'79 750 Petcock - Replace or Repair?

[crazyramen]

I've got a petcock that only flows gas reliably on prime, and it's time for me to tackle that problem.

The 10 noob mistake posts recommends buying a new one over repairing, but I can't seem to find one with the same port layout as my stock. The cheapo "universal" ones all have the ports coming out towards the rear of the bike. I've also had problems with the cheap ones on other bikes I've had. There's one used on eBay but I figure it's just a matter of time before its 45 year old rubber gives out too.

I'm hoping someone has a success story about rebuilding their petcock or can point me to a link where I can get the proper one for my bike.

Posting a pic of the current state of the bike just cause

 

[slayer61]

Just because nobody else has chimed in yet, I can highly recommend Pingel peacocks. I've had them on a few bikes over the years and the only fault I can find, is that they aren't intuitive... rather than up and down, they operate front to back

good luck with whatever you choose

 

[Big T]

The rubber bits are likely still available from Suzuki

But it sounds like the vacuum diaphragm has failed on yours

There's a poll about rebuilding, low success rate

 

[rphillips]

A week before a response??? what happened??? First I'd replace the vacuum line, a slight vacuum leak may make your orig. not be held open properly in "on" position... Also I've had good luck rebuilding these pet cocks but I've not had your problem. Mine always got to leaking when eng. was off..

 

[crazyramen]

Thanks for the input y'all. The issue was certainly with the vacuum diaphragm, I could hear the leak on it when I bench tested it with a syringe. The vacuum line was already replaced when I got the bike. I'm a fan of the vacuum operated petcocks even if they've got more failure points than regular ones.​ The convenience of not being able to forget to turn it off and flood everything is worth it for me.

I ended up going with the $17 Cheapo on ebay. Seems to be decently well made. It fits and doesn't leak when it doesn't get vacuum. I tore it apart before I installed it and found some filter bits and small pieces of rubber that probably would've clogged the carbs, so I flushed it before I installed it... No issues after a few minutes of running, but I'm waiting on a condenser before I give it a real road test. Also, the diaphragm on this cheap one is definitely thinner than OEM, so I expect that'll be the failure point on these, too. I'll update this post after some time.

The brand is 1PZ here's a link: https://www.ebay.com/itm/267159700031

The output faces the wrong way for my '79, so that might interfere with side panels, but this bike didn't come with any so I'm making custom ones anyways.

edit: looks like it's based on Suzuki P/N: 44300-45370 for '81-'83ish 750s

 

[rphillips]

Looks like, on this one, the back plate can be rotated al least 3 different directions so vacuum port may point whatever direction works best for your bike

 

[crazyramen]

Looks like, on this one, the back plate can be rotated al least 3 different directions so vacuum port may point whatever direction works best for your bike

Kinda. It's got locator pins near two of the screws so it can only be rotated in 180? increments. Also the vacuum is actually in the right direction it's the fuel output that's in a different orientation, but it's nbd for my specific application

 

[lizzywhite45]

I had the same problem on my GS. Mine only worked on prime too. I changed the vacuum line first and that helped a bit. Tried a rebuild kit once, worked for a while but not too long. In the end I put on a Pingel and it’s been solid since. Little pricey but worth it.