TOPIC:

Just wondering what purpose the rubber tube between the intakes for cyl. 3 and 4 serves. Goes from the vacuum port on 3 over to 4. None of the other ports have a tube, at least on my  bike.

Took me a bit to find you the "correct" answer to your question in the Service Manual.

On the U.S. model there is a Clean Air System which includes reed valves in the cylinder head valve cover, a Vacuum Switch Valve, hoses from the air filter box and a vacuum hose from the #3 and #4 intake runners Item "C" in drawing E14 (see below) to operate the Vacuum Switch Valve. (All of this is covered on page 180 of the Service Manual.) Your bike may have the Vacuum switch valve removed and instead of just blocking off the vacuum ports on #3 and #4, the previous owner probably just installed a connecting vacuum tube to the nipples on #3 and #4. You can just leave it, or better yet, remove the vacuum tube and install vacuum port rubber caps on those 2 vacuum nipples.



 

 

Thanks Kawboy. I had plugged those ports awhile back but always wondered what they were for. Been having some issues lately and trying to figure out what going on. Might have it rectified now and the bike is probably going to be sold today anyway so that'll be the end of that.