990 Gas tank vents - which ones to use?

[HellSickle]

I just finished the cannisterectomy on my 990 and I'm puzzling over which vent to keep in use on each tank. There are three on each side.
I read the upper ones in the middle are to equalize pressure between the two sides. Since I'm planning a flappectomy, I think I can cap those ones off. This leaves two - one on the upper front of the tank and one in the middle of the inside.

I'm inclined to only use the ones on the upper front of the tank, T the two sides together and run the final line up above the fuel level before dropping back down. I'm hoping to eliminate the factory issue with not being able to fill the right side all the way full for fear of fuel leaking when on the side stand.

Any thoughts or experiences are appreciated.

[MortimerSickle]

Originally Posted by HellSickle

...

I'm inclined to only use the ones on the upper front of the tank, T the two sides together and run the final line up above the fuel level before dropping back down. I'm hoping to eliminate the factory issue with not being able to fill the right side all the way full for fear of fuel leaking when on the side stand.
...

This does work. Just don't park in the sun with freshly filled tanks. (And, yes I did extend the hose all the way to the bottom.)

Originally Posted by HellSickle

...This leaves two - one on the upper front of the tank and one in the middle of the inside. ...

If you mean the one about centered on the inside wall of the tank, I don't think it is a vent, but rather a drain for splashover from the filler cap. You will want to keep it.

[HellSickle]

Originally Posted by MortimerSickle

This does work. Just don't park in the sun with freshly filled tanks. (And, yes I did extend the hose all the way to the bottom.)




If you mean the one about centered on the inside wall of the tank, I don't think it is a vent, but rather a drain for splashover from the filler cap. You will want to keep it.

Thanks!

[Dusty]

If you are going to fill them to the brim you'll have to put it on the centerstand till you burn out a half a gallon or so. That just the way it is.

On my 07 i did the flappy also but left the cross over in place, wasn't taking any chances of the famous gas shower that plagued some of the older bikes from over pressurizing.. I only take off one side of the crossover, the same one each time and it gets easier after a few removals.

Like mort said the one is a drain for the caps, gas and water will drain out it.

I routed my front vents way up then down as far as you like, i went to the skidplate. I also added a little fuel filter to each vent line mid way down... not shown in this pic but you can get the idea hopefully. I filled my stock tanks all the way to the caps, but i always kept movin till i burned a bit. That was my setup since the first winter and never gave me any problems.

[gefr]

The tanks need to vent properly. The front hoses are responsible for that. No need for extra equalizing hoses, once the front hoses do their job. I once used the transparent hose I saw in the picture. I found it gets soft when the temps rise and then gets kinked where the curves are steep. I used rubber hoses to avoid that happening. I keep OEM setup inside the front covers. Not so complicated and avoid cramped place behind the headlight. Side hoses drain water and fuel spills around the cup as noted previously.
Cheers.