fuelcock/petcock replacement

[Gorminrider]

I wanted to follow up on the issue of leak after vacuum..........................
.........My observation would be that it is either the luck of the draw or there is something about applying external vacuum that affects the works differently. Could the seating of the diaphram be altered by vacuum force in excess of normal operating levels? I don't know; just throwing that out as a possibility. In any case I would recommend checking after running.even if it is an extra step.
...

Shouldn't be in these simple petcocks designed for gravity...A manifold vacuum gauge is a really useful cheap! tool by the way (air leaks, valves, all that)...usual carb engine is nearabouts 18 to 22 in.-Hg ( about 9 to 11psi reversed as suction, if that's a help.

I can't think how a normal person could install these and somehow and suck the oring in to deformity....

[rphillips]

If you suck on the vacuum side (line), you're unseating the "O" ring, the spring is what seats it when vacuum is gone.

[Gorminrider]

oh, Right! but however, I can't imagine how it's going to be wrecked per dpep's question on the vacuum side of the diaphragm...either the thing is made for an engine, or it's not made right. (barring some design involving pressure control like a fuel pump)

[Gorminrider]

Anyways, thinking a little more about dpep's question... there's obviously quite a lot of pulsation when sampling vacuum at one carb especially at idle, so it's not hard to think that the little o-ring on the plunger would be wiggling in and out (wearing out ?) albeit "lubricated" by fuel somewhat.
Against this idea, a good petcock lasts quite awhile so there must be some damping provided by the spring and the fuel....

[sacruickshank]

Good idea. Do you have more detail on the product--picture or link perhaps? Most of what I saw was threaded and/or too thick to serve the purpose; hence the resort to thicker fuel line. But s proper fitting elbow would for sure be the better option.

https://www.amazon.com/dp/B07CXQR666?psc=1&ref=ppx_yo2ov_dt_b_product_details

[Jonesz]

For you Canucks out there Amazon.ca has a three pack of 5/16 elbows for $13.99 and shipped by Amazon so free with prime or if order totals over 35 bux at:

https://www.amazon.ca/gp/product/B08P1JSXTR/ref=ox_sc_act_title_1?smid=AC9R1W900AN3F&th=1

[dpep]

https://www.amazon.com/dp/B07CXQR666?psc=1&ref=ppx_yo2ov_dt_b_product_details

Would you by chance have a picture of one of these elbows attached to a petcock? I am having a hard time picturing a secure fitting.

[sacruickshank]

Would you by chance have a picture of one of these elbows attached to a petcock? I am having a hard time picturing a secure fitting.

I don't have a pic. I don't try to connect them directly to a petcock, instead I use short pieces of fuel lines to connect the elbows and filters as needed.

[Synthead]

I have one of these on my tank and it works great: https://www.ebay.com/itm/293779800858

[sacruickshank]

Getting back to this thread ... re: the reliability of the cheap Amazon petcocks, mine worked fine until I took the back panel off to move the vacuum port to a better position. Then the fragile membrane tore a little and I now have a gas leak.

Is there an easy DIY fix for the diaphragm? If not, I've already ordered one of the non-vacuum petcocks with 46mm hole spacing and will enlarge mounting holes if needed.

Also, some of the cheapo petcocks have a longish arm that hits the valve cover (on my 550T) when you try to go to RES. I had to dremel it off.

PXL_20220721_104815969.jpg

[93Bandit]

I think you'll have to replace the diaphragm.

There's got to be something we could do to make these Chinese petcocks work. There has to be. If I could get 3 or 4 I have a few ideas to try to see if I can make them work. There has to be a solution...

[grcamna2]

Yeah, I also could not be trusted whatsoever with a manual petcock. My wife had a Honda with one aeons ago, and while I didn't do too bad turning it off (and fortunately it didn't fill the engine with gas if we forgot) neither of us was very good at turning the damn thing on until we tried to pull out onto the busy highway and the engine died...

Anyhoo. Cycle Recycle II downtown (they're about 20-25 minutes from my house) would appear to have petcocks for Don's bike and many others, and in my experience these have worked well.
https://newmotorcycleparts.net/fuel_...cocks_suz.html

Does Cycle-recycle still sell used parts also ?

[sacruickshank]

for posterity, the $20 XS650 46-mm c-c non-vacuum petcock via Amazon had enough slack in the mounting hole size to fit my 44-mm Suzuki mounting holes. I did not have to ream anything out to make room.

I used the rear exit shown in the pic as I didn't trust the the flimsy 90 deg exits fittings

https://www.amazon.com/dp/B07T6T9G7C?psc=1&ref=ppx_yo2ov_dt_b_product_details

[rphillips]

Don't lose that info. Very good for those that need it.

[93Bandit]

for posterity, the $20 XS650 46-mm c-c non-vacuum petcock via Amazon had enough slack in the mounting hole size to fit my 44-mm Suzuki mounting holes. I did not have to ream anything out to make room.

I used the rear exit shown in the pic as I didn't trust the the flimsy 90 deg exits fittings

https://www.amazon.com/dp/B07T6T9G7C...roduct_details

Wow, thanks for sharing! Did you just spin the wheel to decide which one to try? Or did you have one laying around?

I'll be curious to find out if it's any better in quality and functional than the other Chinese petcocks.