Fuel lines & Fuel Flow to the Carbs.

Hi all. Have just installed a fine replacement fuel petcock from Z1 Enterprises onto my LTD tank. I've attached a couple of pics of the set-up and the (clear) fuel lines. This is a single outlet petcock that runs to a fuel filter and then to a brass "T". From the brass T, each fuel line runs to both sides of the carbs. My question, is this: Does it matter if the fuel line (or T-connect) sits slightly above or about even with the level of the fuel intake on the carbs? I assume that it's not strictly a gravity feed thing, but a vacuum feed as well??? I'd appreciate any thoughts or observations on this. In the 1st pic, the t-connect is not shown, but you can see the two fuel lines coming from the t-connect to the carbs. The other pic gives a more complete layout. Thanks.

The other pic.

Skip:
The stock petcock has two outlets, so each fuel line gets full flow from the tank.
Your setup is going to split the fuel flow after it leaves the single-port petcock... will that restrict your fuel flow to the carbs?

Good question. I consulted with Jeff at Z1 who recommended the set-up. I also ran it by wiredgeorge who didn't indicate it would be a problem. My concern was the placement/location of the fuel lines. I hope this isn't an issue. No big deal if it is. I'll get a stock replacement. I just need to know the finer details of fuel flow into the system. If it's strictly gravity feed, then I might have an issue.

The system you have is a gravity feed with a siphoning effect potential, not a true vacuum system. Your system will flow but I'd avoid any lower that bowl level loops. Ideally you would have all of the hoses coming to each carb from above to assure equal supply pressure. Also trying to keep the fuel lines as short as possible and equal length from each split or "T" would be nice too. The clear tubing you used seems to have a very thick sidewall, what is the OD?

I'd be interested in knowing your experience with the clear fuel lines as far as how long before they discolor or get hard.

Post edited by: KZ_Rage, at: 2006/05/16 11:42

The OD of the fuel tube is 7/16" with the inner diameter at 1/4". It is a little thicker than I'm used to and it's this thickness that brought about the slightly longer tubing - in that it doesn't bend easily toward a direct placement from the "T". The left-side tube is twice as long as the right side tube coming from the "T" to the carbs. I'm thinking that once the fuel completely runs to the carbs, the length shouldn't matter. But there may be a problem after the fuel is turned off and then is turned on. Initially fuel would go to the rightside carbs 1st since the distance is shorter. This is what I'm worried about. Actually, I'm not sure what to expect, but if need be, I will change to a stock petcock and black fuel tubing if I need to.

I am running the simular set up on my 650 and have been for about 500 miles or so this year.I am running the clear line at equal lenghts after the "T" and I have not had one problem.(knock on wood)I was worried about the supply and sucking the bowls dry and I havent yet.I have made some long hard 100mph runs for a couple 3 miles or so and the lil girl never missed a lick.Just keep the lenghts from the "T" to the carbs equal and you should be good to go.

Thanks rammy. Good to hear that. I went ahead and cut the tubing to equal lengths from the T on my set-up too. Turns out the tubing was just flexible enough.

Skip, Your set up will work fine. On my test bikes, I don't use clear hose but use the ugly black stuff (1/4" ID). I put about an 18" loop in the hose coming off the petcock so I can raise the back of the tank (prop it up using a can) when I sync carbs. When riding, this loop can be well below the level of the carbs with no ill effect. The GRAVITY feed principle is that the TANK (petcock) is higher than the fuel inlets on the carbs. The 1/4" line probably won't flow as much as a 5/16" line which I personally would use on a street bike BUT you really never need to use clamps with 1/4" (I pull the lines all the time). With 5/16" clamps are generally needed.