Just bought GS425 idling @ 5k

[Guest]

Hello everyone,
I just bought my first motorcycle. A 1979 GS425L. It seems to be in nice shape and starts right up, but it idles at 5k! I tried to clean the carbs today... took them apart and they seemed pretty clean already. I dont think thats the problem and nothing changes when I put them back on the bike. All the lines seem nice and tight. The only thing I found possibly suspect was the air intake on the right side had a small crack near the hose. I tried to cover it with my hand and nothing changed. I tried wd40 on the area and nothing changed. I'm really not sure if thats the problem. I had the air screws at 1 1/2 turns out and tried adjusting them and nothing changed. I tried the idle screw and nothing changed. I am damn near out of ideas, anybody have anything?! I'm desperate!

Thanks in advance!

[Nessism]

You might want to check the newbie mistakes thread linked in my signature and start going down the list.

[chuck hahn]

turn the big knob in the center counter clockwise.

[tkent02]

Throttle cable too tight?

[Big T]

Shag,

The throttle cables should be loose, just a bit
The idle adjuster should be turned until it doesn't touch

The carb sync screws should be near the middle

Those are the mechanical things

Do you have the airbox on the carbs?

Air leak suspected

[chuck hahn]

Choose the appropriate carb rebuild tutorial here...

http://members.dslextreme.com/users/bikecliff/

Get the orings and intake manifold orings here...

http://cycleorings.com/

[chuck hahn]

oil the throttle shafts as well...they do get gummed up and sticky

[mikestp]

When I was repairing a small 400cc Yamaha (XS400) I discovered that a kit I had bought from MikesXS had a needle and seat for the float bowl that would not sit down and seal. They had a small wire hook on the top that would not allow the needle to touch down in the bottom of the seat. I had to pull them apart a half dozen times before I sucked on the gas inlet to see if there was a leak. Lo and behold I was able to pull air easily.

Now all my carb rebuilds include a suck on the gas line to see if the float seats have a good seal on the needles.

The symptoms were: would not idle... would only run above 4000 rpm.

Hope this might help a few out there.

mike...
mikestp@yahoo.com

[shagertymma]

Wow, thanks for all the quick replies guys. I'm certainly not very knowledgable so some suggestions have me a little confused; however, I was just outside trying to find anything suspect and I noticed their is a hose on the bottom of the airbox that wasnt connected to anything. It also had a crack in it. I believe it was not connected when I bought the bike. Anybody know where that goes? it must be a vaccum line? Possible that one of the other lines is connected incorrectly. I'm kind of working on someone elses problem.

That hose is obviously an issue, but I'm wondering if the petcock is hooked up correctly. It is connected to the tank, then from the petcock to the carb, and also from the petcock to the connection by the choke (is that where it gets its vaccum?) or should that airbox line go to the petcock? and if so, where does that choke line go?

Thanks again, can't wait to get it running so I can work on the fun stuff!

[Big T]

You'll need to post up a picture of the connections

The hose on the bottom of the airbox is probably the drain

[shagertymma]

I think you're right. Its got to be the drain, didnt know they had one. Its a learning process. My gut is telling me its running lean. The vac seems tight no leaks, it may be from the small crack on the airbox but seems like 5k is really off for such a small crack in that location? I am thinking the leak is further up, just not sure quite where to look. Imgoing to replace gaskets and O-rings, anyone know where there nay be kits available