82 XJ750 Maxim fuel petcock leak

Ok, new issue to work out. I'm hoping to lean on the knowledge of this group again. Sorry for the long post.

I've noticed a fuel smell in my garage the past couple of weeks but I thought it was my mower gas tank. The bike started and ran like normal so I thought nothing of it.

A couple of days ago I noticed a couple of drips of fluid on the ground under the bike. I took it out to start it and it took a few crank attempts to get it going (choke completely off). The bike had always had to have choke to start. After it was up and running it seemed normal.

Today I noticed the same issues. It took about 6-8 crank attempts to start the bike. (I'm assuming clearing out the excess fuel, flooded condition?) After it started it ran normally. took it to the store for some stabil. It's getting cold out!

When I took a closer look I noticed some fuel accumulating on the bottom screw of the petcock (arrows in pics) and dripping onto the boot below. I also noticed some fuel at the bottom of the airbox.

I'm assuming I'm going to have to get a new petcock because they don't have a rebuild kit to buy?

Also, after searching the forums I'm seeing that I may have a separate issue in the carbs themselves. The fuel goes into the back of the carbs and overflows the bowls into the airbox? From the other posts I looked at the oil level and it hasn't risen so I have that going for me at least.

So I guess problem #1 is the petcock. Any recommendations on the best place to source a replacement?
Problem #2 is the fuel leaking from the airbox. Am I looking at a complete rebuild of the carbs? I'm mechanically inclined but have zero experience on carbs. I have no idea where to start on this one.

And last, I'm thinking about draining the tank and carbs (screw on the bottom?) Normally I just add stabil and call it good for the winter but with the leak I can't have my garage smelling like fuel since it seeps into the house. Will having them empty for awhile cause any issues?

Sorry for the long post, I hope it makes a little sense. And as always, thanks for the assistance.

 

petcock leaking is 1 issue which you can resolve by rebuilding the petcock. eventhough they are rebuildable some are just to crapy to rebuild.

fulel in the airbox is more likely from needle valve issues they control the flow of fuel into the carb bowls . even if you left the petcock on prime no fuel should be flowing into the carbs.

you can drain the tank but you should use fogging spray to prevent rust.

chacal aka Len from www.xj4ever.com sells new petcocks and rebuildkits. there is a link on this site on hoew to rebuild.

Rebuilding the Yamaha Vacuum Fuel Valve w/pics


we also have a link on rebuilding the carbs is looks hard but is easy

IN THE CHURCH OF CLEAN

you may just have to replace the needle valve assemblies

many peopls drain the carbs for the winter

 

Follow the links XJ550H posted , as long as your petcock is not pitted inside you should be able to rebuild , takes about 20 minutes easy peasy . I would recommend keeping the vacuum petcock ,the cheap aftermarket peacocks work okay BUT if you forget to shut off after riding , you can end up with a crankcase full of oil.

 

Thanks for the quick replies. I shot Len an email.

Petcock issue first and then I will tackle the carbs. Are you able to purchase just the needle valve assemblies or do you have to purchase an entire kit?

 

You can get just the float valves but if your carbs haven't been to church, ever, I strongly recommend getting a deluxe rebuild kit as it includes everything you need to do a complete tear down. You wont be disappointed with the service from xj4ever. Oh and the parts are spot on too...

 

you can just get the needles or the needles and seats. start there and you can start by cleaning out the jet passages with spray cleaner . your carbs have been working ok so you only have a needle problem to tend to. you will have to reset the float height and fuel level when you change the needles
measure your float height and the old needle length and new needle lenght compensate float height based on the differance , then start the wet set.

if when you open up the carbs they are all gunky then make the move to go to church

 

*Update*

As I was draining the tank from the fuel line just aft of the petcock, the "ON" and "Res" positions worked as advertised and shut off fuel flow when selected. Fuel would only drain when in "Pri" mode. The petcock working correctly was an unexpected surprise.

When I was looking for my flat screwdriver I forgot that I didn't own one since I use one at work all the time. You just have to make due with what you have lol.



After getting the petcock off I noticed that the screw gaskets were hard/brittle and the petcock to fuel tank o-ring wasn't in the best of shape


My belief is this will be the most likely location for the leak. The only other possibility that I can see is the selector switch o-ring. It didn't look too horrible though.



I took everything else apart to scope it out since it was off the bike. The plunger seat looked pretty good actually



And the plunger o-ring didn't look horrible, just a little deformed. The diaphragm didn't look bad either.





Not too bad of a job so far.

Anyway, I plan on ordering the parts from Len shortly to get this taken care of. I apologize for the large photos. I am not sure of the etiquette on if we should post the full size or just thumbnails, or just leave everything to the end where you can click at will.

Thanks for your input and help. Hopefully one day soon I will be knowledgeable enough to start pitching in on these posts.

 

*Update #2*

I ordered the standard rebuild kit, drain screw washer, and petcock to tank screw washers from Len (xjforever). He was amazing to work with! Always answered emails within 2 hours and I received the parts on Monday. I ordered Friday night!

Got everything back together today. No leaks and runs like a champ!

Thanks again for the information.

 

Guaranteed to get the right parts the first time around with Chacal.......XJ4ver