airbox intake?

[boba]

on my 78 gs550, i had it run a few times, and its very very very hard to get started with the button, kick start is about 5 trys, but wont run long. its like the intake of the pistons hass no suction to it. if i turn it ove and cover the opening to the airbox, should there be some kind of suction there(the air intake under the seat)? i put a clear gas line on an it looks like its not sucking gas from the tank either. yes it has gas, a gallon in it. i have 150 compression in all cylenders, and i have a good spark on 1-4 but nothing on 2-3 till it starts, then 2-3 gradually start fireing.i would like to atleast have it run long enogh to sink the carbs, and check the timming with a lite on all cylenders. and does anyone know where i can get new o-rings for the carbs? i probly need to replace them. because i pertty much guess that im goin to have to take them off again.

[Larry D]

on my 78 gs550, i had it run a few times, and its very very very hard to get started with the button, kick start is about 5 trys, but wont run long. its like the intake of the pistons hass no suction to it. if i turn it ove and cover the opening to the airbox, should there be some kind of suction there(the air intake under the seat)? i put a clear gas line on an it looks like its not sucking gas from the tank either. yes it has gas, a gallon in it. i have 150 compression in all cylenders, and i have a good spark on 1-4 but nothing on 2-3 till it starts, then 2-3 gradually start fireing.i would like to atleast have it run long enogh to sink the carbs, and check the timming with a lite on all cylenders. and does anyone know where i can get new o-rings for the carbs? i probly need to replace them. because i pertty much guess that im goin to have to take them off again.

Here's the orings.

http://www.cycleorings.com/

If you haven't done it, completely disassembling and dipping the carbs until they are squeeky clean is required for any bike that has sat for a period of time. It's one of those things that's gotta be done.

If there's no fuel in the line it'll be hard to start. Perhaps the petcock filter is clogged up. Have you had a good look inside the tank ? Or, perhaps the petcock itself is defective.

[boba]

clear line

yes there is fuel and if i put the petcock in one place it will flow into the line and the other to places it actslike it want so suck the fuel in.

[Larry D]

yes there is fuel and if i put the petcock in one place it will flow into the line and the other to places it actslike it want so suck the fuel in.

Great !
Turn the petcock until the fuel flows. Let it go for a minute or two, until the fuel bowls would be filled. Then start the bike. After it's running switch the petcock to the other position. The vacuum should take over.

As far as airflow. Do you have the bike stock ? Airboxes, filter, etc....

[boba]

vacuum?

yes it is stock, the fuel will flow to the bowls and they fill, but thats about far as it goes i think. i took the plugs out and they were dry, turned it over with my finger over the hole and it didnt feel like it wanted to suck it inside. but it would blow it off and have a little fog mist inside the hole. my piston tops were kinda wet looking,

[BassCliff]

Hi Mr. boba,

CLICK HERE for petcock information.

Follow the links below to help get your bike running again.

***********Quoted from Mr. bwringer************
Every GS850 [and most other models] has (or had) a set of well-known issues that MUST be addressed before you have a solid baseline for further troubleshooting. It's a vintage bike, and it's quite common (as in, every single GS850 I have had contact with) that there are multiple problems that have crept up and slowly gotten worse over the years. It's not like a newer vehicle, where there's generally one problem at a time.

These common issues are:

1. Intake O-rings (install NEW OEM or Viton only - common nitrile O-rings will quickly deteriorate from heat)
2. Intake Boots (install NEW -- these cannot be repaired)
3. Valve clearances (more important than most people think)
4. Carb/airbox boots
5. Airbox sealing
6. Air filter sealing
7. Petcock (install a NEW one)
8. On '79 models, install new points or Dyna electronic ignition (or at least verify that the old points are working correctly)
9. On all models, it's fairly common to have problems with the spark plug caps. These are $3 or $4 each, and often worth replacing if you're keeping the stock coils/wires.
10. Stock exhaust with NO leaks or holes -- good seals at the head and at the junctions underneath.

Carburetor maintenance:

Replace the intake boot o-rings, and possibly the intake boots. Here's the procedure:

http://bwringer.com/gs/intakeorings.html

Here's an overview of what happens with this particular problem:

http://cycleorings.com/intake.html

You'll also want to examine the boots between the carbs and the airbox. There's a good chance these are OK, but check them over.
And finally, if things still aren't exactly right, you'll want to order a set of o-rings for BS carbs from the GS owner's best friend, Robert Barr:
http://cycleorings.com
Once you receive these rare rings of delight, then you'll want to thoroughly clean and rebuild your carburetors. Here are step-by-step instructions that make this simple:
http://thegsresources.com/gs_carbrebuild.htm
*****************End Quote*************


For more information, re-read the mega welcome and my little BikeCliff Website. Keep us informed.


Thank you for your indulgence,


BassCliff