The carburetor is from a friends semi restored Yamaha 200. He has owned the bike several years, complained of tuning issues, but has never had the carburetors apart.
I told him I'd like to help rebuild them. I went to his home and we removed them from the engine. We disassembled both, documenting the jet sizes and needle clip locations as we moved along.
During the cleaning, air blowing process, I realized that one of the carburetors pilot jet passage was clogged. We sprayed carb cleaner and air repeatedly, nothing. Could not get it to clear.
This went on for two or three hours until we called it a night.
This morning he called, said the pilot jet would only grab the threads and turn down less than one revolution. I had him bring it over to my home and sure enough, it was as he said.
It must have come out that way and we just didn't recognize it at the time. We grabbed a tap from my set and tried to chase the threads. It got tough once we hit the spot the pilot hung up at.
I forced the tap deeper, just a 1/2 turn and backed it out. Some metal, but nothing too scary, so we cleaned again and continued on with the tap.
It was rather tight and I didn't want to apply more pressure than I thought the jet would need to sit snug in the threads, rather than strip the carb and force him to find a replacement.
It was running before we started and I didn't want to be the reason it would not be running when we finished.
The passage would clear, then clog and this went on for a few hours. You could see something down there, but even with the magnifying light, it was tough to make out what the blockage was.
I continued with the tap, 1/2 turn in then back out, cleaning as we went, removing any threads that broke free. I got to almost the depth of the pilot which we had marked on the tap and then without warning,
something fell out onto the paper towel on my workbench. It was the nose, or seat end of an old pilot jet.
It was acting like a ball valve down there, opening and closing the passage as it rotated at the bottom of the threads every time we moved the housing.
Still noticing something else was down there, we picked and picked and removed the remains of the shaft of an old pilot jet as well.
With freshly chased threads and a clear passage, we had won with patience and venturing into the unknown. We installed a new Mikuni jet and it bottomed to the seat nice and snug.
Trying to figure out how it got there, we came to the conclusion, that a pilot must have been stuck at some point in the bikes life and someone drilled it out for removal. Except they never removed it.
We imagined a small drill bit was used, then larger and larger, which spread the thin pilot wall into the passage below the threads.
Once a drill bit wider than the narrow part of the pilot was met, it cut off the seat and left it buried below the portion spread into the passage.
They must have gotten enough bite, the one revolution we had on removal, to install a new pilot jet and called it good.
Another one of those stories of not knowing what you will uncover from a previously owned motorcycle.
It was quite a bonding session, as our trust in each other grew as we not only uncovered, but solved an issue neither of us had encountered before.
We were both glad it ended on a positive note. Both of us enjoyed the satisfaction after hours of not understanding a blockage we could not clear.
Not the most exciting or informing story, but I thought I'd share a part of my weekend, Not Triple Related.
I'm working nights this week, so typing this helped keep me awake to prepare for the upcoming late schedule.
I just met John a few months ago. We had the two stroke thing in common and it grew from there.
We each met each others spouses, kids and dogs, during this two day dilemma of a blocked pilot jet passage.
It made for an enjoyable weekend with a new friend and meeting each others families.
Here's a photo of the pieces we removed and if you look closely, you can see the pilot jets holes in the largest piece as well as the nose of the old pilot that blocked the passage.
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