[Chris Garrett]

Had the darn bike running really nice. Started right up, idle nice at 1100, and accelerate well. Now, it runs okay but it won't idle. The rpms go lower and lower until it finally dies. It's like it's running out of gas, and yes, I checked the fuel level and the petcock. I took the screen out fo the petcock and it was clean and the bowl was full. I put a spark plug tester on and both sides are getting spark.

 

[tbpmusic]

. It's like it's running out of gas,

Or running out of battery???? (Always my first check..)

Do the float bowls have gas??
When it happenf, close the petcock and check the float bowls.

 

[Chris Garrett]

The battery is fine and the bowls have gas.

 

[66Sprint]

Check to make sure the idle screws actually allow idle in BOTH carbs...... They CAN be mis-adjusted to one-lung at lower revs and cause the stalls.... The easiest way to check is to deliberately run it on one side by pulling the plug wire on the other.... It should run with the throttle opened a bit, but just barely idle.... Then swap the sides by re-attaching the "off" plug wire and pull the other side wire....same result? ....... whichever way it won't (try to) idle at all is the misadjusted side....

 

[Chris Garrett]

Checked the idle screws. They are fine. The bike cooled down, and when I started it, the idle was perfect. I let it idle for 4-5 minutes and it never missed a beat. But when I took it to the store and came back 10 minutes later, it died out. Seems like it only does it when it's been driven for a while.

 

[krukster86]

I could be way wrong on this, but have you checked the valve clearances? My bike had similar problems and when I had someone take it in for work he said that my valve clearances were way too tight and the problem went away.

 

[Chris Garrett]

Don't know if the valves would need to be adjusted. What do you think Bill? Could they be out of specs already? Man I hate messin' with those valves. The thing is the bike runs great. I just won't idle.

 

[Bird76Mojo]

How many turns out are your air screws?

GB :mrgreen:

 

[Chris Garrett]

I believe 1 to 1 1/2. Not more. Seems funny that the bike was running so well and this happened so suddenly.

 

[tbpmusic]

I suppose it's possible that the valves tightened up since the rebuild - but I kind of doubt it.
Generally tight valves (especially intakes) will cause a runaway idle, similar to when the carbs are out of synch.

Since Chris has replaced his entire ignition system and the battery is strong, I suspect the carbs somehow.
Air mixture screws are typically at about 3/4 turn on a 450, but Chris did go to aftermarket mufflers on this bike.....

Do what Steve said above first, let us know.

 

[tbpmusic]

Seems funny that the bike was running so well and this happened so suddenly.

Very little about these bikes strikes me as funny anymore........
Mostly they're a giant PIA.
You have to like working on them as much (if not more) than riding them.........