I decided that I better start a new thread here so that I do not hi-jack the OP's other thread regarding the 1970 with starting problems.
Carl, here are 2 pics of my Mikuni backing plate. The first shows the frontside (or element side) of the Branch Flowmetrics air filter backing plate sold by Jerry Branch back in the mid 1970's.



The second pic is of the backside of the plate. I am pointing to the ¼-20 bolt that accepts the carb brace.



You will note that this plate is an aluminum casting. This was done because......one, it is cheap to do, and two, because it has a deep recess that the carb snout goes into. That keeps the air cleaner from sticking way out from the engine and is a fine feature. However it complicates the shape and design of the backing plate, so it's another trade off.
Now this casting can be duplicated out of plate but it will take some time to do it. The backing plate uses the standard Ham Can cover and element as what came on the bike when new.............pg

 

Thats what I would want if I'm going to run the ham can with the mikuni. Are those available anywhere? Ebay maybe?


Did you ever check to see if you could get the parts you need for the mikuni? I'd hate to buy one only to find out that I couldn't get parts for it esp. after they told me I could.

Thanks for posting.

 

Carl......
No, I have not talked with Sudco lately about parts for the VM38 carb. They do not list a phone number at their website.
The number I called to talk to them in 2000 is 213-728-5407.
I do not know if this is still a good working number because it has been 9 years now.
Sudo's website show a VM38 Kit for a Sportster that comes with a K&N air cleaner for $321. I assume this is the one you are looking to buy?
They also list the VM38 carb only for $155 (part #001-040)
Now I would think if they are selling these carbs that they would stock replacement parts for them. However, as I have said, I spoke with them directly in 2000 and Sudco told me the carb was obsolete at that time. ???????What gives?????? They seem to sell the carbs today.
So you may want to give them a call. Hope you can connect directly on the phone, otherwise you can email them.
One good thing about a Mikuni, you buy the carb and you are never going to need parts for it, unless you lose or damage something. I have had mine for 34 years and never had to buy anything for it. Today is will run as good as new if I were to put it on the bike.

Before I ring off here, I almost forgot this......
Whatever VM38 carb you decide to buy, make sure it has the 90° elbow for the throttle cable. This is a must have item to get the throttle cable under a Sportster's gas tank. The new VM38 kits I see Sudco has for sale do not show such an elbow in the illustrations.......pg

 

I "customized" original airbox to fit Mikuni HSR, it isn't so hard to do... also to VM 38
First I improved air flow into filter by cutting all material outside filter mounting "ring" (exept from up, here rain some days). Original airbox takes most air from that small opening located front of airbox.Then I cut out that inside surface that comes against carb. Notice that here you can define how deep or far airbox will stick out from engine.



Then I installed airbox back to the bike, now it's good moment to make extra bracket to support airbox.




Then I cut round plate from steal that fit into that "centerhole" then I cutted opening that fits to carb (use that paper seal as model)



When parts fits nicely I just welded them



Just paint and you are done. Bike looks alike original but has better carb.

 

Gents,

Thanks so much for the help with this. I'm going to fabricate an airbox like shown and get a mikuni on the sporty. There's a swap meet coming up in April, maybe I can pick one up there cheap. No sense in buying that Sudco kit if I'm not going to use the air filter or throttle cable.

Carl

 

Sepixlh..........
Great job on that backing plate! Nice weld too on the rather thin metal. Like I said, 'it can be fabricated with a little work' and you illustrate this well.

Carl.......
There are two things that the kit should have and they are very important..... The intake manifold and the rubber boot that fits the manifold on one end and the carb on the other.
Also, I had mentioned the 90° elbow atop the carb slide. This is also important because there is no other way to route the throttle cable under the tank. The Mikuni VM38 sits up really tall.
So if you are looking to get a carb at a swap meet, look for the manifold and rubber boot connector to go with it.
You can make a backing plate and you can make your own throttle cable with a 90° elbow....... It's just a little more work than finding one you can buy.
Sudco's website seems to indicate that they sell the manifold and the rubber boot, so you may want to contact them about that. Let us know how it goes..........pg

 

I wrote the Barnett boys and they gave gave me this p/n and description of the throttle cable for a mikuni. It has the 90 degree elbow on it too:

P/N 101-31-30901. It has a 6mm x .27 threaded elbow at the carb. and it attaches to the slide. It is straight at the top and has 5" of exposed wire.

From what I can see of the Sudco kit, It uses the stock intake manifold, bolts the adapter to it, then pushes the carb into the rubber boot. I found the adapter/boot part at several places.

So, once I whip up a modified air box for the old ham can, I can get everything else off the shelf and I won't have to run the K&N filter.

 

Carlgrover.........
Great detective work! I have written the p/n number down. That ell is important, as I have said before.
It sounds like you have a good plan there and I know you will like the Mikuni. I agree with you on what the Sudco kit seems to show.......an adapter that bolts to the standard manifold with a boot between the adapter and the carb.
Keep us up to date on your project......... pg

 

jireh cycle has the cable for the mikuni and at a very resonable cost.

 

PG

I just won a complete mikuni carb with a branch intake, backing plate, ham can, throttle cable; the whole nine yards for $71 on ebay.

Is there a gasket that goes inbetween the carb and the branch backing plate? I'm thinking that if there isn't, there probably should be.

Thanks for the help,

Carl