Carb/fuel lines

Hey guys,

Probably a pretty stupid question but I'm about to replace the spark plugs/wires on my 1982 KZ750N1 and I figured I'd change out some of the hoses because a few of them are starting to show rot. I'm having trouble figuring out what size hoses the bike has for the carbs and fuel lines, I can't find anything in the service manual. I could cut a piece of it off and take it to the auto parts place, but then I'd be out of a mode of transportation until I could get around to fixing it lol. I have attached a few pictures. Thanks for your help!

Typically, the fuel line is 5/16" & the petcock vacuum line is 1/4".
I don't know what size the large valve cover port tubing is.

So all the tubing running out of the carbs is 1/4"?

No. As mentioned, the fuel line is probably 5/16".
There may be a couple of vents, but I don't know what size those are.... you can compare the vent ports to the other ports to figure it out.

The OEM fuel line is metric sized and thin walled. It stretches over the barbed nipple fittings so you don't need a clamp. Auto fuel hose is much thicker, and has a fabric reinforcement inside since it's intended for high pressure applications. You can buy the stretchy metric fuel line from ebay (sold by the foot). I'd go this way before using automotive hose, which will likely require using hose clamps to avoid leaks.

One of the photos shows the hoses for the air injection system. These are totally different. If you need hoses for that I'd go with the OEM stuff, or at least remove the hoses and measure the size carefully.

The original metric fuel lines were very snug, but they did originally use springy clamps. After going through a variety of different fuel lines over the years I have found what I consider to be the best for fit and long term use with modern, ethanol laced fuels. I use Goodyear 5/16" Fuel Hose SAE 30R7 Part # 65123 that I had a Goodyear distributor order for me. This fuel line is a snug fit, but still uses clamps. See www.goodyearep.com/ProductsDetail.aspx?id=10526

I use the spring type clamps shown below - 2 seconds to put on or remove with long nose pliers instead of fighting with a screwdriver in tight spaces.

BTW - I tried Gates Barricade fuel line - it is absolute TRASH. The inner sleeve rolls up like a sloppy sock when you put the hose on the nipple and blocks the fuel flow, and if a piece of that inner sleeve breaks lose it will end up in the carb passages. What crap!
Ed

Agree with those type of spring clamps and been using Goodyear 5/16 inch gas line that I get from Farm and Fleet for a very long time ..... just replaced it last summer after dang too long.

I use 1/4" clear line from Motion Pro for the fuel, it fits snug and I don't use any clamps .
They have been on my bike for 16,000 miles ( two years ) but have gotten hard and it is time to replace them with fresh ones, I bought a long roll.

The vacuum lines are a different size and I forget what I used , something black from an auto parts store,
I got a bunch of samples and went with what fit.

As for the over flows , again I went to an auto parts and found a small yellow fuel line that fit snug.
Bring a sample in with you if you have one.

Don't worry about it being metric as long as it fits snugly and is fuel proof you'll be fine


JD

Nessism wrote: The OEM fuel line is metric sized and thin walled. It stretches over the barbed nipple fittings so you don't need a clamp. ....

The Kaw dealers around here don't carry metric tubing. I use zip ties, but I've been meaning to get some Moose clamps to give those a try.

I'll swing by the auto parts place around here and see if they have any to sell by the foot...it can't be that much, I'll pick up a few feet and see where that takes me. Seems like 5/16" is the way to go, I guess it's not really an exact science lol. There are clamps on there right now, I'll pick up a handful and use them when I install the new hose. Can't hurt, right? I suppose maybe I'll make a whole weekend of it while I'm at it, clean the carbs and maybe petcock, too.

There is some expensive fuel line from Napa that does not harden. I have had it on my bike for a year and it is still just as pliable as the day I put it on. $15/ft but you won't have to replace it every 6 months like you do with the cheap stuff. It's yellow in color. I will get the manufacture name when I get off work.