1983 GS450E -Need help with No Start/High Idle Issue

[martinwalsh]

Hello,

I am having some problems with my 1983 GS450E that I need some direction on. In a nutshell the problem is this:

The bike will not start on it’s own. It will start after I attempt to push start it several times, or give it ether. Once it does get going, when you give it the slightest bit of throttle it races up to 3500-4000 rpms and just hangs there. You can lower it back down with the idle adjust screw temporarily, but it’ll just race right back up again and hang at 4000 rpms. Eventually, if I ride it a while it ends up fixing itself…I don’t know why.

I’ve taken the carbs off and brought them to a tech who went through, cleaned and adjusted them. I replaced the rubber intake boots as well and reassembled making sure everything was connected correctly. It still does the same thing.

Ignition seems fine…it’s just not pulling gas into the combustion chamber…even with gas in the bowls and the petcock set on prime.

The bike has a little over 10K miles on it. One other note: The left plug has been getting a little fouled with oil and there is a slight leak around the left camshaft cap…but I’ve been told that the compression still should be great enough to have the bike startup.

Any ideas would really help.

Thanks!!
Marty

[Kcwiro]

make sure your throttle cable is not getting hung up somewhere. If you do not have it routed properly it can shift when you turn teh handle bars and it can cause throttling issues.

Hrm... is your petcock working properly? Using Prime setting will make sure your bike is pulling fuel when you are cranking if that is not working I would consider replacing...make sure your fuel line it is not too long and has a loop in it... mine currently is and sometimes fuel needs encouragement to get pulling fuel properly...do you have a inline fuel filter?

[martinwalsh]

Thanks for the response...I made sure the throttle cable was functioning properly.

I don't have an in-line filter and I can see the gas through the line...It's almost like there is no vaccum to pull the gas into the chamber, but once there is vacuum, it creates mega suction and floods the engine with gas and air causing it to race.

I don't know.

I'll probably take the petcock apart this weekend. It is really hard to turn between positions.

[mikluha]

When you lower your idle with the screw let say to 1200 RPM, does it stay there or does it die?

[martinwalsh]

It definitely doesn't die...it usually will stay there until the slightest twist of the throttle causes it to rise back up to 4000. Sometimes it will go back up with no assistance to 4000.

[martinwalsh]

Actually, if I turn it too much it will die, but I usually stop turning when it sounds like its going out, and it just idles where I stop.

[Nessism]

Sounds like a vacuum leak. Did you install new o-rings in the new carb boots? Also, how many turns out are the pilot screws? They should be set to somewhere near 3 turns from lightly seated.

[martinwalsh]

Yes, I installed new o-rings with the boots...everyone I talk to says it's a vacuum leak. I'm just not sure where it could be leaking form. I've tried the wd40 trick with no response.

I'll have to check the pilot screw when I get home.

[Nessism]

Never had much luck the the WD-40 trick, unless it's a gross leak. Couldn’t hurt to try though…