You will need to do some research on this. There is a 68 page thread on it here somewhere. It is not exactly a bolt on modification, but it seems to be the way to go. I am interested in it myself. It seems there is enough information out there on it that someone could make a bolt on kit, but it would probably cost more than most people would be willing to pay. Just like the external alternator, this mod seems perfectly suited to the Goldwing, and something it should have come from the factory with.
You are pretty much stuck building your own.Not too hard to do. There is a lot of info on this forum in the ref section and in many other ones on the web. The last one I know of that was making a kit was LDWingnut, but last i heard he went in the hospital and haven't heard any more about him, his website is down I know. Once in a while one of them comes up on Ebay usually between $200 and $300 final bids.
I've completely stopped selling my stuff temporarily.
In any event until I start again, I can say that that there is one other design I like and have made work just fine, and that is the set-up that Silicon Sam runs. Easy to duplicate with plans on here somewhere. Effective and reliable.
My set-up uses coolant to heat the plenum area and heat-transfer from the heads to the tubing runners 90° bend area. Provides for a fully heated manifold which is essential and critical in my experience thus far. I can run a single or dual throat carb with a idle that purrs at 1100 RPM all the way to redline. My tubing runners are unequal length and inconsequental to performance.
My website has been unattended and needs updating, so if you go to it please use it for reference only right now, and loosely at that. I'll update it to reflect something relevant closer to the end of the riding season when I get time to concentrate on it. I'll say now that I plan to continue offering completed manifolds for specific carburetors, but will cease complete kits once my current orders are filled. I'll also provide "parts kits" so you can weld-up your own per my instructions. Other pages on my site, such as the jetting page, will be updated as well to provide accurate jetting points for various carbs. My manual is slow to evolve.
My experience is that NO carb is set-up for our bikes out-of-the-box new and must be jetted then tuned properly.
Where I once had a fair amount of extra time on my hands to devote to this, my time has been prioritized in other more important areas. I'll get it all squared-away over the Winter, but will get the ball rolling again once the riding season starts to die down. Anyone reading this directly involved with me just hang-in there and things will start rolling again.
i have an extra setup, it is the one with the single carb off the 1970 ford mustang 6 cylinder that has the hookup for the throttle cables but is missing the choke cable mount, pm me if interested. i am in the lexington,sc area and have another one on my 83 that you could look at if you wanted to and even make your own. the 83 is not running right now due to ............ lazy ass.... anyways its in the garage and available for you to look at