about 1/4" below the top of the float bowl on almost every bike I have owned with no ill effects ...and NO WASTED GAS from going up steep ramps or unclimbable hills but this xs650 is different I have set them to the top of the bowl like the manual said..... simply because I was tired of screwing with the carbs and wanted to be done with it once and for all LOL
so I see no reason that the fuel level in the bowls could be a little less than what the manual calls for .... I expect it would run and preform just fine.... it may wind up being a few parts per million leaner than normal though.....because it takes a bit more vacuum to pull the fuel from that depth.... but it's more or less all relative ... as long as the jets are covered good and can't possibly suck air you are good to go !
..... but that is THEORY.... and if your setting your carbs do it the way the manual says !
LOL
Bob.....

 

[gggGary]

Well i wasn't a one kick wonder, took me 20 or 30 before it would stay running and rev smoothly but it's good to go now. Idles smooth revs and returns to idle smoothly. I have video but the sound is poor so it doesn't give you much of an idea of how it sounds, runs. Maybe I'll roll it out in the drive and try some video again. front brakes aren't done yet so not too anxious to go up and down the road. I'd call the carbs a victory, they should be synched on the bike yet and the idle mix needs to be dialed in.

 

[xjwmx]

Did you do the shaft seals on these? What's your thing for insuring the screws in the throttle plate stay put?

 

[Bob Kelly III]

Way to go Gary !!!!! at least it Runs ! that's allot further than you were yesterday ! LOL
get it going so you and the wife can go for rides together ! that has been a dream of mine for years ! unfortunately she would rather follow me in the car ..... HAHAHAHAH!
.....
Bob.........

 

[Bob Kelly III]

well, it runs and don't leak so the float setting must be the way to go ! proof !!!!!! hahahah!
THANKS GARY !
....
Bob.........

 

[gggGary]

Did you do the shaft seals on these? What's your thing for insuring the screws in the throttle plate stay put?

Yes new shaft seals, pretty much every carb I open. I used blue locktite and allen head screws, first time I've tried the locktite.
I had a set of dry Uni foam pods on it and went down the driveway and road a bit, but she was mighty lean, had to really work to get it to pull. Will post up pics I took of the fuel level via the tube method, slightly below the bottom of the carb. Want to check timing (TCI), put on the factory airboxes and get the carbs synced. May have to jet up for the mufflers. This might be the tipping point to get me to set up the wide band O2 air fuel ratio gauges.

 

[weekendrider]

Is that the commando package? Aren't the headers larger if it is?

 

[TwoManyXS1Bs]

Hey, Bob, let's see if we can run a curry comb thru this.

...float height is very critical in these carburetors....there is no doubt about that !

xjwmx : I believe you might have the wrong idea about the tube ....and using it for viewing the level of the fuel in the float bowl....

... if you raise the tube the fuel will go back into the float bowl ... that tiny amount of fuel in the line won't mess up the level reading at all .....

... you made it sound as if moving that hose even a small amount will screw up the reading.... and it won't !

...i teaspoon of gas one way or the other isn't going to muck up the reading !

... I see no reason that the fuel level in the bowls could be a little less than what the manual calls for .... I expect it would run and preform just fine....

I took measurements and made calculations that apply to BS38 float bowls. The BS34 bowls are different, but these values should be close.

Carb trivia of the month:

1 teaspoon is roughly 5cc.
A 1mm change in float height is roughly 2.5cc
1 teaspoon of gas would show up as 2mm of bowl fuel height.

Using a 1/4" (6mm) tube for the "clear tube method", 3.5" (90mm) of fuel in that line is 2.5cc, and flowing that 3.5" worth of fuel back into the bowl would raise the fuel level by 1mm.

A typical XS650 running at 60-70mph cruise mode will be burning roughly 1.2cc of fuel per second. If the petcock(s) were to be turned off during this cruise mode, divided amongst the 2 carbs, that burn rate will drop the fuel level in the bowls by 1mm every 4 seconds.

The BS38 float bowls will each hold about 42cc worth of fuel, 84cc total.
That's about a minute of runtime fuel at cruise mode, until it quits.
I confirmed that on mine, but after 20 seconds the carb response starts to show the beginnings of fuel starvation. That 20 seconds translates to about a 5mm drop of fuel level.

Use these numbers at your discretion...

 

[gggGary]

Is that the commando package?

Kinda personal there buddy!
Small inlet "commandos", on early factory headers, mufflers have welded metal internal baffles (not straight through) so not super free flowing. Kinda surprised me it's so lean. Fuel levels

will adjust, Need to double check for inlet leaks, reused the inlets, gaskets that were on the bike since 1981. ignition components not checked at all.
All of yesterday was kind of a "thrash" lots of "maybe" OKs, it'll do's, not the way I prefer to work. up and down the road in teeshirt and shorts sitting on the frame with no front brake, all in the interest of science......... What me worry?

These uni's are a nice fit....

 

[Bob Kelly III]

LOL OK 2M you got me ...I guess it's more critical than I thought !!!! 1mm doesn't sound like allot but evidently it is !!!!!! I'll make a mental note of it !
Very interesting figures you have there ! .....how did you come up with the 1.2cc of fuel per sec at 60~70 mph ? I've always wondered about that !!!!!! ....and how much that can vary without going so lean it melts pistons !
....... Nuttin' like a curry comb for getting the knots out eh ??? LOL
thank you !
.....
Bob........

 

[Bob Kelly III]

Gary ! that is what we used to call a GREEN WEENY air filter ! I happen to Love those things ! best air filter on the planet because you can wash it real good and put fresh oil on it and go for another 1000miles..... and you call them UNI filters....... where's your sense of tradition !?!?!?! LOL
edit.....
......umm.... aren't those float/gas levels a bit low ? i mean shouldn't the fuel be up to the gasket surface ?

Bob........

 

[madjap]

Hi madjap,
either your hope of marital bliss was interrupted by a local earthquake or you really should reconsider taking whatever meds you are on.

Tripled up on my meds per your suggestion Fred... Seems to be helping. My wife is now naked and SITTING in my coffee cup!

 

[madjap]

MY FLOATS ARE HERE! MY FLOATS ARE HERE! Gotta go out in the 105 degree garage and get to work. I swear. I'm going out there. In just a minute. Just got back from a 150 mile thru the Black Hills on the ol' Electra Glide. Never misses a beat that damn ol' Evo! Ok, air just kicked on in the house... Soon as it kicks off, I'll head out guys. Will post results. Soon.

 

[Bob Kelly III]

Good luck .... soak your t shirt and dunk your hat ! it's the only way to stay conscious working in the heat ! ..... seriously !
....Bob.........

 

[madjap]

Well, I came back in to double check some of your guy's's's information on measuring points. Here is an interesting thing I've uncovered. Bear with me, terminology aside... got my new floats put in. HOWEVER, I noticed that the on the LEFT carb I could NOT get the float to go AS FAR UP into the carb body as I could the RIGHT carb. Now, I've got em mounted upside down on a board and set level on level. When they're on my bike they are just SLIGHTLY off level and I mean just by an mm or two on the bubble level, OK? pretty level on the bike tho. So I set em level on level on the board. So, here I am trying to get that left float to go further into the carb body (not the float BOWL - the body). Like it has to do to shut OFF the fuel flow. Something is stopping it on the left side. I swapped floats from side to side. no change. put old floats in. no change. put another old set in. no change. It's hitting. I figured out it's hitting on an angled galley(?) that runs from the PILOT jet(?) into the carb body. So, I'm like WHY!???? Looks exactly the same carb to carb. So, I've MELTED the float where it was hitting with a red hot knife and reformed that part. Now it seems to go up into the carb body exactly like the other side. All 3 sets of floats I have that came OUT of xs650's carbs all measured and looked identical in shape and size (except for the shaved up ones, but I'm sure they WERE the same). WHY do I have one carb with a 'bigger' or repositioned galley??? Anybody see THIS coming? I'm taking a break before I do the float level sight gauge test, but just wondered. No pics yet because I'm dirty and tired. EVERY SINGLE float (plastic) I tried hit in the same spot on that galley. gggGary? Anything? EDITIED: PILOT jet, not MAIN jet...

 

[Bob Kelly III]

Remember if you cut into the float you'll have to re seal it so gas doesn't get into the float....
only thing I can figure is that all the floats are the Wrong ones ! or perhaps you have one BS34CV carb and one BS38CV carb ( just guessing)
what year is this beast again ?
....
Bob......

 

[madjap]

Well, that fixed the gas overflow problem. Sealed it up nice n tight! It runs raggedy at an idle and misses and sputters when I try to hold steady speed, BUT it accelerates OK and NO gas running out now! I'm running unk year BS34's on a 1972 XS2 650 motor. Tomorrow I might set her up level and check my float levels with the sight tube. I'd like to thank everyone for their interest and help on this. THANKS!

 

[nj1639]

'80 bs34's came with brass floats, '81 were the first year with the plastic floats and had a pull out choke. '82 and '83 had the plastic floats but had the cable actuated choke.

 

[Bob Kelly III]

I suspect you will find the idle air screws are way too lean On mine, the factory set them at 3/4 of a turn out for EPA reasons and put a cap over them so I am not sure if yours are the same or not .... I finally set my air screws at 3 turns out from the seat .... Personally I have no idea how they ever ran at idle before ! LOL......
look up the Dead cylinder test in the tech section, and set the air screws doing it that way,.... after I did that, the idle was perfect ! it lost all the raggedness in that process !.
then make yourself a carb synchronizer and sync the carbs then it will really run good ! ( providing you don't have something else amiss! LOL)
glad you got the over flow problem solved ! I was beginning to wonder what the heck was going on ! LOL ! was it cutting into the float that solved the problem ? I would have just twisted the float by using plyers on the bracket, if you try to twist the metal frame with the float there's a 50/50 chance the float will snap off ! ( Been there done that..... J.B.Weld glued it back on ! )
the dead cylinder test is a crucial one it sets the running mixture at Idle so each cylinder gets the perfect amount of fuel at idle !
.....
I got my brass plugs out of the carbs with them on the engine I drilled a 1/8" hole (be very careful not to go deep with the drill, you can destroy the screw !) and then used a drywall screw, blunted the end, and screwed it into the hole I just drilled and then used a flat crow bar to pull the long screw and brass cap out.... it worked slick and underneath that cap is the air screw !
.....
here's a link to the carb section in the technical reference ....
http://www.xs650.com/threads/cleaning-carbs.3/
......have a good one ...... oh and sure wish My wife would fit in my coffee cup ! LOL
.....
Bob.........

 

[madjap]

Yeah, I only THINK these carbs are 1980's... I have a drain plug on the bottom of the bowl (no side screw to CAREFULLY drain, just the 'drop the plug and watch gas pour down your wrist' style...), they came to me with the air idle screw plugs removed and I put new air mix screws and washer AND O-rings in. I'm set at 3 1/4 turns out BUT I did NOT do the dead cylinder test, so that will be next. I have a mercury manometer from days past, so I can easily do that. WHAT will I do if I get this thing running smooth and correct...??????? My damn Harley EVO needs nothing EVER. Looks like I'll have to get another project. Sigh...