I have a friend with a 2005 carbed Bonneville, and she noticed that a vacuum hose connected to a fitting on top of the intake manifold had rotted and broken apart. From what I've been able to piece together it's part of the secondary air injection, and in all of the parts diagrams I've been able to find they're just capped, there's not a line going to them at all. So two questions: 1) Am I correct that those are what open the reed valves for the SAI circuit? If not, what are they? 2) Assuming it Is part of the SAI, is it OK to just pull the hose off of both sides, cap the fittings on the manifolds, and plug the hose ends? I know there are kits to fully replace everything, but I don't think she wants to go through all of that right now. EDIT: I should probably add that I haven't seen it personally yet, so I don't know where the other end of that line currently goes. I asked her when she mentioned it to me, but she wasn't sure.
That doesn’t look standard. The SAI is in the cylinder head next to the plugs. Those vacuum nipples should simply be capped. I would be curious to see where that ribbed hose goes!
As sprinter said , those studs should be capped ! On early carbureted bikes they are used to "vacuum balance" the carburetors , on later fuel injected bikes they are used by the ECU in conjunction with oxygen sensors in the exhaust headers and temperature sensor and a Mass Air Flow sensor to manage fuel and ignition ! That bike needs serious maintenance ! There is or has been fuel leakage !
As Callumity says,they are vacuum nipples that should be capped and are used to balance the carbs. As for the other ribbed tube,that is part of the SAI ,but it would be worth considering getting rid of the SAI.
Most of the bikes I work on are old Hondas, so I'm familiar with carb balancing. That was actually my first thought for those, but I had/have no idea why there's anything connected or where they're going. I'll report back if I get a chance to lift the tank and see what's going on.
Makes sense but the perished fitting will now make the bike appreciably lean on the LH cylinder and make for lumpy running. Just capping it will be an effective short term fix.
It gets worse...I was just chatting with my friend who owns the bike, and she went out to look at it and found that the port on the right side is already capped. I can't even.