Fuel Filter on VF500

[slowbird]

I'm being told by many bike guys here in my local area that I should put a Fuel filter on my bike.

I tell them that it's not there from Factory and it is not recommended to install one on the bike.

When they ask why....I have no idea the reason why.

Why shouldn't we put a Fuel Filter on the VF500's?

[tinkerinWstuff]

my '85 500 has a factory filter. It mounts on a little tab aft of the fuel pump.

[Jakobi]

Fuel filters on gravity fed fuel systems are generally not recommended as they can cause too much restriction. If you want to use one make sure it is a bronze sintered filter as they are less restrictive than paper filters. This also means they are more porus and will not filter as well. Fuel filters can and should be used on any fuel system that has a pump. '84-'85 VF500F Interceptors have fuel pumps, '86 does not.

-Jake

[tinkerinWstuff]

Fuel filters on gravity fed fuel systems are generally not recommended as they can cause too much restriction. If you want to use one make sure it is a bronze sintered filter as they are less restrictive than paper filters. This also means they are more porus and will not filter as well. Fuel filters can and should be used on any fuel system that has a pump. '84-'85 VF500F Interceptors have fuel pumps, '86 does not.

-Jake

I would say that's about the best explanation right there. I just took a blackberry picture of mine and will have it posted here momentarily. A keen eye might notice that my filter isn't the exact stock replacement but one I found at Checker that was similar enough. I pulled the rubber mount off the stock one and put it on my replacement so it would mount properly to the tab welded that's welded on the frame.

[squirrelman]

Say, Tinki, your coolant overflow tube, which also acts as a breather, is kinked and more or less non-functional in that position. Try rerouting or whatever is needed to make smooth, gradual bends so that right angles are eliminated......

Make sure the overflow tank is filled to somewhere between the lines.

[tinkerinWstuff]

uh yea - I might start by putting a set of carburators and two coil packs back on the bike. And since I just put the radiator back on the frame yesterday, I'll get some coolant in the overflow and route the hose either tonight or tomorrow.

http://vfrworld.com/forums/first-sec...-85-vf500.html

[ErikRock21]

On my '86 VF500 we spliced in two lawn mower filters, one on each fuel line. There were no issues with flow, and they proved to be very cost effective when the gas tank started rusting out.

[Turbocharged314159]

Theres a mesh screen filter on the inside of the tank on my '86 VF500F, are you sure yous doesn't have one? You have to remove the fuel switch/pump to get it out.

For those saying "FUEL PUMP?? What FUEL PUMP?
YES, there IS a fuel pump on the tank. The on/off/reserve switch is also a diaphragm style fuel pump. It uses vacume presure from the #1 cylinder intake to move a diaphragm, which displaces fuel.
Just pointing it out, it is a common misconception that first and second gen bikes don't have fuel pumps.

[tinkerinWstuff]

Theres a mesh screen filter on the inside of the tank on my '86 VF500F, are you sure yous doesn't have one? You have to remove the fuel switch/pump to get it out.

For those saying "FUEL PUMP?? What FUEL PUMP?
YES, there IS a fuel pump on the tank. The on/off/reserve switch is also a diaphragm style fuel pump. It uses vacume presure from the #1 cylinder intake to move a diaphragm, which displaces fuel.
Just pointing it out, it is a common misconception that first and second gen bikes don't have fuel pumps.

Not exactly.

The '86 didn't have a fuel pump, it was gravity feed. Therefore, they did not have a fuel filter either or flow would suffer. They relied only on the carb screens and the screen in the tank.

My photo above (scroll up) shows the 12v fuel pump and filter used on the '84 and '85 500

The diaphram you speak of on the petcock is a safety fuel shutoff. When the engine is running, vacuum moves the diaphram and allows fuel to flow to the engine. If the engine dies, vacuum is lost, and you don't get doused in fuel as you wait for the paramedics to come scrape you off the pavement.

[Turbocharged314159]

Not exactly.

The '86 didn't have a fuel pump, it was gravity feed. Therefore, they did not have a fuel filter either or flow would suffer. They relied only on the carb screens and the screen in the tank.

My photo above (scroll up) shows the 12v fuel pump and filter used on the '84 and '85 500

The diaphram you speak of on the petcock is a safety fuel shutoff. When the engine is running, vacuum moves the diaphram and allows fuel to flow to the engine. If the engine dies, vacuum is lost, and you don't get doused in fuel as you wait for the paramedics to come scrape you off the pavement.

mmmmm, not sure if I agrea with you there. I'd need to do way more research than I'm up to at 12AM, but whether it's a pump or just a shutoff seems unclear.

I was refering to the screen in the tank as a filter of sorts.
It's not great, but it is a filter.



As far as the pump/switch/shutoff goes, I am unsure of it's entire purpose/function.
The vacume line goes to the intake for the #1 cylinder (after the carb), which would mean there is only vacume presure when that cylinder intakes. That would mean the vacume presure would fluctuate on and off. To me (read; IMHO), that sounds like a fuel pump.
I took apart the pump/switch/shutoff, and it looks like a fuel pump inside, but I admit that it would also be effective as a shutoff (any spring-loaded fuel pump of this type would, though).



(cell phone pics, sorry)

A lot of this is just my opinion and what it looks like to me. YMMV

[tinkerinWstuff]

Are you going to make me go photocopy a page out of the clymer?

Think of it this way. For a vacuum operated pump to work with a spring return, the spring would have to be "matched" to the amount of vacuum suction. Kind of like a valve spring, the spring in a theoretical vacuum pump would have to return the diaphram to the closed position in time before vacuum returned to suck it back the other way.

Problem in, the amount of vacuum changes as the engines RPM changes. Therefore, at some point, the spring would be overcome and remain open all the time. If the spring were strong enough to work at high vacuum, the engine would never be able to overcome it at idle.

Same reason the vacuum sliders in the carbs work the way they do, higher engine vacuum, the higher the sliders open up. And in that case, you are talking a lot bigger spring and a lot smaller vacuum orifice.

[invisible cities]

For those saying "FUEL PUMP?? What FUEL PUMP?
YES, there IS a fuel pump on the tank. The on/off/reserve switch is also a diaphragm style fuel pump. It uses vacume presure from the #1 cylinder intake to move a diaphragm, which displaces fuel.
Just pointing it out, it is a common misconception that first and second gen bikes don't have fuel pumps.

A paper type fuel filter and fuel pump was issued on the '84 and '85 model years only. I've attached a parts diagram for reference - these are parts 1 and 4.

As noted, these can be easily removed when switching to a gravity fed system.

The vacuum controlled diaphragm (second attachment) on the fuel petcock is a safety feature - it is not a fuel pump. The diaphragm can be modified (as it is prone to failure with age) to allow for a true on - off petcock, if desired.

The rest of the attachments are of a stock '84/'85 petcock - Part No. 16950-MF2-005

vf500f fuel filter and pump 84 & 85.jpg

vf500f '84 & '85 fuel petcock.jpg

vf500f '84 '85 fuel petcock 1.jpg

Attachment 9973

vf500f '84 '85 fuel petcock 3.jpg

Attachment 9985

[Turbocharged314159]

Ok, I am wrong.
I guess the info I heard about the fuel pump was the misconception, not the other way around.
Oh well, live and learn.