petcock?

[95_civic_lx]

when im ridding it seems like the bike is running out of fuel. I looked @ the filter and its not even half fun, but when i run the bike on prime it seems like it runs alright. but i switch the petcock back to on and it does it again, the idle gets lower until it dies. It started when i removed the petcock hoses to since they were pretty stiff and baked....i dont think i switched one of the hoses and i double checked that the vacuum hose was plugged in. any other suggestions?

[beRto]

when im ridding it seems like the bike is running out of fuel. I looked @ the filter and its not even half fun, but when i run the bike on prime it seems like it runs alright. but i switch the petcock back to on and it does it again, the idle gets lower until it dies. It started when i removed the petcock hoses to since they were pretty stiff and baked....i dont think i switched one of the hoses and i double checked that the vacuum hose was plugged in. any other suggestions?

This is a common problem. The frame-mounted petcock gets old and tends to restrict fuel flow. I fixed this problem on my bike (1995) by replacing the frame mounted petcock with a new OEM one. Search for fuel starvation and you will find lots of related threads.

[ben2go]

Try these.

Eliminate the vacuum operation.I do this mod.PM me for details.
http://gstwins.com/gsboard/index.php?topic=19363.0

Cheap non vacuum operated petcock.
http://gstwins.com/gsboard/index.php?topic=36958.0

[nastynate6695]

i replaced mine with 3 way selector i bought from a boat store for $2 and then bought some house from homedepot for about $3..  i had hose clamps around the house that i used instead of  buying new onew or reusing the compression ones.  No i have on off and reserve and i havent had a problem with it yet.

[trumpetguy]

There is no question that the GS petcock is a weak spot, and sometimes replacement is the only option.  This problem was so severe on my bike that the previous owner rejetted the cars twice and eventually sold the bike in frustration.

I isolated the problem to the petcock and routinely switched to PRIME when riding on the interstate.  Then I happened on to the solution that has served me well for a year and a half --  I adjusted the valves!  Sounds silly, but I had an exhaust valve so tight that engine vacuum was suffering, and the petcock functioned poorly.  With the adjustment, engine vacuum was higher, and the petcock worked MUCH better.  I have gone from having to use the PRIME position every time I am on the interstate to only having to use it in high winds.

I really like having an automatic petcock (the way the engineers at Suzuki designed it!) so I put up with the (now only occasional) hiccups.

[jeremy_nash]

I have a petcock off a 2006 on my 89.  had to make a new bracket for it to drop it below the under-seat fairing, but it was worth it to be able to use reserve again!!

[95_civic_lx]

it seems like every one is switching to the vacuum less petcocks. This would be like having the bike on prime the whole time right? i accidentally did that and fuel was flooding the carbs and was coming out the filters....

[DoD#i]

it seems like every one is switching to the vacuum less petcocks. This would be like having the bike on prime the whole time right? i accidentally did that and fuel was flooding the carbs and was coming out the filters....

The trick is is to make turning it off a part of your shut-down routine, and turning it on a part of your start-up routine (it is, after all, the first item in FINE-C). I'm riding on prime now, since I don't want to tear down and be off the road (though it should only take a day), and I reach down and turn the thing to run (which is "off" as it's presently not working on vacuum) about .3 miles (.5km)  from home. I know how far I can do that because going the other direction, if I forget to turn it on, there's a point where it starts to stumble and needs to be switched to prime...

[ben2go]

The internal orifice that feeds the PRI is half the size of the outlet to the hose.This causes fuel starvation.Not to much on a stock bike but a rejeted bike with a lunch box becomes a major problem at sustained highway speeds.Especially if the bike has 150's.

[95_civic_lx]

i took apart the petcock and the diaphram looked like it was still good...only in the vacuum port there was this tar like substance took about a chunk through the middle hole and a small ball through the vacuum port... cleaned with carb cleaner and will reassemble...will this be the answer to my problem? ill let u guys know how it goes.

[ben2go]

i took apart the petcock and the diaphram looked like it was still good...only in the vacuum port there was this tar like substance took about a chunk through the middle hole and a small ball through the vacuum port... cleaned with carb cleaner and will reassemble...will this be the answer to my problem? ill let u guys know how it goes.

Here's the petcock layout in the order that it goes together.



Here's the diaphram spring that is omitted.I use a small pointed pair of sissors to cut out the diaphram leaving the O-ring and outter gasket.If it leaks from there I use some fuel resistant RTV.It's worked on my black bike for over a year.


This is a pic of the spring that helps seal the plastic cone.Make sure the cone fits really snug in the petcock main body.The spring pushes against the knob at the same time as it pushes the cone into the petcock body.The oring on the knob is to prevent any seepage from making it out of the petcock onto the engine.I soak the O-ring in 2 stroke or regular engine oil.The oil helps the O-ring to swell a little,seal better,and turn a little smoother.



Some people think that the petcock is good because the diaphram looks good.WRONG!This little menace is the small diarphram that holds vacuum when the engine is pulling hard and not producing much vacuum.You can see how this one looks like a little drop of bird crap.It's plugged the little plastic thing with the small hole and will not let vacuum in to the main diaphram.


.

[95_civic_lx]

thats what mine looked like...took quite a bit off that bird crap out. lets see when i assemble it how it works.