carbs overflowing through vent pipes

I have a vfr750fl 1991 and the carbs are leaking fuel out of the twin vent pipes directly behind and underneath the air box, one pipe vents the front pair and the other the rear pair and fuel is pouring from both when the engine is running, they look more like vacume vents rather than overflows, any ideas?

 

Stuck float needle? Could be some debri got caught and is preventing one or more of them from seating. I have used a long brass punch with a hammer and rapped the offending bowls in the past with some results. Be careful you dont punch too hard as you dont wanna ventilate your bowls with the punch. :smile: anyway if that dont work your gona have to take em off as one unit and have a looksie. I love those carbs with them velocity stacks, what an engineering feat. Have a beer or two while your doing it, makes the work less painful sometimes. Cheers

 

Thanks for the speedy reply, i tried knocking the bowls before but to no avail, so i agree that it seems like a stripdown is next, bit of a pain on the V motor with the limited access, spoke to a main dealer today (thanks Honda Portsmouth) and they suggest the same, oh well time to weild the spanners!!

 

Is your petrol tank clean ???

Rust or dirt in there can get into float needle seat area and hold them open, causing the overflow from the vent tubes.

 

If you haven't cleaned and measured the specs according to the manual of float height and cleaned the needle jets, now would be a good time to do this.

Also remove any jetkit as the needles under the vacuum piston sometimes are ever so slightly short and can jam. Its happened to me and ofcourse they let in a lot more fuel.

You can also try throwing a bunch of bolts in your empty gastank when removed from the bike of course and give a good shake. My tank was pretty clean even for being up here in canada and the strong humidity of the summer. Give a good shake, then remove the gas cap.

Good luck and let us know.

But it sounds like a carb issue, float height or needle as described.
Let me know...

 

Hi there, thanks guys, i agree it looks like a carb strip and needle and seat clean, so thats what i'm going for, had a good tip from a local dealer who suggested re-seating the needle with a bit of solvol autosol metal polish to polish any crud of the seat,
will let you know when its fixed,
Cheers Andy

 

You do not have to strip down all of the carbs!!!

Just remove them. Then remove each float bowl one at a time and install a new float needle ONLY!!! The seat allmost NEVER ever goes bad. It is the rubber float needle tip. As the rubber tip on the float needle ages it gets crushed down and the float needle adjustment changes. As soon as you put in a new float needle it is correct again. You have to look at the float needle rubber tip with a magnifying glass to see the damage. EVEN if you are 20 years old. ALSO Do NOT remove the float bowl gasket. Just put a little Vasaline on it before re installing it on the float bowl.

Make sure to remove the idle jet and look through it and make sure you can see daylight through it!! Do not mess with the float adjustment at all. Do not bend it accidentally either.

You are DONE. Put the carbs back on.

If you just clean the needle seat and reinstall the OLD float needle in the seat you will be doing this job all over again. READ THAT TWICE.

You did not tell us how long this bike had been sitting OR if it had been sitting at all.

 

Yep and get stock Honda replacement parts. I have a set of four float needles waiting for my bikie. My cost was roughly $25.00 a set, so times 4 your looking at a $100.00 give or take. Rust in your tank like Squirrel said will suck and screw up your work. Cheers

 

You can get float needles for $5-6 dollars each.
Bike Bandit .com

 

I didnt want to do the K&L thing on my own bike. The kits came with a bunch of other stuff as well, not just float needles.