1986 Interceptor vf500f1 very serious running issue

The holes in the sides of the pilot tube are air jets to create the fuel emulsion. There is one very tiny hole thru the central axis that is the pilot fuel jet and meters the fuel as it is sucked up from the bowl. You have to verify that it is open to the correct diameter using the guitar string or some other wire of known size. It will never idle correctly if these are even slightly plugged.

Did you check the mixture screws and mixture/transfer ports for debris?

You should normally have to use the choke to start a cold engine.

Open the bowl drain port screws to verify that you have fuel in the bowls, hopefully of equal amounts.

 

In 1986 the VF500 didn't come with a Fuel filter.


Fuel line came off the Petcock and went into a plastic tube that split into two fuel lines into the carbs.

 

If memory serves me correct there are three orifices on your petcock, one for the fuel line (the big one) and then two the same size that a rubber line connects to for vacumn. If you put the tube on the wrong one it could cause your symptoms or if the diaphram in the petcock itself is sticking. if the vacumn line swap doesnt do the trick try claening and reassembling the petcock. this happened a couple of times on my 85 & 86 interceptor 500's.

 

This just makes me mad. I spent literally 2 hours making a fuel filter fit in that little tiny space between the intake box and the valve cover, but that filter isn't even supposed to be there? Well i'm gonna pull this out and hopefully it'll make my fuel flow properly.

Currently there is only one line connected to the petcock, for fuel. I just picked up 3 feet of vacuum line. I'll connect these in a bit and see if that combined with removing the filter solves my problem.


This is so frustrating, but i really appreciate the help guys. I have basically no experience with carbed engines so this is a pretty steep learning curve. But it'll be worth it to have the bike running again.

 

Mine only had the one vacumn line too, so everytime I pulled it off I thought to myself which one does it go on, and once it wouldn't run right I tried the other. Don't forget the petcock if all else fails the holes in those are small and dirt can/will clog them.

 

K so the bike is now idling on its own, but i have to snap the throttle open in order to make it start. I cleaned the top of the gas cap, removed the fuel filter and ran lines as short as i was able to the carbs so the gas could flow easy. Now the vac line issue is coming into play. See below pics for reference.

When i got the bike, there was a plug on (B), (A) was open and (D) had a line connected to it that was plugged with a screw. Now based on what you guys told me and what i saw on the bike i connected (B) to (D) because it seemed like they were supposed to be connected but the line was cut. The bike suddenly wouldn't even turn over. So i pulled the line off at (D) and gas started pouring out of the fitting as well as the line which runs to (B). I shut the gas off and let the fuel drain out. Leaving the line disconnected at (D) i hit the starter and the bike fired right up. I turned the gas on and gas started pouring out of the line connected at (B) again. Since this is a vacuum line i'm assuming this is not normal, or it needs to be connected to somewhere else. I next connected the line from (D) to (A) and started it again. There was no change in the way the bike ran from what i could tell, but when i pulled the line off it started sputtering for a moment then the idle evened out. I also noticed a second fitting on the engine, (C), which has a vacuum when i pull the screw out of it. Should this be connected to the petcock somewhere as well? Or is it supposed to be plugged?

TL;DR

Based on the pic below where should my vacuum lines be connected to? And should there be gas pouring out of (B) when the gas is switched on?

 

Verify the diaphram in the petcock is not stuck. If I read your post correctly in the beginning the bike ran fine all you did was take off the tank to paint it. If this is the case all you did was remove the mounting screws the gas line and vacumn line. Nothing internal on the carbs should have changed (jets being clogged etc) so those should have been left alone. If everything on the carbs was re-assembled correctly you should still only be looking at the gas line vacumn line and possibly the diagphram in the petcock being stuck. Once carbs have been tinkered with there is a chance they may need float levels verified, be synchronized and such.

 

So this is where i'm at now.

[video=youtube;3kQD0n0gAa4]http://www.youtube.com/watch?v=3kQD0n0gAa4[/video]

 

C is a manifold vacuum port. There is one on each cylinder and they are used when synching the carbs.

D is a barb fitting in the manifold vacuum port used to supply vacuum to the large fuel valve diaphragm at A, which is the diaphragm vacuum port that would normally be connected to a vacuum source such as found at D.

B is the air vent for the chamber between the large and small diaphragms.

My guess is that the small internal diaphragm is broken or missing and the previous owner was able to run the valve without the need for vacuum (maybe a 'prime' setting on the valve). Hence the vacuum port from D was plugged, the inlet vacuum port at A was not needed and left open, and B was plugged to keep fuel that was leaking past the torn diaphragm from spilling out.

If the small diaphragm wasn't torn before then it is now that you pulled a vacuum on it thru B.

Buy some diaphragms and rebuild the fuel valve--should be good to go.

A fuel filter is one of the best things you can add to an older bike fuel system to prevent crud from clogging your carbs--go ahead and put it back on--that was not causing your problem.

 

Thanks, thats really helpful. I guess i need to do some work to the diaphragm next.

The problem with the filter is that there really just isnt space for the one i had (or the one that was in there) under the intake box. In order to make it work without kinks i literally had a total of 2 feet of fuel line running around down there. The way it was set up initially there was a massive kink right at the fitting by the petcock. So i'll need to find a shorter one if i'm going to make it work.

 

I have a vacuum line that comes out from the bottom of the bowl on one of the carbs, it has a brading to protect the line from heat etc. does it go on fitting A or B..

pretty positive C and D are both plugged on my bike because they are used for syncronizing the carbs and I don't have any fittings on them. just a fixed screw.

kennyb.. that means then B is just an atmosphere vent tube...
That would leave one line at the front of my tank that would go to the camister filter for Ca. emmissions.
and then A would then hook up to my one left over line coming from the carbs.. correct..

 

With petcock problems, it helps to determine if the diaphram has been modified by removal or alteration cuz a proppa, stock OEM setup may need a little different hose hook-up from a modified one.

 

Yes i think you are correct since "A" is the vacuum port.

 

I installed 2 small sintered bronze filters on my old VF500. It still ran fine.

Have you opened up the Petcock yet to check the Diaphram?

If it's broken...i might have a spare rebuild kit lying around somewhere.

If it still doesn't work...open it up and see take some pics. Make sure the tank is turned so fuel doesn't come gushing out.

 

I found this old thread of mine:

http://vfrworld.com/forums/1st-2nd-generation-1983-1989/16735-help-re-installing-petcock.html

Might help with the line routing and all that jazz.

 

FYI... I bought this bike only as a restoration project. I wanted a bike just to cruse around locally...was unsure of some of the lines when putting the bike back together.. thanks fellas for the insane pics... I think I got it... today I had a problem with the cross over tube with a small leak when adding new fluids, darn...... so I am heli-coiling the bolts and RTV sealing and giving it a try again because one of the bolts is not holding... another little set back... at least I am still under 2,500 with the complete restoration...It's almost as clean as if you bought it new at the dealer... I'll probably sell it when finished.. It did not run when I purchased it, infact, it had been sitting on the side of yard for years...sure... it had one dropped exhaust valve and three other bad ones in the same head when I got into it..... all replaced and lapped and ported...

 

Sounds great!

If you get it running and it runs good....why sell it?

If you ride it....you may just fall in love with it.