78 xs400 stalls at idle when warm

[gordonfi]

You can go as many as 4 before going up a jet size. (pilot) My 82 that is all stock runs perfect at 3 1/2.

I don't know what the actual turn count was the other day, but rode to work, and at noon went to start it. It backfired once, and next I saw the Idle Screw on the motor. I had to loosen the tank so I could screw it in a bit to get it started and go home.

Later, I took the tank off again and at 2 1/2-3 turns adjusted on each side while it was idling for maximum RPM with each adjustment. There seemed to be a sweet spot with each one and that's where I left them. I put some caulking over the holes to prevent ejecting the next time and to hold the adjustments. Caulking is easy to poke out if necessary, but will hold things in place until then. It idles now pretty reliably around 1500 rpm. I'll leave it there until the engine gets worked some more.

 

[xschris]

You should have the carbs with the screws exposed.

 

[gordonfi]

You should have the carbs with the screws exposed.

...and then what happens if one pops out along the road and falls off of the Bike?

I was lucky to find the one that fell out at work and decided that I would not take the chance of it falling off in an uncontrolled environment. If it came out during a ride, I'd be screwed. Why it came out, I'm not sure, but sorry, I can't take the chance of it happening again. I would have preferred to put rubber plugs over the screws but didn't have any so this was a temporary fix to keep all parts on the bike. lol

(I have some rubber grommets that may fit. That would probably work if they're a snug fit).

 

[xschris]

So you have carbs that have the screw recessed in the bodies? Those are 80-82 type carbs. I use a rubber plug for those type.

 

[gordonfi]

So you have carbs that have the screw recessed in the bodies? Those are 80-82 type carbs. I use a rubber plug for those type.

It could be that they've been replaced at some time. Yes, they are on top, recessed. But since I just got it a few months ago and the previous owner wasn't to free with any information, I wouldn't know. Thanks for the advice though. Are the 1979 carbs different? Where are the Idle Mix screws on them?

 

[xschris]

These are the 77-79 carbs. The 80-82 ones that you must have use a o-ring and washer. Make sure you still have them.