Can someone tell me the inside diameter of the oil injection hose, the one that goes from the pump to the carb. I'm looking for clear hose, so I can see that there's actually oil in the line, and found one for a snowmobile that is 3mm ID, will this fit? Thanks, Tony

O'Reilly's Auto Parts has translucent weedeater fuel line... not sure of the size... it's tiny... I think it might be 3/32" ID.

They have 1/16", 3/32" and 1/8".... What I did was buy a pack of each.

It's in the Lawn and Garden section... I will see if I can find the package or a piece of it and measure.

Thank you Mark!

I found some factory Yamaha line and it's about 7/64" ID using a drill bit.... which is right in between 3/32" and 1/8".

I don't have any bikes running it so I'm not sure what size I used. Pretty sure it might be the 1/8". So 3mm would probably work just fine.

I'm not sure you gain anything with clear line... if pump quits line is likely to sit there full of oil... If you run out of oil, pump would probably start pumping air... but you can always just oil tank level just as easy or maybe even easier.

Downside of other line is the factory thin wall has these cool little sleeve clamps that provide a nice even leakproof clamping force. Other line will have a larger OD so those factory clamps won't work... but you might be able to find some tiny wire spring clamps that will work? Zip ties don't always work too good... often seals better without a zip tie.... but line might come off easier with no clamp.

I use Tygon hoses on all of my bikes and small engines. You can see through it and it remains flexible. On my DT175E I used 1/8” line to go from the pump to the the carb. Very snug fit. I will eventually put small clamps on the hose ends. Small engine shops are a good source for this line. Expensive though, about $4.00 / ft Cdn. Typically found in this yellow colour. Clear is available too but harder to find and more expensive.

I agree that normally there’s not much to see but on my bike after bleeding the system I would see tiny little bubbles once in a while. Need to chase this down.

Thanks for confirming the 1/8"... I do remember using the 3/32" but it was a very very tight fit... I think I swapped to the 1/8" after that because I was afraid the smaller line might split or something.

Tygon is good stuff.

MP Premium 1/8" Tubing

Thank you all for the replies/suggestions and link. The clear line I found for snowmobiles does come with clamps so that's pretty handy especially since my line that has hardened and someone made is short (story of my life lol), doesn't have any clamps on it.

If anyone is interested here's the link to the stuff on e-bay.

clear oil injection line w/clamps

I tried the yellow Tygon lines, purchased at my local Mower/Chainsaw shop. I used the hose primarily for the same hose you want to use it for. I installed it on a '72 CT2 175, a bike that I rode alot on street and dirt. I didn't use clamps, because the hose fit so snug on both ends.

I want to say about a year after I installed the hose, the fit on the banjo at the cylinder became so loose that oil started to weep. The fit loosened up considerably. I had some of the original Yamaha spring clamps, but they really didn't fit the hose like the genuine Yamaha hose. And, the Tygon hose was so loose at the banjo at this point, I didn't trust it. So I went back to genuine Yamaha hose, and have not another problem like that.

Not sure if the Tygon likes the indirect connection to the heat of a cylinder. Usually these hoses are attaching to plastic fittings like the little filter & priming bowl in the small engine gas tank, and then carburetor connections that don't see cylinder type heat.

DEET has the genuine hose in stock, and the price shipped ain't that much different from Tygon. Might even be less.