Should I Be Worried? (Pilot Jet)

[RadMax]

So I’ve been having some carb trouble - I think I’ve finally got it sorted out, ridiculously high idle, replaced the diaphragms/slides - and I took my carbs apart yesterday... You know that rubber piece that goes in under the pilot jet? Well after I drained my carb, it was all swollen. Why is that, is that normal, and what is that piece even for? Could the swelling be ethanol-related? Of course I don’t use anything like ethanol/E85, I run dino juice, but you know how our gasoline “may contain up to 10% ethanol” these days?

I have a 2000 Kawasaki KE100 (it’s a two-stroke, ethanol eats two-stroke oil) too, so don’t even get me started on ethanol... But what do you think it is? Also, what octane do you guys use? Correct me if I’m wrong, but I think I’ve heard the XS650 has a fairly “modest” 8.4:1 compression ratio? I’m a 1980 Special if there’s any difference?

 

[grizld1]

Are you referring to the plug that seals the bottom of the pilot jet casting in BS34 carbs? If so I've never seen or heard of 10% ethanol causing it to swell. Nearly all the fuel we've been able to get here in Illinois has been 10% ethanol for nearly 30 years, and OE rubber carb parts have been proven resistant. Maybe the PO installed some Brand X aftermarket bits--there's some nasty stuff out there. If you look carefully at the passages in the PJ casting you'll see why the plug is there. To protect your 2-stroke, add a bit of marine formula Stabil; it's done a fine job of protecting my chain saw and brush cutter motors over the years. I think that tip came from bluebikerblan--haven't heard from him in a while, hope he's OK.

 

[Jim]

I've got 2 sets of BS34's. Neither shows any signs of swelling on those plugs. Like Grizld sez, I'd suspect they're cheap aftermarkets. They're there to seal the pilot circuit... so a little swelling won't hurt anything as long as they're not breaking down. If anything, they'll seal tighter.

Happy birthday Dick.

 

[5twins]

Yes, I've never found them swelled, just rather weathered and ratty looking. I have some aftermarket replacements but haven't tried them yet. Hopefully they will be OK because they are supposedly Viton rubber.

 

[gggGary]

Not common but I've seen a couple ballooned like a roasted marshmallow rubber plugs. My guess has been some sort of "chemical tuneup" has been tried by a PO.