Carb question

[ME 109]

No, it isn't sudden, it's a "tipping point" in a long slow gradual process.

That's my point. Chuey has fuel pissing out, suddenly it appears. So how can a fuel soaked float cause a sudden leak?
It can't. The other side of the "tipping point" would be a weep, in both a static and dynamic situation.

I think the float's ability to pivot on the pin is compromised, affecting the needle, or something is preventing the needle from seating, ie junk protruding through the seat hole. Even a worn needle tip is most likely to produce a weep at first.

Come on already Chuey, have you blown compressed air through the fuel inlet passage from either direction?? That is from where the fuel line attaches to the carb, and upwards through the hole in the seat.

If a float becomes soaked in fuel, fuel evaporates when the float is removed and put on the bench. There is no residue to increase the weight of the float, unless the float has accumulated solids. Imo,

[Major Softie]

If a float becomes soaked in fuel, fuel evaporates when the float is removed and put on the bench. There is no residue to increase the weight of the float, unless the float has accumulated solids. Imo,

Even though that makes perfect logical sense, I believe you're wrong. I do no know exactly the process, but the floats gain weight, and the weight sticks. Otherwise, they all be like new again if you dried them out.

Edit: According to Snowbum, if left to dry, the floats WILL lighten considerably, although not back to stock weight, but this "drying" takes one to two MONTHS.

[Chuey]

I will take the carb body to work tomorrow where I can put compressed air through the fuel inlet. I have a brand new float assembly and a new "needle" and brand new official current BMW fuel line.

Truly, I can't say how "all of a sudden" this problem was. I do agree with Jeff that it seems it would not appear abruptly but it is possible that it did not do so but, over time, became noticeable. If I only rode one bike, that would be easier to ascertain but that is not the case.

I'll post here what the results are of the latest attempt. To sum up, there will be a blow out of the carb with some badass high pressure air. A new fuel line. New seat to hopefully seal very well against the jet. Brand new floats. I will try to remember to take the old and new floats to the shop to weigh them. I have some pretty cool antique scales that have been checked against digital laboratory scales of a friend's lab. I'm not sure about reading two grams difference, though.

Chuey

[Major Softie]

BTW, Chuey, Snowbum says new floats are 10 grams.

[Rob]

Since I quit owning airheads and quit smoking, I will send you my digital scale, Chuey. That thing is remarkable.

So, I take it your scale is a Lady Justice type? All you need, then is a 10, 5 and a few 1 gram weights!
AND NO SHEET!

[ME 109]

Chuey, the fuel passageway between the fuel inlet where the fuel line connects, and the needle seat, is quite a reasonable diametre. Use your compressed air from the seat side. Blowing backwards so to speak.
I once found a small crescent shaped piece of fuel line poking through the seat, preventing the needle from seating.
The crescent shaped piece of fuel line was from the id of one of the cut ends of fuel line. It came from the fuel tap, or the crossover T piece, or the connection at the carb. That's five different places on one side of the tank.
You'll sort it.

[barryh]

I'm puzzled by Snowbums figure of 10 grams. My new floats from Motobins weighed 12.5 grams on calibrated lab scales the type where you close a window to prevent a draft affecting the reading. I'm in no doubt that these scales were accurate to better than 0.1 gram. A quick search turns up several instances of new floats being found to weigh 12 grams and one reference that Bing say they should be 10 grams but no evidence that anyone actually weighed them at 10 grams. Has anyone else weighed new floats accurately ?

[Rob]

I don't know how accurate it is, as I have no enclosure ( ), but I just got 12.6 on one that I have left over. (hi Brad!)

[Chuey]

I just checked in to say that I weighed the new floats I just got and they weigh 10grams. The old ones weigh 14 grams. That said, the scale I used is probably not optimum for those low weights. I am encouraged that there is a repeatable difference and the new ones are surely a tad lighter than the older ones.

Also, I took the carb to the shop and shot air through the openings. I hope to put that sucker back together tomorrow after my bike ride with Bride of Chuey. (Maiden ride on a newly refurbished 1971 Raleigh International - has the patented Chuey modifications to make it ride like modern bikes but look tons more charming - actually, better than many new bikes [for me].)

I will report the results.....of the carburetor work, not the bike ride.

Chuey

[ME 109]

I will report the results.....of the carburetor work, not the bike ride.

Chuey

Ah, planning on falling off in the long grass, eh! You can show a photo of your 1971 Raleigh International, but that's all.