MYSTERY Carb Deposits

[Paul S Wilcox]

Hi Folks,

Has anyone ever seen carb deposits like the ones in this photo?

I've rebuilt many carbs over the years but have never seen these chalky, yellowish powdery chunks of mystery crap.

History:
-- When I first tore down my carbs about four months ago, they had the usual brownish gum/varnish/gook we've all seen a million times. I cleaned everything with carb spray and ultrasonic (water + a few drops of Dawn) with great results.

-- I also flushed the tank and replaced the fuel filter.

-- The bike ran but had other problems, so it sat for 3 or 4 months, with fresh fuel + Sta-Bil + gas treatment.

-- Last week I had other carb troubles that required another teardown. That's when I found these tiny yellowish nuggets.

What the hell is this stuff? How did it form so quickly in just a few months?

Has anyone ever seen this?

Any theories?

One thing for sure is that I'm gonna re-flush the tank and add not one but two new fuel filters.

Thx!

Paul

 

[MaxMidnight]

Pure speculation but as it seems that the only change that you have made is adding the Sta-Bil + gas treatment then I'd suspect one or both are the culprits.

 

[Fire-medic]

Pure speculation but as it seems that the only change that you have made is adding the Sta-Bil + gas treatment then I'd suspect one or both are the culprits.

Hi Folks,

Has anyone ever seen carb deposits like the ones in this photo?

I've rebuilt many carbs over the years but have never seen these chalky, yellowish powdery chunks of mystery crap.

History:
-- When I first tore down my carbs about four months ago, they had the usual brownish gum/varnish/gook we've all seen a million times. I cleaned everything with carb spray and ultrasonic (water + a few drops of Dawn) with great results.

-- I also flushed the tank and replaced the fuel filter.

-- The bike ran but had other problems, so it sat for 3 or 4 months, with fresh fuel + Sta-Bil + gas treatment.

-- Last week I had other carb troubles that required another teardown. That's when I found these tiny yellowish nuggets.

What the hell is this stuff? How did it form so quickly in just a few months?

Has anyone ever seen this?

Any theories?

One thing for sure is that I'm gonna re-flush the tank and add not one but two new fuel filters.

Thx!View attachment 71545Paul

If one's good, two's better? Nah, one good one's fine.

That crud appears to be crystallized remains of whatever you had in-there, as M.M. said, so, gasoline, Sta-Bil, and possibly, water. Don't over-think this. Do as you said, another thorough carb cleaning, flush/scope the gas tank, and then fresh gas. I suggest that if you intend to leave the bike idle for > 2 weeks, drain the float bowls, it takes literally 5 minutes, and the float bowls cannot grow crystalline deposits when the bowl is empty. I suppose that if you really wanted-to, you could disconnect the gas line, and purge the gas in the tubing from the gas tank to the carb rack, into a receptacle, and study its quality, instead of just turning the key-on starting the gas pump, and re-filling the carburetor float bowls, once that you are ready to resume riding.

 

[Paul S Wilcox]

Thanks. All good ideas, to be sure.

Back in the days of manual petcocks (or even vacuum-actuated ones), you could turn off the gas a few blocks before returning home and, if you timed it right, could empty the float bowls completely as you coasted into the driveway. Not that I ever did that, but hey, I COULD'VE.

 

[02GF74]

But you could fit a switch to turn of the fuel pump to run the carbs dry.

I am not sure what you hope to achieve by fitting a second filter. If you fit it in line, then the second one isn't going to be adding much. It should see no debris ad the first one will have trapped it a d o ce first one is blocked, the second won't be getting any fuel so you've gained noting

I would advise against as the more joins there are, the more chance there is of a join failing, and since the fuel lines I'd under the seat, the last thing anyone wants is fuel pissing between their legs.

But if you insist, fit one filter but larger than the original, it does not solve the crud issue but means the filter will take longer to get blocked.

 

[Paul S Wilcox]

That makes perfect sense. I will stay calm and carry on with the other precautions.

Updates next week.

Thanks!