Topic: Carb Question

[Harper]

Hi Everybody,

I'm rebuilding the carbs on my CB750 K5. Carburetor 1 and 2 were nearly spotless, but 3 and 4 were completely gummed and scaled up. Is there a dangerous reason for this difference?


Thanks,

Harper

[Gordon]

I'm not sure what you mean by "dangerous reason". 

[Spanner 1]

Is this a trick question?!.... if the bike sat on it's side stand for a long period of time, carb 3 and 4 would drain into 2 and 1 and be exposed to air in the bowls causing oxidation and gas residue left behind which turns to gum ....my 2c.

[Harper]

Gordon: by "dangerous reason" I just meant "something to worry about." I know s&*t about all this, and am tryin to learn a lot. So sometimes I don't know how to ask anything more specific than "is something wrong." Haha, but you're right: "dangerous reason" is a pretty unclear way to ask that question.

Spanner 1: This must be it. The bike has no center stand so for years (the PO says he never cleaned the carbs and didn't know when they last had been cleaned before him) it was listing to the side. Thanks a lot!

[SHELLFISH]

Is this a trick question?!.... if the bike sat on it's side stand for a long period of time, carb 3 and 4 would drain into 2 and 1 and be exposed to air in the bowls causing oxidation and gas residue left behind which turns to gum ....my 2c.

Harper, I would not have expected that answer.
If the fuel is shut off then all carbs gas would evaporate at the same rate...wouldn't it?
Whatever fuel that was left in the lines after the petcock (not very much) would drip into the crabs equally and there is no way for carbs 3 & 4 to fuel carbs 1 & 2 I don't believe. I can understand how carb #2 will feed #1 and #4 will feed #3 to some extent. I will admit I have no knowledge of 750 carbs.

Funny though. I just opened the carbs on a 550 that had been sitting on it's side stand for 25 years. Carbs 1 & 2 are reasonably clean. #3 is not too bad and 4 is a little better than #3.

[Spanner 1]

I just opened ( well some months ago! ) carbs on a K8 750 that sat on it's side stand for years, outside mostly. Carb 1 and 2 were glazed with gas 'gum' and not oxidised, but 3 and 4 were not gummed but oxidised with a al. fur, bad ! Shows me that over time the gas at an angle in the bowls will back-up thru' the gas links and # 2 and 1 would be last to dry-up...may take months rather than weeks for all the gas to evaporate IMO. Also any condensation in the bowls would rise into 3 and 4.....who knows, my 2c.