mikuni carbs on old iron?

[ElekVins]

Hi,

I'm thinking of installing a mikuni VM round side on my 74ci UL...
I'm confused about the correct diameter, between 34, 36 and 38mm?

Seems the 34mm is very popular for the 45ci so I tend to think the 38 would be a good choice for the big twin, but I see a kit which is supposed to fit both engine Vt No: 35-0107 and it confuses me a bit, I know you can change jets but is 34mm enough to feed a UL? Or I should go for a 38mm using adapter VT No: 35-0271 and get a VM38 (doesn't seem to exist a kit)

Did anyone run a mikuni on a big twin flathead?
What was your set up and jets?

[JBinNC]

A 38mm is the size mostly used on pans & shovels. If your intake manifold bore is large enough, that would be what I would use. There used to be 4 screw manifold adapters for the stock pan manifolds and the 38mm carb. Would that fit your existing manifold?

Jim

[ElekVins]

Hi Jim,
Yeah I saw that that's why I'm thinking 38mm should be better as we're talking about the same displacemnt as a FL pan or a Shovel, but then when I read the description of that 34mm kit from V-twin No: 35-0107 and they say it fits UL and WL it brought me doubt.
My manifold is 3 bolts on the UL, not sure of the diameter tho, will have to check that, maybe that will help also.
Did H-D made the 3 bolt manifold in different diameters? (there were oem on UL and WL)

[JBinNC]

Looking at my Palmer's, it looks like the Us and many of the Ws used 1 1/4 Linkerts, and that is approximately 32mm. So that should be sufficient unless you are trying to go fast.

Jim

[flatman]

Actually harley 45s had 3 differrent diameters. The G motors had a small manifold. WLs had bigger manifolds and the WR and WLDR had the biggest.

[ElekVins]

Looking at my Palmer's, it looks like the Us and many of the Ws used 1 1/4 Linkerts, and that is approximately 32mm. So that should be sufficient unless you are trying to go fast.

Jim

Actually harley 45s had 3 differrent diameters. The G motors had a small manifold. WLs had bigger manifolds and the WR and WLDR had the biggest.

Very interesting...
Originally the UL had a M51, does it have a throat of 1"1/4 too?

[JBinNC]

Very interesting...
Originally the UL had a M51, does it have a throat of 1"1/4 too?

Apparently, yes, all the Us.

Jim

[ElekVins]

ok, so the 34mm sounds good enough and the kit makes sense.
I don't plan on racing it lol

Thanks!

[ElekVins]

Well... before ordering a 34mm I mesured the diameter of my intake - couldn't get my caliper between the cylinder so I used a very high tech toothpick... - turns out it's 37mm (1"7/16) so I'm more leaning toward a 38mm carb now...
(plus the hole has a groove at the entrance, which is about 40mm diameter (linkert has that same groove to go in, when the V-twin adapter is flat on that side)

V-twin also sells a kit in 38mm, a Dell'Orto this time (is dell'orto better than mikuni?), who's supposed to fit
G 1937-1963
UL 1937-1948
WL 1937-1952

45ci if you have a WR manifold...

VT No: 35-0059


What you guys think?

[Dragstews]

38mm would be well suited for the U's ...

[ElekVins]

38mm would be well suited for the U's ...

Dell'orto 38mm is on the way...
Will let you know how it goes.

Thanks everybody!

[38ulh]

Get a 3 hole linkert adapter from kiwi indian, use a reversed shovelhead throttle cable. google vm38/9 and buy the carb only , I run one on my 38u.