Low idle after warmup

[Dwmadsen]

1982 R65
The bike starts, idles, and runs fine for 5-10 minutes at which time it falters at idle and will die without continuously rocking the throttle. Let is sit for 30-45 minutes and it is back to idling just fine…until the 5 minute mark at which time where back to the bike wanting to slowly die.

During the poor idling state, the bike will rev without much issue - getting up to speed is certainly missing the power but nevertheless pulls up to speed.

I set the valves, but given the time “to failure”, I am inclined to think they may need to be checked (may be too tight). To this end, what is the latest and greatest recommended clearances?

[Barry]

1982 R65
The bike starts, idles, and runs fine for 5-10 minutes at which time it falters at idle and will die without continuously rocking the throttle. Let is sit for 30-45 minutes and it is back to idling just fine…until the 5 minute mark at which time where back to the bike wanting to slowly die.

During the poor idling state, the bike will rev without much issue - getting up to speed is certainly missing the power but nevertheless pulls up to speed.

I set the valves, but given the time “to failure”, I am inclined to think they may need to be checked (may be too tight). To this end, what is the latest and greatest recommended clearances?

Possible causes of the idle problem: It's getting too much fuel or not enough.  Not enough might be the fuel cap failing to breath but then it wouldn't rev and get up to speed.  So my money would be on too much fuel due to carbs flooding. When it happens take the bowls off and measure the depth of fuel in the bowl. 

On valve clearances, it's safe to use the running in clearances  which are 10 thou (0.25mm) exhaust and 6 thou  (.15mm) Inlet  but make sure they are tightly set i.e. definitely not more than 10 thou and 6 thou.

[Bob_Roller]

Have performed any work on the carbs ?
Like Barry stated, sounds like a fuel level issue in the carbs .
Check the float adjustment, also the foam floats absorb fuel over time .
Floats should weigh around 12 grams .
I’ve had floats hang up on occasion .
Check the adjustment of the ‘choke’/enrichment cables, make sure they fully close when the choke is fully closed .
Do you have any additional fuel filters installed .
What fuel shut off do you have, Germa has the fuel line at the 6 o’clock position and it has a small plastic filter  under the nut that holds the barbed fitting that has the fuel line on it check it for clogging .
Karcoma fuel tap has the fuel line at the 3 o’clock position .
Usually there is a fine mesh filter in the fuel tank covering the fuel intake tubes check it for clogging .
Take the fuel line off, put a length of fuel line in the fuel tap, turn the tap on and see what kind of fuel flow you have .
As Barry mentioned loosen the fuel cap and see if it has an effect on you issue .

[mpe]

My bike was having strange carburetor issues, replaced the foam floats and the problems disappeared. They soak up fuel over time and lose bouyancy.

[georgesgiralt]

Hello,
To avoid this, I cut the fuel supply a while before arriving at home. This way, the bike stop itself from fuel starvation when entering the garage.
It is then stored with the carbs empty of fuel. That saves the floats.
Just my 2¢