83 GS 450l

[adagre]

Just got my project bike running. It starts nice etc. However I've noticed I have a cracked spark plug wire boot (where it goes onto the plug). Obviously causing it to misfire.

My question is would a non-firing cylinder cause the ever so popular hanging idle? Off choke and when I give it some gas it will climb to 3 or 4k rpm and stay there for awhile or is really slow to return to normal idle.

I also currently only have the headpipes installed as I am installing some aftermarket baffled mufflers (better look). Cut the stock mufflers off.

I also found a large crack in the airbox on the right side (when sitting on the bike). I taped it up to see if it made a difference with the hanging idle but it did not.

I think the carbs are ok but may need cleaning, the choke seems to function normally.

I guess I am wondering if the spark plug wire alone can cause the hanging idle or should I be looking elsewhere? I couldn't see any cracks in the carb boots.

Thanks!

 

[Charlie G]

My guess would be that you have an air leak in your intake somewhere, o-rings, boots , ect.

cg

 

[adagre]

Would the crack in the airbox effect the engine that much? I can see after the carbs being an issue.

Also anyone know of a kit to replace the spark plug boot?

 

[apopleptic]

The airbox on these are designed to be a sealed system. Any openings in it can be bad. Including the missing boots, or cracks, or no foam. even not having the top on the airbox will effect how it runs.

 

[adagre]

I also just realized looking at the parts fiche that I have forgotten to reattach the hose that runs from the valve cover to the airbox. I will try sealing these things up and see how it goes.