1986 700VFR Leaking mad fuel

Hello, I bought this bike maybe a year ago not running. I got it running after a little bit of tinkering and I rode it almost everyday for about 4 months and then I let it sit for maybe 2 weeks. When I went to start it up then it wouldn't start unless it was over choked and even then wasn't running good and it was also pouring fuel out all over the carbs. So I put it away for the winter. No I am working on it found a broken what I would assume vacuum line which then allowed it to start and run no problem but it is still pouring fuel out of what seems every part of the carburators. I was thinking maybe if these bikes had a fuel pressure regulator of some sorts that could be the reason and the fuel pump is running 100% all the time because of it? I haven't been able to find anything on that though. Any information would be super helpful or a point to a different forum where this problem is discussed.

 

This problem has been discussed many times. But you're hoping it's something easy. It's not.

A likely scenario is that the fuel tube o-rings (that connect the carbs) have failed and/or the float bowl o-rings have failed. And/or your carbs were pretty cruddy on the inside and enough gunk has been stirred up to not allow the float valves to operate properly.

My money is still on the fuel tube and float bowl o-rings. They are now over 35 years old, been exposed to gas the whole time and thousands of heat cycles.

IN ANY CASE, your carbs need a proper going thru. If you have never done V4 carbs, start reading and researching now. Then read some more.

The problem is not your fuel pump.

 

This is unfortunate news. Guess I will be taking the carbs off this week.

 

Reminder:

They come off as one unit. Do not remove the plenum prior to removing from the carb boots.

 

"Never cross the streams!"

 

Indeed! Rook mistake was pulling the plenum to reinstall. Just buy insulators now and save the head ache as well.

 

Cleaning of tank, fuel lines and carburettors and new gaskets. The O-ring degrade over time. I have been through exactly what you describe.

 

Removing the plenum when installing or removing the carburetors from the engine leads directly to this:



Tempted to offer him $50, but he seems like a rather ornery fella.

 

wow

 

If I had a 500 I would give him the $200... well $150

 

What in the ROYAL F happened to that poor bike...

 

How else were they supposed to try and get the carbs out? That made it much easier. Plus the rear valve cover is super easy to take off now too. Don't have to do the secret puzzle twist to clear the frame.

Win-Win.

And Rogue, you thought orange was bad.

 

I take everything I said about orangina back. That 500 needs to be placed on a forklift and dropped on the person that cut the bike up.

 

Wasn't smart enough to just cut the lock off the cable....

 

Is there anyway to finesse the fuel Ts out without splitting the rack?

 

no

I said it wasn't easy.

 

These is a series of Youtube Videos on this by Magnandy (CarbSpa), they're brilliant and a MUST WATCH before you venture into the carbs.

here is part 1, there are many , watch them ALL...TWICE



I will add my 2 cents worth of tips:

1) make sure you have a series of containers, labeled 1 ,2,3, 4 and keep the parts for each carb separate. Note that its helpful to mark the carbs too (1,2,3,4) because as you turn them around and upside down to disassemble, its easy to mix parts up and all of a sudden parts from Carb 1 are in Carb 4's container.
2) take LOTS of pictures before you start and as you go, write down every single step as you do it, regardless of how small. follow the reverse to rebuild them
3) don't force the choke forks off, they come off really easy if you do it the right way, you have to remove the black plastic sleeves first. (watch the vids)
4) do NOT use carb cleaner anywhere near the rubber diaphragms that are atop the slides, they will melt
5) use a JIS screwdriver these screws are not Phillips, if you don't have a JIS, I recommend grinding the wee tip off your Phillips driver or they will cam out and strip the screw heads.
6) buy a good rebuild kit, Billy's Out back does a great kit for these bikes
7) clean the outside of the carbs as best you can before you strip them apart, the less crap thats on them means less chance of crap getting where it shouldn't when you disassemble
8) In most cases it is not necessary to remove the brass butterfly from the carb body for a clean and basic rebuild, so id skip that from the videos
9) when separating the carbs from each other, watch out for flying sync springs, they fall out and fly around easy
10) note that for the fuel/air screw, there is a spring, a washer and a tiny o-ring to be retrieved - if your going to the trouble of doing this you may as well do it all at once
11) its an intimidating process to dismantle , clean and rebuild these but not too bad IF you take your time and are very diligent and methodical **** IF YOU'RE NOT A DILIGENT AND METHODICAL PERSON,...... maybe have someone else do it
12) when re-installing the carbs onto the boots, there are also some good tricks and tips by Magnandy on how to do that, note that its incrementally easier with new/softer boots, rock hard boots will make the install very difficult. You can soften the boots by soaking in wintergreen oil and alcohol solution

 

Those are GREAT notes. Heed them. Watch and read everything twice as he says.

Couple comments:

There is a sequence to remove and install the "choke" linkage without removing the plastic sleeves that doesn't force anything. I've seen people MANGLE and crack the plastic trying to remove them. You have to buy the Starter Valve Set to get it and it's not cheap. I guess I'm just saying be careful with them regardless how you handle it, the plastic is old and brittle. Most of the time I find they don't have to be touched if the action is good and the carbs weren't an absolute disaster to start with. I just spray some WD40 under the boot and cycle them a few times.

All the springs can be removed prior to separating. It is much easier to concentrate on removing each spring (and documenting it's location / orientation) than trying to keep track of them when separating. Backing off the synch screws helps in this too.

A dedicated, large, clean work space that can be left without being disturbed is critical in increasing your chances of success.

Read and watch. Repeat.

 

ALSO:

Money is well spent just sending them to a PRO like Squirrelman if you don't plan on becoming a V4 carb expert. Get them back, install, enjoy.

 

Agreed with everything else everyone has said, one thing I haven’t seen - the fuel tube O-Rings in the kit to replace the ones that are likely leaking on your bike can be hot garbage.

I didn’t have a leak from there, but did after re-assembling. I bought viton o rings from McMaster and have been happy since. The float bowl o rings and other pieces can be worked with.

The 85 VF700F uses 7x2mm - I’m sure someone can advise on what your 86 uses.


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