Petcock without a Priming function?

[jukelemon73]

Hi all.

On this 1979 GS1000L, my manual shows a priming function on the petcock.

There is no such thing on mine - just a RES and ON.

I got a whole box of parts with the bike and even the old petcock (not sure if original) only has RES and ON.

Does that sound right?

Is there a way, besides going direct into the carbs, of priming the bowls without cranking/activating the petcock valve?

Thanks!

 

[Gorminrider]

Not sure about yours but some petcocks have a screw that opens prime....That aside, i have a ninja which really doesn't have a prime and is annoying. Apparently ,from the owner'smanual, you're expected to spin the engine a long time to start it when the bike has empty carbs...

But I disconnect the Vacuum line and apply suction from a syringe and it's own piece of hose that suits. i guess taking the end off and on will eventually wear the vacuum line end out..if it's done often-I figure 5 or 10 years I'll have to nip the stretched end off...

I guess you could get a drill and spin the engine (ignition off) too to save wear on the starter and battery.....

 

[jukelemon73]

Thanks

Yeah, I thought about an external vacuum as well.

Just looked deeper into the manual and sure enough, the L did not have the PRI function like others. Odd but... mystery solved.

 

[Gorminrider]

Oh well, It's not a big issue if you ride the bike once a week. i'd struggle on with it if it is working well.

But prime IS pretty handy. Someone here with your exact bike might know of a specific replacement. "specific" because the size and direction of the outlet can be issues let alone the bolt holes themselves...be careful is what I'm saying.

 

[jukelemon73]

understood and thanks

 

[rphillips]

I've never seen a GS pet cock without a Pri. Always hated the "80" kind that had no Res. My Honda CB1100F has no Pri. hated it since I realized it didn't have it. Takes a lot of cranking if bowls are empty. Have learned, when rarely needed, to start & run it on starting fluid for a few seconds saves both batt. & starter.

 

[jukelemon73]

yeah... I dont know why the L did not but the manual explained it under the specific section for the 1000L.

I like the idea of manually applying vacuum. That should do the trick.

 

[rphillips]

Yep, pretty simple on a Suzuki. The Honda has the vacuum shut-off down on top of the carb rack, not much way to get a hose down in there, to manually apply vacuum (or suck on). Wondering if there may be another "L" model pet cock, with a Pri, that may bolt right on?
Also, I've never owned an "L" model, never realized no Pri..

 

[jukelemon73]

Well... good news is it started up just fine

bad news is there is a massive leak at the T and carb to carb fuel lines. Pouring gas.

It is not the float bowl drain... just a generalized leak above. All I can think is its the lines.

How tight should they be? I assumed they would swell after reading some posts on here but not a chance.

They spin/move very very easily.

Interestingly, the carb did not leak in the RES position. Nothing. BUT... it did not run perfect. Maybe 90%

When the petcock was ON, massive leaks BUT ran 100%.

I think the fuel lines are shot. Agree? But cannot figure out why the additional pressure when ON. i woudl have expected the same fuel flow/pressure in both positions.

 

[Big T]

Your 79 should have VM carbs. Post up a pic of your carbs and petcock so we can be sure what we're talking about

 

[jukelemon73]

Hi

I can confirm I do have the VM26 carbs not the mid year switch to CV (I think)

Petcock is original like (I assume either stock or repro) and looks identical to what is in the Service manual under the Ls and what appears to be the original in the old parts box that came with the bike.

Not saying I won't take a pic... just cannot right now

Look identical to these:
https://www.ebay.com/i/174290519868...MI1a65jNv16QIVx0XVCh2BEA6MEAQYAyABEgKeh_D_BwE

appreciate the help!

 

[hillsy]

The fuel line T between carbs 2 and 3 will have an O ring at each end - so will the straight connectors between the other carbs. They are prone to drying out and leaking so I would check them as well.

 

[jukelemon73]

Hi there. An O ring. Are you 100% sure?

On both the stock quad set and the set I bought during the rebuild, neither had any O Rings on any of the fuel fittings.

 

[jukelemon73]

Another thing I noticed...

When I shut the bike off and when the petcock was in the RUN position, still had massive leaks. BUT not in the RES position.

In both cases, I would have thought the auto cock would have shut down the flow since the bike was off/no vacuum would have been applied.

It seemed like more than just what would have been in the short line from tank to carbs but maybe not.

 

[jukelemon73]

Well... closing this thread.

I ran the bike a few more times and the strangest thing... 0 leaks.

Tuned the carbs and took it out for 30 mins or so and it runs like new. Oddest thing.

Those fuel fittings must be designed to swell to tolerance.

I am sure they fail after some time but all is well now.

I ended at 1 turn out on the fuel screws and ~1.75 out on the air screws on a stock/no leak set up up.

Could not be happier minus the crazy uncomfortable handle bars lol. Have a set coming from an E model that should do the trick.

Appreciate the help fellows.