Idles fine in the driveway, dies when I take her on the road

[crackerman]

Got a GS650, brand new petcock, all new fuel lines, new plugs, checked the carbs and all are clean, all the o-rings look new. In order to start I need to leave the petcock in the Prime position for 5 minutes before starting. Starts up fine and idles at 12-1300 RPMs. I'm getting vacuum from the carbs and will run in the ON position. Now when I take her on the road in get her up in 4 or 5th gear, when I pull the clutch in to slow down to a stop sign or red light the bike just dies out. I was also on the highway in 5th gear and the bike just cut out on me. Ran some Seafoam through the tank but seems worse. I don't think I have any leaks in the air box or mainfolds. Not sure what to do next?

 

[BassCliff]

Hi,

It sounds like you just need to do it all correctly. Get an O-ring kit from cycleorings.com, get a can of carb dip and properly disassemble and clean the carbs, new intake boots and intake boot o-rings, etc, etc, etc. It's all in your "mega-welcome". I wouldn't steer you wrong.

Thank you for your indulgence,

BassCliff

 

[Steve]

Got a GS650, ..., checked the carbs and all are clean,

Sorry, but you can't tell the carbs are clean by "checking" them. If you don't know the history of the bike, assume they are NOT clean, strip them down and dip them according to the carb cleaning guide found in BassCliff's "Welcome" page.

... In order to start I need to leave the petcock in the Prime position for 5 minutes before starting. ...

Definitely something wrong there. Even when I have rebuilt a set of carbs and put them on the bike DRY, it does not take 5 minutes on PRIME to get enough gas in there to start the bike. If the bike has been run any time in the last week, you should not have to use the PRIME position at all.

... Starts up fine and idles at 12-1300 RPMs. I'm getting vacuum from the carbs and will run in the ON position. Now when I take her on the road in get her up in 4 or 5th gear, when I pull the clutch in to slow down to a stop sign or red light the bike just dies out.

Are you using the "choke" to start the bike? It will raise the idle speed a bit to compensate for the cold engine. It's possible that your idle speed is simply set too low.

... I don't think I have any leaks in the air box or mainfolds. Not sure what to do next?

Don't just "think" that you don't have any leaks, check and VERIFY that you don't have any leaks.

 

[1_v8_merc]

Petcock clog or flow problem?
Even the smallest interruption in fuel flow for a brief period will cause Cut-outs
and stalling.... I've played around with this before while running the tank off of the bike when I was tuning the Fuel/Air mixture, and experimenting with secondary fuel filters.

Also, make sure fuel lines aren't setup TOO horizantally!
I've had problems with my bike not starting up because of this.

Did you check the tank for rust? That'll do it!
Gas cap venting? That can cause stalling.

I have a similar problem on my 650 too.
When I'm slowing down at the bottom of 1st, it cuts out when I squeeze the clutch in.
It turned out that i needed to Up my idle speed a little bit once the bike was fully warmed up. I also played around with the Clucth locknut too.

Also, make sure throttle linkage is working properly, look at the locknuts(2), make sure there's a Slight gap or looseness Where the cable
comes out near the top of the carburetor, but make sure locknuts are secure.
I've tweaked around with that too, and it made my idle work slightly better.

Sounds like you have major cut off problem in the fuel system.....

 

[crackerman]

Petcock clog or flow problem?
Even the smallest interruption in fuel flow for a brief period will cause Cut-outs
and stalling.... I've played around with this before while running the tank off of the bike when I was tuning the Fuel/Air mixture, and experimenting with secondary fuel filters.

Also, make sure fuel lines aren't setup TOO horizantally!
I've had problems with my bike not starting up because of this.

Did you check the tank for rust? That'll do it!
Gas cap venting? That can cause stalling.

I have a similar problem on my 650 too.
When I'm slowing down at the bottom of 1st, it cuts out when I squeeze the clutch in.
It turned out that i needed to Up my idle speed a little bit once the bike was fully warmed up. I also played around with the Clucth locknut too.

Also, make sure throttle linkage is working properly, look at the locknuts(2), make sure there's a Slight gap or looseness Where the cable
comes out near the top of the carburetor, but make sure locknuts are secure.
I've tweaked around with that too, and it made my idle work slightly better.

Sounds like you have major cut off problem in the fuel system.....

Thanks Merc
You've mentioned a few things that I haven't tried. I've replaced the clutch cable so I might just need to play around with the clutch locknut. I keep hearing about gas cap venting. Is there any way to clean the vent or do I need to get a new gas cap. Not realistic to have to take the cap off when I'm at a stop sign. Gas tank looks rust free.

I'm going to do a carb rebuild anyway. Just gotta find the time.

 

[Guest]

Gas Cap

Gas Cap

I took my gas cap apart and cleaned it. I have a 1980 GS1000. If the caps are the same there is alot of stuff in there. Opens up by removing 2 Phillips screws on the underside. Ball bearing and holes to check and clean.

 

[crackerman]

Thanks mike,

I'll check that tonight.

I took my gas cap apart and cleaned it. I have a 1980 GS1000. If the caps are the same there is alot of stuff in there. Opens up by removing 2 Phillips screws on the underside. Ball bearing and holes to check and clean.

 

[crackerman]

Ok dipped the carbs, did the full rebuild with new o-rings. Air box is sealed up right. Carbs looked really good before the dip. Still having issues with die at stop sign or any time I'm come to a stop.

Jacked the idle up to about 2000RPM. It'll kick down to 1500RPMs but is not dieing out right now. Idling high but not stalling out.

 

[Guest]

Get a new petcock
Do a valve adjustment
Good spark?
Check compression

 

[Danjal]

To check your cap just run it in high rpm's for a bit. If it starts stalling pop the cap once you stop and listen for hissing like a vacuum releiving.

Did it just start this problem?

 

[crackerman]

Thanks for the info.

Sold her for $2200. Not bad considering I only paid $500 and maybe put $500 back into her. Going to pick up something newer. Looking for something with EFI. These carbs are a pain in the ass.