Yamaha Xj650 carb leaking gas

[Thedude]

So i got a 1982 yamaha xj650 from a coworker that was sitting for about a decade. last summer I worked on cleaning it up and went through the carbs and clean them out (more than once) and also synced the carbs. long story short I got the bike running and driving again but if the bike idles it will drip gas, while in motion it will not (obviously because gas is being constantly pulled through) but after it has been moving when it goes back to an idle it pours gas from the carbs. now i cleaned everything out and polished everything i could (I didn't polish the rubber on the float needles but the issue could still be from bad needles although they look alright). I cleaned the jets also and got all the gunk out of the carbs and made sure the floats are not stuck. now the gaskets on the carbs are in rough shape but a mechanic friend of mine said that wouldn't be and issue. I did replace the air filter with pod filters and did adjust everything to get a good idle. So I don't know what else to do.

 

[angus67]

Check float height

 

[TimeMachine]

Gaskets being in "rough shape" seems suspicious. Vacuum petcock equipped ? If so, also suspicious. Interesting though. Good Luck , RT

 

[Thedude]

It does it on both settings, vacuum and gravity. But when on gravity it spills more

 

[Paul Sutton]

Where exactly does the fuel leak from the carbs - Any pictures available?

Thank you.

 

[MaxPete]

If the leak turns out to be from the vacuum petcock, there may be a replacement available from MikesXS.

Check the petcock mounting screw spacing on your XJ tank and if it is 46mm, then look up the non-vacuum replacement petcock MikesXS p/n 20-0019.

Pete

 

[Thedude]

It leaks from the seam from the carb caps where I circled on the picture, not the hole. Sorry for the bad pic that bike is in storage right now I'm just planning ahead

 

[MaxPete]

Looks like the float bowl gasket. Check at Yamaha Parts online to get the p/n It's likely available new for just a few bucks.

 

[TimeMachine]

Agree, back to the "rough shape" gaskets. Drain the bowls a couple times, cross fingers that tank debris is causing needle and seat to not shut off fuel flow ? After that its float level etc... Good Luck tho ,RT

 

[Thedude]

Ok I'll start with that thanks guys!

 

[MaxPete]

Just one more thing Dude: those screws holding the float bowls on the carbs will likely be VERY tight so you must use the correct screwdriver on them.

The head may look like a regular North American Philips head - but it isn't.

Those screws, and in fact everything on every Japanese vehicle (car or bike) that is not either a socket head cap screw (Allen key) or a hex head bolt - is actually a JIS (Japan Industrial Standard) head fastener. You really should get a set of JIS screwdrivers to use on those screws. A set of these JIS tools (there are about 4 sizes in the set I think) are easily available on the web at reasonable cost.

The best brand of JIS driver is Vessel - and they are widely available in a fetching blue-green colour. They are very nicely made - every bit as good as Snap-On but they fit the screws on our bikes perfectly - while Philips simply do not. I clipped the advert that appears below off Amazon.com just now to give you an idea.

The alternative is to use a Philips screwdriver which will not quite fit - and risk stripping the screws.

Pete

 

[Thedude]

I've taken the off plenty of times. I forgot the proper name for them tho. Float bowl. Thanks though!

 

[Paul Sutton]

Thanks MaxPete, will be getting a set! This brand is available in the UK.

 

[MaxPete]

Good for you. They really are very nicely made tools. The larger drivers have a knurled section just below the handle which makes it very easy to spin out long screws quickly.

 

[fredintoon]

Hi Pete,
I blame Henry Ford. He couldn't make a deal with Mr. Robertson so he went with Phillips Heads instead.
Phillips heads were designed to "Cam out" before they stripped out of sheetmetal duct work and were never
meant for assembling things that needed to be dismantled for servicing. Alas that we are stuck with the things.
And while the JIS lookalike may work better when used with the appropriate JIS driver, it's still a bit dodgy.
What I do with every crosspoint screw I remove is throw it away and use an Allen head screw in it's place.

 

[MaxPete]

Not a bad plan Fred - I've done that too. In the meantime, JIS do work OK in most cases.

 

[retiredgentleman]

Right on Fred! I think I have tossed out every JIS on my bike. Wait a minute................OK there may be a few left. For the smaller screws, Allen heads are the only way to fly with these bikes.

Also,I did replace the stator mounting screws, with bolts. Just easier to use a torque wrench.

 

[fredintoon]

Not a bad plan Fred - I've done that too. In the meantime, JIS do work OK in most cases.

Hi Pete,
not "most". Oh no.
The only time that JIS heads work OK is on stuff that ain't been PO'd and then only if you know that the fasteners need JIS drivers.
Working on a used machine where the dreaded PO had cratered out all the JIS fasteners so that the only way to remove them is to gash them across
with a cutting wheel in a Dremel tool to use a blade screwdriver on them is another story.
I bought my bike new long before I learned it's screw heads weren't Phillips or that JIS heads even existed.
The extreme care needed to remove the bike's JIS screws with Phillips drivers led me to think "Screw this for a game of cowboys" and do the Allen swap.
I first learned to hate Phillips heads back in the late 1950s working on Triumph Tiger Cubs.
The Cub used them all over the place and they'd crater out for a pastime AND they were mostly down counterbores so you couldn't slot them.
We reckoned the cheap bastards made those fasteners from free-cutting steel (it's about 1% lead so it cuts nice & quick) but perhaps they weren't Phillips heads after all but JIS instead?

 

[fredintoon]

Right on Fred! I think I have tossed out every JIS on my bike. Wait a minute................OK there may be a few left. For the smaller screws, Allen heads are the only way to fly with these bikes.

Also,I did replace the stator mounting screws, with bolts. Just easier to use a torque wrench.

Hi retdgent,
Yeah, my bike is down to the countersunk screws that hold the back halves of the camshaft end cases onto the head.
First and only time I've ever seen a conical locking washer. Wherever would you find one of those if you lost an original?

 

[angus67]

Use a flat star washer and mash it in. I do it when the guys countersink too deep for a counter bolt that is supposed to fit flush after welding