Wants to Die at Idle - Where Do I look First

[63-Coupe]

It's an 82 Heritage Special.

Bike ran good this morning on a 30 mile secondary highway trip. Started fine when I left to come home but at idle it runs a little rough and wants to die out. When I pull up to a stop sign for example the engine comes back to idle for a second or two, then the RPM varies a bit, and then it just wants to die out. It will keep running just fine if I keep the idle around 1500 to 2000. It pulls strong, and there does not seem to be a miss at all. It does seem to have a small lag when I roll on the throttle on the higway that I never noticed before.

I am assuming it's a fuel issue but I am not familiar with these carbs or their set up at all. So where do I look first? What are the most likely culprits?

 

[drewpy]

I think you'll might need to tweek the pilot mix screw anti clockwise 1/2 a turn till you get a satisfactory tickover!

 

[leedutcher]

syncronize the carbs....

 

[63-Coupe]

Thanks guys. Got a couple of other commitments for the next couple of days but will start playing with it on the weekend.

 

[Travis]

Could be a chunk of shit in one of the pilot jets.. Maybe change the plugs first since it's easy and cheap. I've chased "carb issues" only to find it was plugs just starting to foul out.

 

[63-Coupe]

Well Travis, looks like you might have hit the nail on the head. Had a few minutse last night so I thought I would take your suggestion and try the quick and easy thing first. Pulled the plugs and they were both black with carbon. Cleaned them up and put them back in. Now it seems to be running fine although I have not had time to take it more than a few miles.

I guess it's time for new plugs and to try to figure out why they carboned up in the first place.

 

[Travis]

Throw in some new plugs and see how long they take to get full of carbon again. Make sure you put the correct plugs back in. Maybe the ones in there were not the correct plugs? Is your bike stock and do you know if your jetting is stock? A rich mixture will foul plugs. If you bike is burning any oil that will affect the plugs too. The choke, which is actually a fuel enrichment circuit, will also foul plugs if left on too much.

 

[63-Coupe]

Thanks for your suggestions Travis.

Picked up some new plugs today. The plugs that were in it are NGK BP7ES, gap was around 30, and as far as I know this bike is bone stock, but who knows for sure on anything this age? Not burning any oil and the choke is used to start it and then is on for less than a minute. I am thinking it may just be running a little rich but I am going to try the new plugs and see what happens. It actually went quite a distance today on the old (Cleaned) plugs and ran well. I think I will throw them in the top box as spares for that "Just in case" situation in the middle of nowhere.