Fuel problem pretty lost.

[JollyRojer]

So picked this bike up from a friend this summer and he had redone all the fuel hoses that winter trying to solve the problem with no luck. For some reason the bike runs extremely rough on the normal fuel setting but swap it to reserve and it runs much better ( still having an issue at any constant speed over 65 with sputtering and dieing) any ideas on where to start looking this is my first bike so excuse the noob questions

[jestercinti]

So picked this bike up from a friend this summer and he had redone all the fuel hoses that winter trying to solve the problem with no luck. For some reason the bike runs extremely rough on the normal fuel setting but swap it to reserve and it runs much better ( still having an issue at any constant speed over 65 with sputtering and dieing) any ideas on where to start looking this is my first bike so excuse the noob questions

Start with the hose diagram. Since you said that there were hoses replaced, start there. Look for kinks.

Reserve and 'on' are 2 different hoses from the tank to the petcock. From the petcock to the carbs it's 1 hose.

[crzydood17]

Close the Tank Petcock.

Pull off the Main fuel line.

hookup a external tank to the main line.

does it work? No? Continue down. If it does work with no issues clean out the tank petcock and or replace.

If its still studdering, rebuild or replace the side petcock.

You clearly have solid vacuum if it is running on reserve.

if neither of these work. Buy a new bike :p

[Big Rich]

Reserve and Prime don't require vacuum from the carbs like the normal On position. I would guess either the petcock needs repaired / replaced, or there is some type of blockage preventing vacuum from the carbs. 

[mustangGT90210]

Make sure the hoses are routed right. The ON hose goes to the nipple facing the engine, on the outside of the petcock, reserve line goes to the nipple facing away from the engine, and petcock to carb is the nipple facing the engine closer to the center of the bike.

I chased a flooding problem that caused me so much farkling grief, 5 oil changes, a carb cleaning and then a carb rebuild, and it was just that hoses were routed wrong.

Other thing - GS500 has a vacuum operated petcock with a design flaw... it tends to starve the motor of fuel at high RPM in the ON position. I fix this by flipping it to PRI on the interstate and then back to ON when I get off

[crzydood17]

What is the point of prime if reserve is always on also? Reserve should be vacuum just like on.

[ThatOtherGuy]

one thing I did to my fuel lines was put a red cable tie on the rear line coming from the tank which is also the reserve if I understand correctly.  word association, red/rear(/reserve), that way I never reconnect it to the wrong outlet.

you can see the red cable tie in the photo in the right part when I was tuning the carbs.

[craigs449]

one thing I did to my fuel lines was put a red cable tie on the rear line coming from the tank which is also the reserve if I understand correctly.  word association, red/rear(/reserve), that way I never reconnect it to the wrong outlet.

you can see the red cable tie in the photo in the right part when I was tuning the carbs.

off subject, but why do you have a cramp buster on the left grip? 

[ThatOtherGuy]

one thing I did to my fuel lines was put a red cable tie on the rear line coming from the tank which is also the reserve if I understand correctly.  word association, red/rear(/reserve), that way I never reconnect it to the wrong outlet.

you can see the red cable tie in the photo in the right part when I was tuning the carbs.

off subject, but why do you have a cramp buster on the left grip?

to rest my hand on.  have them both sides on both bikes, just comfortable is all, particularly with arthritic problems.

[jestercinti]

Lots of questions regarding fuel chickens.  Here's an explanation in case you all were wondering how it works:

http://wiki.gstwins.com/index.php?n=Upgrades.Petcock

[Paudie M]

Hi lad i agree with Big Rich , sounds like the petcock. Vacuum is needed when using the 'on' position.
I had similiar issues a few weeks ago. My petcock was knackered and the carb vacuum vent t-connector was cracked. The vacuum vent hose was also missing.
New petcock, new vacuum vent t-connector and hose plus carb sync sorted it out.

[Paulcet]

I'm pretty sure the frame petcock is vacuum operated in both ON and RES positions.  Crazydood is right, there would be no reason for separate RES and PRI positions if RES did not use vacuum.