Sinking Float?

[79XStLouis]

So I did a full restoration on my 79 XS, and it was running absolutely great for a few days. Soon it didn't want to idle without goosing the throttle. When I rebuilt the carbs, both sets of floats had pin holes which I carefully soldered up, but the brass was frail overall, so now I suspect one may be taking on fuel. I am not getting any fuel leakage out of the carb bodies, wouldn't that happen? The bike runs great at speed, just not idle, but the last time out I was hearing some popping in the exhaust note when off throttle and slowing... then again at idle. So maybe I sprung a vacuum leak. Will do the spray solvent test at the fittings to test for vacuum leaks, but wondered if I should also pull the carbs off and rule out leaking float(s).

 

[gggGary]

A quick dip in a cup of hot water will verify that the floats are still leaking (they are LOL) www.650central.com is the hot tip for quality OEM floats. I have bought many from Mike Morse. He's old school real.

 

[5twins]

It's also possible some dirt has made it's way into the carbs and plugged or partially plugged the idle circuits. In either case, an internal carb investigation will be needed.

 

[79XStLouis]

A quick dip in a cup of hot water will verify that the floats are still leaking (they are LOL) www.650central.com is the hot tip for quality OEM floats. I have bought many from Mike Morse. He's old school real.

I submerged my soldered floats in bucket of water for 24 hours and they stayed liquid free. The overall quality of them was pretty fragile from being submerged in gas glue. I'll just replace them with some new ones or oem... where does one find quality floats? I've heard the aftermarket floats are sketchy.

 

[79XStLouis]

It's also possible some dirt has made it's way into the carbs and plugged or partially plugged the idle circuits. In either case, an internal carb investigation will be needed.

God I can't believe that. New filters in the gas tank plus in-line filters in the gas lines. Nothing of any size could've made it into the carbs by my estimation. I hate to tear them apart after just putting them back together.

 

[grizld1]

Believe it. Obstruction doesn't always come from the outside, and it isn't unusual for neglected carburetors to need two or three rounds of cleaning. Scale breaks loose and blocks pilot system passages.

 

[MaxPete]

I hope nobody minds a side question - but if the brass floats were leaking, how the heck do you solder them?

I mean, they’ve been in gasoline and if there was any trace of fuel fumes inside the float - wouldn’t they simply explode when heated?

 

[79XStLouis]

I hope nobody minds a side question - but if the brass floats were leaking, how the heck do you solder them?

I mean, they’ve been in gasoline and if there was any trace of fuel fumes inside the float - wouldn’t they simply explode when heated?

Wrong. The bike sat for a decade or so, the crispy dried tar that was once fuel had long lost its explosive volitility. It ate at the brass over the years and left holes.

 

[MaxPete]

Sorry - not wrong 79. .or perhaps you missed my point.

If the float has been in a carb and fuel has been in that carb and the float has a leak, there will be gasoline fumes inside the little brass body. My question, again, is: how do you solder the float without running into the gasoline fumes?

There must be a way to do it - and I’m wondering what the trick is.

 

[79XStLouis]

Sorry - not wrong 79. .or perhaps you missed my point.

If the float has been in a carb and fuel has been in that carb and the float has a leak, there will be gasoline fumes inside the little brass body. My question, again, is: how do you solder the float without running into the gasoline fumes?

There must be a way to do it - and I’m wondering what the trick is.

Again, in my case it was a non issue. In the case of liquid gas inside a float, I would open the hole up and power wash the inside of the float with brake cleaner to both chase out any residual fuel and crud particles. Brake cleaner evaporates quickly and leaves no residue.

 

[gggGary]

Try to trust me here on floats.
The test is HOT water; bubbles = fail.
I have tried soldering floats. Pete; I did blow one but I think it was just hot air, I'm guessing if it doesn't blow up it's prolly because you didn't seal ALL the leaks
I long ago gave up on float fix'n, If I am into a carb with brass floats I'm putting in new, I HATE a second trip in.No matter how good the cleaning fresh gas and use always seems to find some varnish to fuggle orifices. Sometimes seating and resetting idle mix screws helps.
And sometimes you just have to go back in. BS38s let you at mains AND pilots by removing the float bowls. A couple hundred miles, maybe with seafoam or techron might help.
650central link above, sells OEM IE genuine Mikuni floats. Every time I open clean and inspect a set of carbs with original floats under a magnifying glass I see stress cracks all around the float, you just can't win with repairs.

 

[mrtwowheel]

I've soldered many holes in Rochester 2 barrel floats, no explosions. Small holes were done with a soldering iron.

 

[MaxPete]

Hmmmm....well, ok then. I am going to be an optimist and hope that the new OEM float valves & seats will do it. I’ll also check for leaks and replace if necessary.
Dammit.

 

[YamadudeXS650C]

Consider my brass float repair with Seal-All:

http://www.xs650.com/threads/long-term-test-of-seal-all-for-carb-floats-update.50671/

 

[YamadudeXS650C]

To get all the gas out of a brass float, set it in the sun until it all evaporates out. A hair dryer will do the same job.

 

[nj1639]

The classic float repair was the Christmas light soldered to the float tang......where's that pic....

 

[79XStLouis]

Try to trust me here on floats.
The test is HOT water; bubbles = fail.
I have tried soldering floats. Pete; I did blow one but I think it was just hot air, I'm guessing if it doesn't blow up it's prolly because you didn't seal ALL the leaks
I long ago gave up on float fix'n, If I am into a carb with brass floats I'm putting in new, I HATE a second trip in.No matter how good the cleaning fresh gas and use always seems to find some varnish to fuggle orifices. Sometimes seating and resetting idle mix screws helps.
And sometimes you just have to go back in. BS38s let you at mains AND pilots by removing the float bowls. A couple hundred miles, maybe with seafoam or techron might help.
650central link above, sells OEM IE genuine Mikuni floats. Every time I open clean and inspect a set of carbs with original floats under a magnifying glass I see stress cracks all around the float, you just can't win with repairs.

Roger that, thanks for the good advice. New floats and another going-over to find an obstruction. Does it make sense to you...if a float was sinking it would stall the engine at idle and cause a popping in the exhaust from too much fuel getting by? AlI have is time now anyway.

 

[mrtwowheel]

To check a float that just came out of a carburetor with gas in it, shake the float, if there is gas in it you will know from shaking it. Then submerge it and look for bubbles as gggGary says. Leave it weighted down in the water for an hour or more and take it out and shake it.

Scott

 

[gggGary]

Should redo this it's a bit blurry

from this thread http://www.xs650.com/threads/carb-flooding-need-advice-following-the-guide.27306

Is it a leaky float causing your problem? We don't know. IMHO when working on old carbs there are about 40 things that COULD be the problem. After a few years of chasing my tail doing carb work I tend towards the replace known problem items, that still leaves plenty of troubleshooting to do.
kind of a reminder; many "carb" problems are found in the ignition and valve, cam chain settings. I also always replace float valves and seats. 'Bout all we can do is test and eliminate likely suspects in a methodical order 'til it behaves.
I usually fall into the cheap old bike is a "good deal" trap. But the true "good deal" is a well sorted, maintained, rust free older bike for about $2000 Yeah me neither LOL

 

[MaxPete]

Thanks Gary - even blurry, it is informative.

You know, when I finally got Lucille running in July 2016, I was so elated and amazed and she got better and better each day it seemed. I put more than 3500 miles on her with nary a burp. Then, in the late summer, a few weeks (and about 600 miles) after installing a PAMCO system, she suddenly started running extremely poorly and then simply quit altogether. After a fair bit of fiddling, including a carb clean, she refused to start. In desperation, I installed an old set of spark plugs and instantly, she was back.

Then, two days later, the pissing float bowl thing started.

It’s like she’s haunted.

...but I’ll get there.

Pete