1998 Steamer, Keihin carbs all messed up +fuel in oil.

[Persson]

My bike has been running funny. Jerking and sputtering, uneven idle and backfires sometimes. In short, not well at all.

Last time I went for a ride it started to act up really bad. At one point it even died on me when shifting down at an intersection.
I made it back home and it ran poorly all the way.

Yesterday I went out to the garage to take a look.
I started the bike up, and it sounded awful! Black smoke came out of the exhaust, it ran extremely uneven and the sound was like if it was gasping for air, almost like you would try to drown it in water.

I have experienced a car with the same behaviour, so I did what I was taught and checked the oil first. The dipstick was wet up to the lid and rank of gasoline. The crankcase was flooded with fuel.

Obviously one or more carbs have leaked fuel down inte the crankcase vent.
-This is odd, since I cleaned out the carbs a month ago at the same time  when I replaced the airfilter.
The floaters moved freely and the bowls were clean and nice. The floater needles looked ok as well.


Besides, the gashandle was completely stuck and could not be moved.
I dismantled the gaswire from the handle to see if the handle was jammed, but it was ok, and so was the wire. I traced the problem down to the carburettor.

So I removed the brand new airfilter/box and found lots of silicone chunks and debries loose in the airbox.

When I removed the airfilter, I found the carburettors all gooed up by melted rubber.
The silicone lining in the airfilter is all dissolved
However, there is absolutely no scent of burned rubber.
Even though I admit it looks like there´s been a fire, I doubt it.

What the hell happened here?  The intake rubber feel spongy at the touch, like it has been dissolved by acid, and not crusty or sooty like one would assume it would be if it had burned.

The carbs are in such a state that I am not even sure they can be saved.
I´ll try to clean them out and replace what ever parts avaiable on the market, but hopes are low at the moment...

[John Stenhouse]

Sure looks like a fire

[Sin_Tiger]

Its there a lot of e ethanol in the petrol where you see? Help us out to help you by updating you profile please.

[Persson]

Its there a lot of e ethanol in the petrol where you see? Help us out to help you by updating you profile please.

Hi Sin, thanks for the input!

I live in Sweden, and our gasoline is European standard I guess.
But I do not think that is an issue. Besides, these rubber parts must be manufactured to resist gasoline and such.

Otherwise I would not be the only one with this problem.

[Rocinante]

My guess, stuck float causing floading which for some reason resulted in fire.

I´ve had stuck floats two times, both after I had the carbs off and dismantled. My guess is the needle gets stuck in the process. First time it loosened by itself, the second time I had the carbs apart again. The float wasn´t stuck when I opened the carb, so it probably loosened its grip in the process.

Find a replacement carburettor and buy a new air box, sounds to me like the way to go.

[Sin_Tiger]

Even though there's no burning smell I still think its burned like you already guessed, just a chemical burn. The trouble is figuring out which chemical, which is why I asked about the ethanol.

I seem to remember reading somewhere that Sweden has E85?

I'm wondering now if its been a bit more complex with more than one chemical, acid? Alkali? Not much more help I'm afraid mate.

[Persson]

My guess, stuck float causing floading which for some reason resulted in fire.

I´ve had stuck floats two times, both after I had the carbs off and dismantled. My guess is the needle gets stuck in the process. First time it loosened by itself, the second time I had the carbs apart again. The float wasn´t stuck when I opened the carb, so it probably loosened its grip in the process.

Find a replacement carburettor and buy a new air box, sounds to me like the way to go.

-Yes that is my guess aswell, it was probably my fiddeling that caused the carb to flood in the first place since it was ok before I took it apart.

Is there anyway to check that the assembly was correct after a teardown?
I.E can I make sure the bowl keeps tight before putting the carbs back into the bike?


I have begun cleaning out carb 1, the dirtiest one. Removed all plastic and rubber parts and cleaned the housing with thinner and a toothbrush. (The toothbrush has some siliconedetails, or should I say had, as they dissolved in the thinner.) But the carb is actually coming out a lot cleaner than I was hoping for.

Still, there are small holes and spaces that I can not get to with a brush, so a ultrasonic will be needed.
I located an ultrasonic cleaner with a capacity of 2 Litres at a dealer for just about 100€ (145$) I´ve been looking at one of those anyways, so now is probably a good time to get one.

Thanks for the input Rocinante.

[Persson]

Even though there's no burning smell I still think its burned like you already guessed, just a chemical burn. The trouble is figuring out which chemical, which is why I asked about the ethanol.

I seem to remember reading somewhere that Sweden has E85?

I'm wondering now if its been a bit more complex with more than one chemical, acid? Alkali? Not much more help I'm afraid mate.

Yep, that is true, we do have E85 at the gas station if one wants.
Some people here run 70% gas and 30% E85, to boost combustion.
But I do not, and especially not in my bikes.

You are probably on to something there, I repaired the snorkel-fitted airbox with chemical resistant silicone glue, the best allround glue I know of, as it had let go in the joint between the two halves.
And that glue had also turned into molecules aswell...

More info coming...

Thanks man!

[Bixxer Bob]

The lack of a burning smell is odd, because the pics point to backfiring through the number 3 carb lighting the leaking fuel and melting the rubber which then affected number 2.  

On the other hand, I've seen chemical burning of brass before but not aluminium so can't comment on that hypothesis.  The brass burn was a complete surprise; I'd turned up and polished a pair of brass candlesticks while the chippys made a wooden presentation case lined with green beize.  The beize was glued in with PVA. When we opened the box the next day to show off our work prior to the presentation the candlesticks looked about a hundred years old - all blackened and pitted.  We put it down to the acid fumes from the PVA and did some very hurried repolishing.  But to come tothe point, they looked the same as that no3 carb.

[Persson]

The lack of a burning smell is odd, because the pics point to backfiring through the number 3 carb lighting the leaking fuel and melting the rubber which then affected number 2.  

On the other hand, I've seen chemical burning of brass before but not aluminium so can't comment on that hypothesis.  The brass burn was a complete surprise; I'd turned up and polished a pair of brass candlesticks while the chippys made a wooden presentation case lined with green beize.  The beize was glued in with PVA. When we opened the box the next day to show off our work prior to the presentation the candlesticks looked about a hundred years old - all blackened and pitted.  We put it down to the acid fumes from the PVA and did some very hurried repolishing.  But to come tothe point, they looked the same as that no3 carb.

That was my first thought aswell. A backfire flame through one of the carbs that ignited the fumes/fuel in the airfilter and intake tunnel.
(If that would have been the case, the whole bike could have been torched...)
But there´s no crust on the intake rubber boots, no sign of soot on the inside walls of the airbox. There was no smoke or "poof" from the carb area.
I´ve seen carbs backfire on cars and bikes, and you get that special reversed "SCWOO-OOP" sound, and a thin sooty residue on the carbs intake.

The goo in my carb/s is somewhat greasy and oily. Not that dry charred coal-like residue. I´ve never seen anything like it. And it only smell like a carb normally does. That mechanical and gasoline whiff.

..Very weird..

[Bixxer Bob]

Here's a really wild shot then, how's your battery and charging circuit?  And where does your battery vent to?  Battery acid would do that, and overcharging would lead to the battery vomitting acid.......

Like I said, a really wild shot........ :lol:

[Persson]

Here's a really wild shot then, how's your battery and charging circuit?  And where does your battery vent to?  Battery acid would do that, and overcharging would lead to the battery vomitting acid.......

Like I said, a really wild shot........ :lol:

Hey Bix,

Wild it may be, but even shots in the dark are better than nothing.
However, I run a sealed gel-battery, so there is no vent...

Thanks man,
/P

[Mustang]

when you had the carbs out last did you use anything on them to 'lubricate' the rubbers to make the boots easier to go back on ?
that would be my guess if fire is ruled out ..................something definitely attacked the rubber still looks a lot like fire in the pics though especially the grunge on #3 slide

[PompeyLad]

Any smell of acetone in there? I have seen rubber do that when exposed to acetone. E-85would more likely just dry out the seals etc. Pissed any body off lately?  

[Persson]

when you had the carbs out last did you use anything on them to 'lubricate' the rubbers to make the boots easier to go back on ?
that would be my guess if fire is ruled out ..................something definitely attacked the rubber still looks a lot like fire in the pics though especially the grunge on #3 slide

Hi Mustang,

Nope, they went on dry.
-Might have used some saliva, but I brush my tooth and haven´t been on the heavy stuff for a long time now :D  :D


But I think I might have a clue as to what happened.

I´m leaning more and more towards some kind of fire as You all say.
After all, -if it looks like a cat and meows like a cat...

But! (and there´s a big butt) I´m thinking in lines of:
Let´s say they did burn.
-How "big" a fire or thermal development must it not have been to cause the rubbers to look like this?
If You would lick these rubber with a flame, how long would You have to go at it before they look like this?
And if You did, would there not be a massive smoke development?
Would these rubbers not be smelling like "holy smoke", in fact the whole bike would probably smell like shit.

-Unless the smoke was sucked into the combustion chamber and on through the exhaust pipes.

I have to move on, I have to let this go! :twisted:  :twisted:  :twisted:


Is there anyone here that can guide me to a "safe" and reliable way to assebly the carbs back again?
I´m hoping to get these carbs back in order after all, but obviously I did something wrong the last time I put these back together.

Is there anyway I can check the function of the carbs when they are out of the bike?