VF500F Carburetor Question

I recent purchased a partially disassembled 85 VF500F and an 84 VF500F that had been sitting for a few years and that I am working on getting ready for the summer. This is also my first foray into the V-fours. I believe the 84 is a standard bike and the 85 is a Cali bike. Anyway, I noticed that the carburetor fuel tubes have Ts in them and that they were not hooked into the carb plate the way the other set I have was.

Here are some pics to illustrate.



Being exposed like this I was concerned that they would be prone to contamination. My plan is to simply cap them off and not worry about it. Does anyone see anything wrong with this? Thanks.

-Jake

 

if those are carb vent lines, then they must be open to atmosphere, not plugged

 

I believe they are. It looks like they bridge the float bowls for the front and rear sets. My theory is that they are routed back into the carb plate as a California emissions requirement. In this case my concern is more with debris or other particles getting in there and fouling something up. Any thoughts?

-Jake

 

no problem.....all carbs have open vent lines because the float bowls need to breathe, and debris is not an issue

 

Can anyone else confirm that these are indeed vents? Would there be any problem with hooking some hose up to them and routing the vent elsewhere?

-Jake

 

(84-86) carbs can be setup differently than 83's.

Later models have:
- front air tube with a single vent
- rear air tube with 2 vents

The front and rear vents are connected under the plenum with a rubber hose (be sure the linkage doesn't touch the hose)

The second vent on the rear tube usually has a "J" shaped rubber hose on it and is vented to the atmosphere. The vent points up and to the rear of the carb rack.

The later models were setup differently as it was discovered that the air pulses through the plenum were affecting the carbs.

CA models ... I have no idea.

 

I only have the two vents as pictured. From what you described it sounds like I shouldn't have a problem with linking the two together with some hose though. Thanks.

-Jake

 

You are going to have a problem. The carbs won't vent if you tie them together.

I would hook them to the carb plenum if you can. Also, these vent tubes can be installed incorrectly (reversed and front installed in rear and vice versa).

 

One of the tubes has been installed backwards. Also, both the holes in the plenum have been blocked off. Would I be okay running separate vent lines?

-Jake

 

If the plenum holes are blocked, I would get a small "T" fuel tube from an auto parts store.

Place the "T" tube under the plenum and run a fuel hose from both front and rear tubes to the "T" in the middle. If the "T"s open vent interferes with any linkages, you should be able to twist it out of the way. The tubes should hold the "T" in place.

This way, both air tubes are still tied together, but now vent. With this setup, water would have a tough time getting into the carbs through the vent tubes.

Your other option is to drill the holes into the plenum where the air tubes go - or get another plenum.

 

It sounds like I should have elaborated on my venting scheme. What I intended to do, and am going to proceed with, was to tie the two vents together with a tee as you have described. These carbs will get rebuilt at some point and when they do I'll fix it so the vents are installed correctly. Thanks.

-Jake

 

So did we come to the conclusion that leaving these vent tubes open to atmosphere, and not tied into the holes in the intake plenum is ok? I just have two rubber hoses coming off the vent tubes on the carb racks and i have them tucked under the intake plenum, is this ok? or should they be put into the plenum?

 

I think either way is fine. I haven't had any issues running my carbs this way and I've come across a few examples of it with other carbs. If you can hook them into the plenum plate I would as I think it looks cleaner. If not then venting them to atmosphere is okay. They key thing here is that they should not be blocked.

-Jake

 

Perfect, thats all i needed to know, thank you!