Slight popping/chuffing at idle

[MasterGuns]

Ok, I have completely gone through the carbs, everything is clean and unobstructed. Even installed new diaphragms. Sync is about as close as I can get it using a carbtune. New plugs even. Yet at idle I am still getting an occassional popping or chuffing (whatever) and if hit hard from idle, it doesn't rev immediately; sort of wants to stammer then rev. What am I missing here? Any advise would be most helpful.

[Neil86]

I would look around for a vacuum leak...

-carbs seated in the intake runners?

-83-85 YICS chambers and hoses tested if still attached

-leaking caps on synch ports

-leaking hose to/or pressure sensor

Edited May 29, 2009 by Neil86

[SapperMedic]

Good post, I am going to do the same thing, because mine still just doesn't feel right

[CdnDave77]

Remove your spark plugs and take a good look at them. Keep them in order so you know which came out of which cylinder. if you can.. take some pictures and post them here so we can take a look.

 

They should tell you a lot.. ie: too rich, too lean, uniformally identical or is one cylinder different. It'll give you a good idea where to go next.

 

Just my two cents.

[GeorgeS]

They only have O-Rings. Even if they look good, or if you replace them, you can still have leaks between manifolds, and heads.

 

Maby lift the manifolds, and apply Sealant. ? Several folks have reported doing this to solve leaks at that point.

[usnmustang]

You didn't mention the mixture screws, did you set them to 2 1/2 out? I had the same issue with my RSTD until I started fiddling with those. The #1 was so leaned out it wasn't firing right. Would sputter at idle and pop. After I did some adjusting, it has settled out nice.

[MiCarl]

Remove your spark plugs and take a good look at them. Keep them in order so you know which came out of which cylinder. if you can.. take some pictures and post them here so we can take a look.

 

They should tell you a lot.. ie: too rich, too lean, uniformally identical or is one cylinder different. It'll give you a good idea where to go next.

 

Just my two cents.

 

If you haven't already you might also want to replace them. Failing plugs can cause this behavior too.

[MasterGuns]

Got it fixed. The problem was "none of the above". By replacing both the spark plugs and wires, all the popping and chuffing I was experiencing has been resolved. And run; runs like a scalded dog. After sitting for 13 years she is finally back up and running strong; all oil leaks fixed (neutral switch, clutch shaft seal, both stator cover gromets and both valve covers gaskets), and of course the usual disassembly and vatting of the carbs. I also changed all the fluids, new battery, replaced the CMS, air cleaner (K&N), all the brake pads. All that is left is replace the tires and take her in for a valve adjustment.

 

Thank you to everyone whose advise was given and well received.

 

The last thing I would like to ask advise on is that whenever I turn her off after operating at normal temp, I can hear the coolant bubbling up into the recovery bottle. This is the 7th lst edition I have owned and none of the others did this. Could it be because the PO removed the thermostat, or the PO to him? What would be the symptoms of no thermostat? I have never run a bike without the thermostat so I really don't what would happen. It is a lot of work to go through just to see if it has been removed; so, if anyone can shed any light on this topic, please do.

 

Thanks

[lonestarmedic]

Long time to warm up.

Temps run low in evening on highway

 

Thermostat laying in bottom of saddle bag!

 

Glad it is running Herb. Cables on the way. Getting all the rest out also.

 

JB

[MasterGuns]

Never thought of that; think I'll go look.

 

 

Long time to warm up.

Temps run low in evening on highway

 

Thermostat laying in bottom of saddle bag!

 

Glad it is running Herb. Cables on the way. Getting all the rest out also.

 

JB