soot on the jets?

[oldskool]

hello all
this question is for the carb gurus or whoever know the answer....
so i was rejetting my carbs. changed the main and pilot on one carb and then moved to the next.  when i took the main jet out of the second carb, there was black stuff, im assuming soot, all over the threads of the jet and down in the hole where the jet screws into.  the "soot" wasn't present on the first carb and i expect that its not normal for it to be on just one.

anybody know why the soot is there?  

what is the best way to clean down in that hole where the jet goes, or should i not try to clean down in there.  i was going to use carb cleaner in a spray can to try to clean it out, but before i do anything that's going to cause more trouble later, i wanted to ask the pros here.

any suggestions or diagnosis of my carbs would be greatly appreciated.
thanks
oldskool

[cummuterguy]

could be the fuel lines breaking down internally, but I can't explain why only one carb would be affected :dunno:

[Rema1000]

Maybe a chunk of o-ring or hose went into one float bowl, where it sat until it turned to goo.

[The Buddha]

Its soot and not rust soot in the top 1/2 of the carb is normal, cos blow back from the engine gets through the choke mechanism when open and gets in the tops ... 90% of soot will actually get sucked back in ... leaving 10% to collect ... mostly harmless. Rust on the other hand will tend to go to the side of gravity and if the bike was on the side stand ... that = left carb, and it will end up getting more of it, and therefore left worse than right ... but of course if its the right ... no idea ...
Cool.
Srinath.

[Rema1000]

If soot is from blowback, then that could explain why only one side:  different intake valve clearances.

[oldskool]

100% positive its soot and not rust.  i believe it was the left side carb but i would have to check to be certain.

when i was draining the fuel lines i noticed that the gasoline that came out of the lines was saturated with a black "sooty" substance. i figured it came from the rubber fuel line that someone else had replaced, although there is a fuel filter in that line, so i can't explain it either.

any suggestions on how to clean the soot out?
will pressurized solvent parts cleaner work?..or should i not be spraying it down in the hole where the jet goes?

one more question, i remember a post about clear 'vinyl' fuel lines?  is that the correct type to buy to replace the black rubber lines?  is it the stuff that you can buy by the foot at lowes or do automotive stores carry it also.

thanks to all for your input
oldskool

[DerekNC]

As far as cleaning your carbs pull off as many rubber parts as you can. Remove the jets also. Then fill up a container with kerosene and soak your carbs overnight.  That's what I did to mine and they came out so clean you could drink out of them. :mrgreen:

Derek

[Rema1000]

I don't know; I'd look for polyvinyl fuel hose; Tygon is one popular brand, carried by many hardware stores.  It's yellow and usually marked "fuel/oil hose".  

There is clear fuel hose for sale at Home Depot, where they keep the lawnmower sparkplugs, etc.  Any dirt bike shop would have some; I got mine at a cycle shop.  

Auto parts stores are pretty worthless for low-pressure fuel hose.