Decent Fuel Line???

[Hydraulic Jack]

6mm.

[viclioce]

The problem was two fold. The worm clamps were cutting the line at the petcock, & the floats were out of adjustment. Last time I adjusted the floats, I went in the wrong direction!

We now have fuel flowing properly & no more leaking! Whew! Ordering a bunch of spring clamps and keeping them on hand. And, the packaging for 6mm fuel line & 1/4” fuel Line lists them as the same. So dropped to 3/16” line and heated the ended up to stretch over the petcock & T joints! Victor

[Bill2001]

No. The petcocks and T-fitting take
6mm tubing. 3/16" tubing is 4.78mm.
Too small. 1/4" is correct.

[Hydraulic Jack]

6mm fuel line would be appropriate for 6mm fittings. But the question comes down to available fuel line. If non-metric is all you can find, which do you use?

6mm = 0.236". Quarter inch fuel line should be nominally 0.25" ID. Inside dimensions may or may not match the designation of your fuel line, but if your fuel line is in fact 0.25" ID, that fuel line is actually just a bit too large for a 6mm fitting. The fuel line ID should be approximately the same as the smallest diameter of a barb fitting, not the largest diameter, and should press fit onto the barb such that pulling it off the barb isn't easy to do. Sort of like a Chinese finger cuff, pulling on a properly sized fuel line on a barb fitting causes the line to go snug. If your line is already about the same ID as the largest outside diameter on the barb, it will slip off readily, and you would be relying on the clamp to make it stay and to keep it from leaking.

That is not to say that 3/16" ID line is correct for a 6mm barb, but if the choice is 3/16" or 1/4", I would use the 3/16" because it will be a firm fit on the barb without the clamp. I wouldn't think heat would be necessary to make it fit, but perhaps that depends on what the line is made of and how thick the tube wall is.

I would hope that an improperly adjusted float would not cause fuel to leak from the fuel line above the carb.

[Hydraulic Jack]

And just because it's out there, if you have a Honda shop handy, ask for 5.5mm fuel hose. This is what Honda used back in the day, when Hodaka was still in business. I think you will find it fits the 6mm fittings just fine. It is, however, black, but if you are using a clear fuel filter, you can still see fuel flow.

[viclioce]

No Honda Shop. Suzuki, Kawasaki, Yamaha, KTM & Polaris, so maybe they have 5.5. I’ll check Tuesday when they open.

I did order a foot of the Tygon on eBay in 1/4” just to try it. I’ll be trying it on the Green Road Toad this week as I have time to get to it. It will be nice to here that one finally fire up too.

Hmmm. That reminds me, I didn’t drill the front of the Green Toad’s piston where it lines up with the bridge like I did with the Red Toad. I should pull the cylinder off and do that so it helps keep the exhaust bridge cooler on this bike too!

Thanks! Victor

[Bill2001]

"Honda shop... 5.5mm fuel line."

Don't think they've used that in years shorty. But a Whitworth hose in 28/64" would have a nominal metric ID of 5.78452mm and come in a translucent British Racing Green.

[viclioce]

Interesting. The shop opens tomorrow & I will see what they have in stock.

The 3/16” line did work as long as I heated up the ends to make them expand and slide onto the petcocks. So I don’t need as tight a clamp now. Going to see if they have son 1/4” spring clamps. The auto parts store didn’t. Victor

[Hydraulic Jack]

I don't use spring clamps anymore on the dirt bike. I safety wire the fuel line. It's easy, it doesn't fail, it won't cut the tube unless you are using baling wire, and while having safety wire pliers is nice, it isn't required. I used needle nose pliers for years. Harbor Freight has safety wire cheap.

And, no, Honda hasn't used 5.5mm tube for years, but since lots of folks still have Honda bikes as old as ours, they still stock the tubing.

[Bullfrog]

While tinkering with the Road Toad mentioned in another thread, I checked out the fuel line which had been installed at some point. It measures out at .260"ID and .448"OD - which is kind of odd because I can't find a listing for Tygon fuel tubing 1/4" X 7/16". But this is clearly Tygon tubing - since "Tygon" is printed on the tubing. Enneywayee, with a bit of firm twisting and pushing, this heavy wall Tygon will slide on to the carb fuel fitting on a 50 degree day with no heating of the tubing. The fit IS tight enough that I don't think any kind of securing device is needed at the carb. The tubing slips on to the "T" and the petcocks with only slight expansion of the tubing as it goes on - so a securing wrap (actually, 2 wraps) of safety wire will be used before the machine leaves the garage. If you zoom in on the photo, you can see the slight expansion of the tubing on the tank petcock.

Grab the safety wire ends with pliers (or ViseGrip pliers) and semi-firmly pull while twisting the ends together. Stop twisting when just the slightest (repeat, slightest) indentation of the wire into the tubing is seen. Trim the wire and tuck the sharp end so it won't poke the fuel line or the machine user.

NOTES:
1. The fuel fitting on the Road Toad carb is considerably larger than the fitting on the stock 28mm carb on a Combat Wombat. I use 3/16" X 5/16" Tygon on my 125 enduro bike with CW carb.
2. It doesn't appear to me that one could use the 3/16" ID Tygon on the Road Toad carb - since the tubing would be stretched sooooooo much to fit the inlet fitting that it would likely fail at that point over time.
3. The fuel fitting on the Toad carb measures out at 8mm (.319") between the ribs, while the "T" fitting "barbs" measure out at 6.9mm (.270") (max. OD - no good way to measure between the "ribs") Sorry, I forgot to measure the fuel petcocks.

Ed

[viclioce]

Yep. I just used all 5/16 for the filter to carb connection. The filters I bought are 1/4” in and 5/16” out. I was lucky to find them that way! Bought 4 of them on eVay for $10 shipping included. Victor