Topic: diameter of petcock tube

[andy8190]

can someone tell me the diameter of the petcock reserve tube, i found a dealer online that sells small quantities and mine is broken. They dont have it in mm though but i am thinking i can find a close enough fit in standard size. My bike is a 350f

[andy8190]

anybody today?

[MikeJW]

What year model is your 350? Some of them don't have a tube for reserve; only for the main feed.

[andy8190]

its a 72. I know for sure the tube functions to make the reserve work. I'm referring to the tube that goes up into the tank by the way. that might have been confused.

[MikeJW]

I was going by the fact that looking on 2 different Honda OEM parts sites for a parts breakdown picture of your petcock, they both only show the one main tube.

[andy8190]

yes this is true, I am sorry I believe I explained it wrong. I meant that it works as the reserve by acting as the main fuel supply when the petcock is turned to on, when the fuel level drops below the pipe level the carbs no longer get gas from the tube therefore you have to switch over to reserve. that's why I say it makes the reserve function because if you don't have that tube when you run out of gas there is no functioning reserve.

[Scott S]

 Let me dig around in the garage and get some measurements for you. Do you have a hobby shop in your area? I was able to get a 3 or 4 foot long piece for just a few bucks. I've already repaired two or three petcocks and still have LOTS left over.

[MikeJW]

OK, we're both saying the same things, but in slightly different ways. So, I don't see why the tube sticking up into the tank should be a diferent size for all the different bike models. I'm sure the petcock bodies are somewhat different for different tanks but the tubes should be same or close. The tube on my petcock (cb750K) is 5.6 mm outside diameter and 4.6 mm inside diameter. I can't tell you the overall length. I replaced my tube last year by going down to Hobby Lobby and buying a pkg of brass tubing marked  7/32 "
I cut off what I needed (about 3") and it fit perfectly.
Hope that helps

[Scott S]

 My digital calipers are at my Dad's house, but using the cheap plastic set I get approx. 5.5mm O.D. (maybe a smidge more, but less than 6mm) and about 4mm I.D.
 This tubing is slightly bigger O.D. than what's in the petcock, but just enough that you can spin it between your fingers while holding some sandpaper and grind it down. This gives it a nice, tight "swedge" fit.

[andy8190]

yep that's exactly what I needed, thank you so much

[andy8190]

gonna run by hobby lobby and see what they got and will post back tonight if I need anything or with progress