GS500F Carbs

[Kookas]

Hi,

Anyone have a diagram, video or other aid for these carbs? There's a whole lot more going on here than with the older model in all the tutorials I can find. To be specific:

There's this huge hose going from the airbox to a metal cylinder on the left-hand-side of the frame, for example - what is this? The cylinder had two other hoses sticking out the bottom. I thought it might be a pump for the oil-cooler.

And there were two open-ended hoses coming from the carb, one going down next to the airbox overflow, obviously the carb overflow, but then another routed over the airbox, what is that hose for?

In addition, there is a black cylinder mounted on the right-hand-side of the frame with a tiny hose going to a white T that connects from there to a gold-coloured bit on each carb.

All in all, a routing nightmare, not looking forward to trying to get this back on!

[Kookas]

Oh wait, the open-ended hose from the carbs was the water drain hose going to the tank.

[mr72]

the sticky thread has broken photo links in it.

IDK what those parts are you are asking about but they aren't really part of the carbs. They are some kind of emissions stuff, most likely.

[Kookas]

So, a Google for GS500 emissions brings up "secondary air injection". This was apparently added to 2001-onwards GS500s and explains the left-hand cylinder attached to the airbox. It's a device which pumps air from the airbox into the exhaust, hence the two hoses attached to the underside of the cylinder - one hose per exhaust. (In doing so it provides more oxygen for the exhaust gases to combust and reduce emissions.)

The black right-hand frame-mounted cylinder attached to the carb is a vacuum chamber, according to this diagram on BikeBandit (it's part #74). The other open-ended hose coming from the carburetor and running over the top of the airbox is actually the carburetor vent hose, which I knew existed but I thought that was actually the "second air-intake" sticking out of the carb facing to the right.

Now to get these damn float bowl screws off..

[J_Walker]

once you get the bowl screws out, replace them with a allen headed bolt from the hardware store. makes life wonderful after the fact, needle nosed vicegrips help get them out sometimes too, they're just really soft. some will say use the "jis" screw driver heads but while they help, take em apart enough and they get warn, the metal is just too soft.

[Kookas]

once you get the bowl screws out, replace them with a allen headed bolt from the hardware store. makes life wonderful after the fact, needle nosed vicegrips help get them out sometimes too, they're just really soft. some will say use the "jis" screw driver heads but while they help, take em apart enough and they get warn, the metal is just too soft.

Funnily enough I had just ordered myself a pair of vice grips and some proper M4 allen-head bolts! These screws are made of cheese, and since a couple are already rounded-off and needing replacement I may as well order myself some proper allen-heads and chuck the lot of them before the rest follow suit.

[Kookas]

Got to wonder, am I just clumsy or do the fuel hose clamps do more harm than good? A couple of weeks back whilst taking off the tank, the reserve hose sheared at the tank, and then today the main hose did too. They both sheared off right where the hose clamp held them onto the tank nipples. I never had this issue on my older GS, which had much cheaper, but blunter, hose clamps that were basically just thin bits of wire wrapped around the hose like a C-clip. In fact I had to use the hoses off the old GS to replace the sheared ones from the newer one! I haven't got anything else so I've decided to just leave both fuel hoses without any clamps, they're on well past the nipple barbs anyway so no reason they'd come off or leak in an unpressurised system like this.

[ajensen]

If the fuel line is a tight push fit, I do not use clamps. I have not had any trouble, but I'd like to hear from others.

[Kookas]

If the fuel line is a tight push fit, I do not use clamps. I have not had any trouble, but I'd like to hear from others.

I've already had the reserve line with no clamps on the tank for at least a few hundred miles, had no issues whatsoever. It's also only half-way up the petcock nipple, because God only knows why they thought it was a great idea to make the petcock nipples several mills bigger than the tank ones on the newer bikes. Mind you, I have ordered some new fuel hose and hope I'll be able to get that all the way on after I've heated it up a bit! But to be honest, it's pretty hard trying to get the hoses back off there even though they aren't "fully" on, there's no way they're ever just going to randomly decide to pop off. Still, looks kind of ugly so I want to see if I can do a better job of it with a hair dryer to heat up the petcock end of the new hoses when I get them.

[J_Walker]

with new non-OEM lines [thicker walls] I just shaved one of the fuel lines with a razor blade at the tank petcock. maybe this time around I'll get around to replacing the brass nipples [they are just friction fit in there..] with some brass tubing of the same size. but longer and slightly flared out.

[Kookas]

I've just replaced both fuel lines with this:

https://www.advancedfluidsolutions.co.uk/8mm-id-516-saej30r6-rubber-petroldiesel-fuel-line-hose-610-p.asp

Nothing too singin' and dancin', just standard 8mm rubber hose (although the walls are slightly thicker than the OEM lines). Heated up the petcock end with a hairdryer and it fitted perfectly to both tank and petcock, without the weird sideways deformation I got with the old 7mm rubber I fitted cold. Pretty snug on the petcock, no need for a clamp there. Takes a good effort to take it off the tank end so no need for it there either! I sort of suspect the hose clamps were more there to prevent fuel leaks, but as long as the barbs are wider than the internal diameter of the hose I can't see that happening.