Mikuni (xj550) pilot jet issues

Has anyone noticed any issues with the Mikuni pilot jets (in particular, the BS28 carbs on the 550) clogging up more often than usual?

I have an inline filter, not a bit of rust in the tank... Bowls look pristine (no slag floating around), but.... I keep having to remove and clean the pilots once in a while. They seem to oxidize right at the tip, and lose about 50% flow.

The tank gets filled at the same place as the other bike, but the Seca never has this issue. Granted, I don't put nearly as many miles on the 550, but it does not sit all the time either. I'm starting to wonder if the pilots are made of sub-standard quality brass. The previous owner had this issue when the bike sat over the winter, even with the bowls completely drained.

Maybe I should just get new pilots? *shrug*

 

I have the same issue with my 700. Nice clean tank and fuel filter. I guess it is the small size of the jet. It gets clogged easily. I don't have that problem with either of the 1100's. The pilot jets in those are prety big and don't get clogged as easily.

 

I have noticed the same thing but I think I had some varnish I wasn't quite reaching during my normal cleanings and it was making its way to the jets. I would recommend a super good cleaning and replacing the float bowl gaskets. I think the cardboard type float bowl gaskets, that I kept trying to resave, retain some of that varnish and when you get fuel flowing through the bowls again, it just moves from the gaskets and winds up taking residence in the jets.

Also, since the bike does sit around some, I would make it a habit to start putting some fuel stabilizer in with the gas.

 

Yeah, I usually see a bit of crud in the bowls when I take them off, but this time they were pretty clean... The stuff in the jets looked more like oxidation, or a mineral deposit of some sort. Carb cleaner won't touch it... I ran a piece of a guitar string through the jets to clean them out. The gaskets are not very old, so they should be ok, but I'll check them tomorrow just to be sure.

 

Very likely could be the fuel you are using (ethanol blend?) which probably evaporates quickly in the bowls leaving gummy deposits on the jets. The passages on the pilots (which you know, having cleaned them) are notoriously small. You might try running Sea Foam in your fuel, starting the bike every 2-3 days to keep fuel level fresh & full, going up one size on the pilot, or a combination of al of the above.

 

Be sure it isn't just a Bogus Filter. I had an Inline Filter on the Bike that "Looked Clean" ... but, I couldn't blow the gas in it ... out.