vacuum petcock failing.

So on the FJ, as the XJ, there is a vacuum operated petcock. I have become aware of the fact that the vacuum seal on mine is starting to fail.

What I mean is this: when you suck on the vacuum port on the petcock, it is supposed to feel like sucking on a straw that all of a sudden gets blocked by a piece of paper, seals shut. On mine, you have to keep sucking to keep gas flowing--meaning there's an air leak.

Any ideas for rehabilitating that seal? This bike has massive gravity fed gas lines, and has a bit of a problem getting enough fuel into its system if everything isn't perfectly smooth. I started experiencing fuel starvation issues on my last long ride, where I did some long term high speed cruising. Keeping the throttle a little less open made the issues go away.

So, yeah, ideas?

 

Wrong way round mate. No vacuum means valve shut. Vacuum ie sucking opens the valve.

 

I'm aware. Think a little harder and you'll understand what I mean. Vacuum port seals, thus opening gas port.

 

Yeah, I see what you mean, but I'm not sure I understand the question. Is there no rebuild kit for that petcock? Or you could do what I did, buy a petcock at the junkyard, take off failing one "planning" to rebuild it. Then throw it in a tool box and forget about it because your "new" junk part is working fine. LOL.

Or did you want a super cheap way of fixing just one seal in the petcock? No idea, but maybe you could put some silicone on it or something. I wouldn't bother, if I took one apart, at that point might as well do full rebuild. Fitz has a write-up, showing what surfaces need polishing and everything.

Here ya go, a little hard to find since he never says "petcock" haha. http://xjbikes.com/Forums/viewtopic/t=25058.html

 

There is no rebuild kit. This bike happens to have the most expensive petcock Yamaha ever built--on the 86/87 FJ1200's, Yamaha tried an experiment with an 'electronic reserve' function, building in a solenoid with a plug coming off and going to a button in the fairing.

Cost for replacement: $250 new. One parts guy for the forum has gotten them down to like $175 somehow. The ONLY generic replacement option is like $135, and isn't vacuum operated... Which is a huge problem since you can't see/access the petcock while the fairing is put together.

So yes, just trying to figure out home repairs for my woes. Maybe finding some spare rubber and cutting a replacement gasket for the seal in question?

 

Maybe carefully take it apart, snap a couple of pics, and let's compare it to the rebuild kits for the vac-op petcocks that ARE available? Maybe a usable bit there?

I didn't use the word "petcock" in the title because it would get auto-censored.

 

I'll do that. Actually, it had a leak when I got it, so I filmed some video of the 'fix' as a how-to video. I'll try and get that edited here quickly so you can see the internals.