1985 40 hp internal fuel lines?

[pcrussell50]

3-cylinder 3-carbs...

Anyway, The under-carb fuel lines in the Yammie 40 are all kind of hard. And I don't know if they are even alcohol safe, even though the motor has run well over the last few years. So I go to one of the parts house web sites and all the part numbers are available. BUT nothing is said at all about the size/diameter of the the hose that is used. I know I can order the factory Yamaha, pre-cut parts. But I'm just as happy to cut my own off a roll of bulk fuel hose. But I don't know what to order. I also don't know if I need to order something metric. But I imagine that with elastomeric fuel hose, it doesn't matter much.

Being a small motor, for under-the-cowl fuel lines, this does not use the stiff braided fuel line connecting the carbs like say, a V6 Merc. But rather much smaller diameter fuel line. Looks like you could almost use Tygon like you might for the cylinder bleed lines in a v6 Merc. Or some other clear fuel line like you might use for a lawn mower, weed wacker or chainsaw.

So, do I go ahead and order expensive, pre-cut factory fuel hose? Or cut my own? (But if I cut my own, I don't know what to order)

-Peter

[Dave S]

If it ani't Broke leave it... or TYGON.......

[pcrussell50]

If it ani't Broke leave it... or TYGON.......

I worry about brittleness and the potential to develop air leaks in rubber lines that have become stiff and hard, even if they still work. Is this a legitimate worry?

-Peter

[25two.stroke]

I mean...you'll see a leak at idle if you got a good fuel pump cause it will pump more than it uses. If none of the lines are wet I wouldn't worry about it. Unless you are takin your carbs off all the time or got your hands messing with the lines, then it won't matter that they are hard.

If you were going to replace them than I would not ever get the pre-made ones. Yamaha is probably 1/4" i.d. and I get this black line that's solid all the way through with no liner. I get it from sierra in 100' rolls, but I have seen the same stuff at o'reillys and motorcycle shops. I am not a fan of any of the modern fuel lines with liners, like the quicksilver silver stuff. Even though it says it is alcohol/modern gas safe, it is not and that liner de-laminates. Tygon as mentioned above is a good option if you can find it in your size and if it is important that the line be transparent. I don't like it because it can be too soft, so I don't use it unless its gotta be transparent.

[pcrussell50]

...Yamaha is probably 1/4" i.d. and I get this black line that's solid all the way through with no liner. I get it from sierra in 100' rolls, but I have seen the same stuff at o'reillys and motorcycle shops.

Do you have a part number? I can't seem to find 1/4 ID Sierra line that is black and solid. Sierra does make some clear yellow 1/4 fuel line. And it's not cheap so it looks legit compared to the cheap stuff. I might end up using that.

-Peter

[25two.stroke]

I go to the shop once a week typically (Saturdays) so I could get you the p/n then if you wanna wait that long...

[pcrussell50]

I go to the shop once a week typically (Saturdays) so I could get you the p/n then if you wanna wait that long...

No hurry. Happy to wait. Thanks, mate.

-Peter

[pcrussell50]

Changing course here...

Is there any reason not to use 1/4" fuel line for the run from the six gallon portable tank and primer bulb, to the motor. Thing is, do high quality primer bulbs and fuel tank and connections to the motor exist in 1/4"? Or am I better off with 5/16"? Even for this little 40hp motor?

-Peter