Fuel Petcock issues

I just put the K & L petcock rebuilt kit on and now the fuel valve will leak. I know the o ring is a little different on the vacuum side and could cause some leakage. What can I do to solve the leak?

We have had three days of rain in MN so now is a good time to fix it.

 

I put the rebuild kit on that chacal sells. It also leaked a little right after I put it on. I went ahead and put the tank and everything together and rode, figuring that even if the petcock leaked a little, my float needles would handle it as they didn't seem to have any problems. I checked for the bubble in my oil level often also and didn't see any increase (from gas leaking into the carbs and working it's way into the crankcase).

A couple of weeks later (yesterday) I had to take the tank off to get the carbs off and rejet. I was dreading it because of the leaky vacuum oring. Turns out, it seats perfectly, and hasn't leaked a drop in over a day.

 

There's a heap of stuff on this forums about Petcock rebuilds.

Remember to add your bike details to your signature - it helps.

You can read about my sorry attempts here: http://www.xjbikes.com/Forums/viewtopic/t=23203.html

This is worth a read: http://xjbikes.com/Forums/viewtopic/p=82713.html#82713

As is: http://www.maxim-x.com/petcock.html

If I had to do it again I would first ensure the seat of the O-ring in the vacuum side is very clean. If that doesn't work then try the tap method mentioned in the post above. I had gone so overboard with this that the fuel would only come through on PRI. After a few days of riding though I tested again and it now works without leaking. Sometimes the God's smile on you

 

In one of my previous forums Hot bike fast idle I talked about the bike idling at 3000 when hot. Could this have anything to do with the O-ring not seating perfectly?

 

no, but what will do it is not changing the pilot if you changed the main (if you put pods and/or exhaust).

 

There are a few tricks to successfully rebuilding Yamaha petcocks, I've got the how-to article nearly done.

 

I think I found the problem with the fast idle. I think that there are cracks around the bronze pins on two of the intake boots. I sprayed WD40 on one and it bubbled and I think raised the idle a little. Could a crack around pins cause the fast idle? There are no cracks around the rest of the boots just around the pins.

I started having the problem around the same time I changed the boots. I bought them off eBay because they were not as cracked as the old ones on my bike. Can I spray silicone around the pins to seal the leak?

I put a generic shut off valve in to solve the leaky petcock.

 

RVT sealant around the vacuum ports and let it cure fully before you start it.

 

Yes, the idle would be higher if the boots are allowing air to get sucked in through them. That would create a leaner condition, along with all the inherent problems associated with that. Iwould not use silicone to seal the leaks. I would use black rtv and seal the up good, or use liquid electrical tape.

Dave Fox

 

Leaner, I was hoper to get better gas mileage by sealing up these boots. The bike is only getting 31 miles per gallon. Granted I am driving on a hilly road too.

The bike will some what cutt out or hesitate around 4000. Boot problem to or just out of sync carbs?

 

I've done the fuel tap rebuild on mine, it didnt work properly, I had problems with carbs overflowing when using the kickstand.On the Maxim Website there is a great masterclass on all things petcock,the main point I thought is that most pattern diaphragms have a plunger that is slightly smaller than the stock item,therefore not making contact with the seat of the valve.
Problem is sorted by placing the diaphragm on a suitable socket ,14 mm with the plunger down and LIGHTLY tapping on the reverse side of the diaphragm, with another socket placed on top.This in effect makes the plunger longer,2mm being the correct amount. Also the spring can be lengthened to around 25mm,helping the plunger seat properley.Doing has this solved My petcock problems.