First Start on 77 Project Bike

[CYBORG]

speculation often leads to answers

[dontwantapickle]

Speculating here is all I'm doing.
Kinda tough to diagnose an electrical issue with pictures.

[leonardhcross]

After chasing ignition issues for a couple of days, I re-focused on my carbs. I had re-built the carbs and had cleaned and flushed the gas tank. I had also flushed the fuel pump and installed a new fuel filter. Here is what I found when I re-opened my carbs. Does this explain carbs 1 and 2 not firing? I don't know but clearly, I need to do a better job of cleaning and sealing my gas tank. https://www.youtube.com/watch?v=yk3hEHX ... XY&index=1

[Fred Camper]

Seems like the fuel filter should have prevented that build up. Strange.

[leonardhcross]

Fred. Thanks for the feedback. The yellow dust is so fine as you can see on my finger. However, I removed the tank and swished in some clean fuel. I was surprised at the amount of rust residue I trapped when I filtered that through a paint filter. It is also interesting to note that, even with this yellow coating, carbs 3 and 4 seemed to be operating fine.

[leonardhcross]

Hmmm? As I recall, I pre-filled the carbs with 180cc's of gas from my gas can and then the carbs sat for a couple of weeks before I tried starting. I think I'll drain that can into a clear container to see if that has somehow become contaminated.

[gltriker]

20250828_161213.jpg

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[leonardhcross]

Float bowl stained and dusty from gas .jpeg

It is always my hope that sharing my trials and errors might help some other week-end wrencher. I believe that I have uncovered the source of the yellow dust and staining inside my carbs. As for whether or not this helps with cylinders #1 and #2 not firing, we'll see. One thing at a time. Previously, I posted a brief video showing a coating of yellow powder on the floats and other internals. Nobody came forward with an explanation. So, today, I dug in a bit and believe that I have a reasonable explanation. I will add a couple of photos and a brief video at the end. One photo shows the color of the gas that I drained from my gas tank, (bright orange). That is followed by the same container with fresh gas in it, (bright yellow). A third picture shows the fuel gage sending unit which has been suspended inside this orange gas for a month or two. I have also included a copy of the float bowl with dusty, yellow powder. Here's what I think I have done....another "rookie" mistake. In the process of cleaning my gas tank and trying to open up rusted closed internal fuel lines, I used copious amounts of PB Blaster. At the same time, I was agitating the inside of the tank with nuts and bolts and flushing the tank with gas regularly. Each time I flushed the tank, I strained the cleaning gas through a fine filter and re-used the gas. I didn't notice that, as I used the gas over and over, it was becoming orange. In the end, I was satisfied with the cleaning as no new sediment was showing up in the straining filter. I gave the tank a last flush with the now orange gas and then fogged the inside heavily to seal the metal and prevent new rust. A few days later, I installed the tank and added a few gallons of fresh gas. I believe that the inside of the tank was still pretty contaminated with orange gas as well as fogging oil. As the carbs filled with this now bright orange gas, the dissolved PB Blaster must have settled out of the gas and adhered to the inside of the carbs. You can see from the images that the carbs and the sending unit were not just coated with a very fine dust, they were also heavily stained. I am concluding that an excess amount of PB Blaster contaminated the gas and settled out of the solution.

IMG_6008.jpeg

IMG_6003.jpeg

Sending unit dusty and stained from tank gas.jpeg

[leonardhcross]

Sorry, I tried but could not attach a short video.

[Track T 2411]

Seems to make sense. I only use carb cleaner or brake cleaner with fuel related issues. Carb cleaner can leave residue but it's formulated to break up fuel gunk. Brake cleaner leaves no residue, and rinses away the loosened gunk. My 2 cents...

[gltriker]

Float bowl stained and dusty from gas .jpeg It is always my hope that sharing my trials and errors might help some other week-end wrencher.

Looks as though the float bowl contents of "gasoline", as witnessed by the level of contamination accumulated on the sides of the float, itself, was full similar to a properly adjusted float level would have been.
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The float valve seat filter screens were clearly overwhelmed with the micro fine particles

Respectfully speaking to the diagnosis Len,
Unfortunately, this could be a lesson for folks that believe a new fuel filter, alone will protect their expensive, professionally rebuilt carburetors ($500+), from an internally rust contaminated fuel tank.

[leonardhcross]

Good morning Cliff. Thanks for your input. I suspect that I would not have noticed the orange tint inside of Cedric's float level sights. It was not until I saw the large, clear containers side-by-side that I realized how orange the tank gas was.