1980 450 surging

[Guest]

I know surging is usually an air leak, so let me give the whole scoop. I just got this bike put back together and had it running great last week. Ran it Thursday through Monday, no issues at all except popping on deceleration, which I believe is an exhaust leak, so I'm waiting on gaskets. Then, Tuesday morning, I go to fire it up. Working great, then as it warmed up in the driveway it started surging up to 3k rpm. Checked it over, found a cracked intake boot. Ordered new ones. Installed them, same problem. Weird part is that if I adjust the idle speed, I can't even get it low enough to die. All the way out it keeps running. Lowest I can get it is 1.5k. I have only bench synced the carbs, and I still need those exhaust gaskets, and the bike needs a valve adjustment. My question is...should I suspect the valve adjustment, or exhaust leak for causing this? Or do I need to check other things in the meantime? Just seemed so weird that Monday it ran great, then Tuesday was an issue. Thanks for any and all help or critiques!

Joe

[tom203]

Redo your bench sync- you should be able to back idle stop screw off till both throttle plates are in sync and are completely closed. Make sure throttle cable has some slack in it. Make sure "choke" isn't open a bit.
get to valve adjustment asap!

[T3nrec]

Waiting on parts to come in. Anyone have any other ideas? Or should this general maintenance take care of it?

[hillsy]

What Tom said - you should be able to back off your idle adjuster til the bike stalls. Check you haven't got a tight throttle / choke cable.

Valves out of spec shouldn't make the motor surge - usually it's the other way.

[T3nrec]

checked throttle cable, should be fine. Choke on the 450 is a lever on the side of the carbs. It also seems to be working fine. I will be able to bench synch them tomorrow night, and double check the throttle cables and choke lever/bar/plungers to make sure they are working well. Are there replaceable parts for the choke plungers on the 450's carbs?

[T3nrec]

I should add, when I add more choke, the engine surges higher. Is that normal?

[tom203]

I should add, when I add more choke, the engine surges higher. Is that normal?

Yes, it adds more mixture, no matter where throttle plates are, so rpms take off.

[T3nrec]

Ok....um...super embarrassed right now...my throttle cable was too tight...that's what was causing the high rpm. Intake boots are replaced now though, and valve adjustment goodies are on their way. And the exhaust gaskets are on their way

[T3nrec]

Anyone know approximate jetting for a 1980 gs450e at sea level?

[T3nrec]

Whoops, with pods and new pipes. Still 2 to 2 exhaust, but new mufflers

[tom203]

Anyone know approximate jetting for a 1980 gs450e at sea level?

Basscliff's knows: sea level? The CV carbs don't care

http://members.dslextreme.com/users/bikecliff/images/carbspec_float_height.html#A01

what kind of pods?

[T3nrec]

Uni foam pods

[T3nrec]

So, this is a 450e. Does that mean the stock pilot was a #40? Or a #45? I'm not sure I am understanding the chart

[T3nrec]

Also, now it seems I am having to run it full choke or it revs high. Seems weird...tried searching, can't figure it out

[T3nrec]

Ok, seems that adjusting the fuel screws fixed the idle. It is working properly now