1978 GS550 only runs on "pri" setting

[Guest]

I bought and replaced my old notworking petcock. the new one is great, it works well, the only thing i'm concerned about is that the bike only runs on the "pri" setting. I can put it on "on" and it seems to run on just whats left in the carbs.

However, when i put it on "pri" it runs great. It runs like it should, and doesn't bog or do anything wrong.

Is running it on pri going to hurt anything? Or is it an easy fix to get it to run correctly in the on position?

I hope this all makes sense, i find it easier to say things than to type them out haha. Thanks!

[Agemax]

have you connected the vacuum hose from the carbs to the petcock? it will only work on prime if there is no vacuum to open it on "on" or "res"

[DamKevinBoyd]

Yeah, i've got it hooked up. maybe it has a clog in it or something?

[Agemax]

are you sure it is the correct pipe. the vacuum pipe not one of the 2 vent pipes?
is it tight on the ends and no splits in it?

[DamKevinBoyd]

I do believe it's the right one..I'm not entirely sure. When i got the bike it had a vacuum petcock on it...but the back of the petcock had no vacuum nipple. Someone fabbed up a backplate for it. So when i put this new petcock on, i was looking around and found one tucked down into the airbox so i hooked it up. It could very well be the wrong one i suppose. Where should i look to find the right hose?

The one i hooked it to is tight and has no cracks. It comes from in between the 2 carbs on the left side of the bike if you're sitting on it. I think it's carbs 1 and 2.

[Agemax]

that is a vent pipe, you need a pipe that comes off the left side of #3 carb, just under the throttle linkage. (assuming you have VM carbs, i dont know)

[DamKevinBoyd]

Okay sweet! Thanks. I'll go fiddle around and see if i can find it. I'll be back if i get too confused haha.

[DamKevinBoyd]

Okay, so i took the hose from the number 3 carb and put it on. It did the same thing, i have mikuni carbs if that makes any difference.

[Agemax]

can you post a pic of what you have?

[BassCliff]

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Help! Your Bike Won't Start
DON'T DO THESE THINGS
Help! Your Bike Won't Run Well
Oh God! Pods!


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[DamKevinBoyd]

Here's some pictures, i labelled them as best as i could. I hope it makes sense and you can see alright. I've been looking and i don't see any other loose hoses, or any place for another hose to connect to :\ i am confused lol

http://imgur.com/a/50z7C

[DamKevinBoyd]

I should also note that both of those tubes were just hanging, i guess they are vent tubes. I figured one was a vacuum line though.

[Agemax]

ok here is a pic. the 2 blue (wobbly) arrows are the vent tubes, like you have.
the green (wobbly) arrow is where the vacuum pipe joins to the petcock

[subid]

Good lookin' bike

maybe this will help

http://members.dslextreme.com/users/storagecliff/images/hose_locations.html

[DamKevinBoyd]

AH-HA! SUCCESS!

I took the tank off and found the vacuum line. http://imgur.com/a/PhK9M

I took the bike out again and it ran just fine. Thanks a lot for your help and the links! It's very much appreciated.