48 Mik mounting options to various S&S intakes

[dave brode]

All,

Option A.
I used a G manifold with a 2 bolt rubber hose clamp adapter before. It worked ok, but seems a bit clunky.

Option B.
S&S has manifolds with the CV/HSR Mik spigot now in various widths. 1.880" diameter snouts at the head, I believe. [good imo]

https://view.publitas.com/ss-cycle/2019-dealer-catalog-61/page/186-187

Option C.

Zippers has an o-ringed adapter for the G or D intakes that the carb fits into. No hose clamp. 

https://www.zippersperformance.com/mikuni-45-48-carb.html

A view of another mik flange that they show. Not sure what the tab is for, but it shows a better view of the O-rings.

https://www.zippersperformance.com/mikuni-manifold-adapter.html

Anyone see a big advantage to the Zippers 2 bolt adapter to 2 bolt intake setup? It seems to me that the stock "U" seal setup would be more forgiving of mis-alignment.

---

Separate topic, but the zippers backing plate does fit nicely over the Mik's inlet. Those adapters that most air cleaners use look like they would screw with the signal to the air bleeds in the throat.

https://www.ebay.com/itm/Zippers-MaxFlow-Twin-Cam-Mikuni-42-45-48-Air-Cleaner-Kit/202540576317?hash=item2f285bee3d:g:uYsAAOSwsa1bdGNT:rk:1:pf:1&frcectupt=true

Thanks.
Dave

p.s. - btw, anyone else dislike the new manifold design? They save a nickel each on alum or what? 

p.p.s. S&S Evo manifolds of various widths that have provision for M.A.P. sensor are plentiful, but it mounts on rear vs front.
[some are drilled, some not - fixable]

[turboprop]

I have done this every which way imaginable.

The S&S manifolds with spigots will work, but will position the Mik very close to the cylinders. So close that the cylinders will have to be cut in order for the carb to clear.

The adapter sold by Zippers (and many others) is alright, but it too has issues, I just forget what they were. I bought one years ago and returned it.

Vulcan Engineering makes the adapter that Zippers and many others sell, but they also manufacture a different type of bolt-on adapter. I use this adapter on my red/white FXR with a TC124. The intake setup on this bike consists of an S&S D intake, S&S ⅜" insulating block, Vulcan Mik48 to D adapter and a Mikuni 48 HSR carb. This works very well and has plenty of clearance between the carb and cylinders. I also think the increased plenum volume of this setup over that of the spigot manifold provides a bit of increase in performance, but I do not have any clinical A-B testing to support my hypothesis.

This is the adapter that I run on the engine in my red/white bike and is currently on the engine in the blue/white project bike.

https://secure.vulcanworks.net/store/Mikuni-Hi-Flo-Carb-Back-HRS-48-to-S-and-S-Super-D.html

[dave brode]

Thank you, turboprop. I now see what the tab is for.

Iirc, I had a little fin clearance issue with my 117", even with the hose clamp adapter on a G manifold. Thanks for reminding me of that.

On a 120" that is a bit milder than your engine, would you use the G manifold, or stick with the bigger D manifold? I wonder if the steeper taper in the adapter for the D might actually help the mix go around the short turn better than with the G intake?

I have heard a number of opinions that the extra plenum volume is a good thing.

Dave




https://secure.vulcanworks.net/store/Carb-Spacers-Adapters/

[turboprop]

You know, I suspect that with the limited space between the cylinders for a manifold, that most engine developers would prefer more plenum space than what the D manifold can provide. This pieces are not expensive. I have G and D manifolds for all of my engine builds and adapters for the Mik 45 and 48 carbs to both manifolds. But I like to tinker. For that mild 120" engine I would probably opt for the D intake and the matching adapter.

Have you considered sending whatever manifold, adapter and carb to a head porter to have everything matched?

[dave brode]

The plenum theory does seem logical.

I feel comfy making the intake match the heads. I'm not sure how much money I'm willing to spend. Although I'm sure that a pro would do better, I may just fix the valve job and do a fluff on the MVA heads that I have. I'm sure it'll make more power than I need.   

Thanks much for the insight! I was all set on the CV style intake.

Dave
 

[TorQuePimp]

A G manifold and the adapter turboprop posted a link to is perfect for your combo

Fluffing the mva heads yourself I'm sure you can do

Valvejob/seat angles are critical on these things

[dave brode]

Thanks for the input, TP. I don't want to muddy the thread on the seat angles and such. Another day, another thread....

[dynaglide]

+1 on the Vulcan racerback adapter.  I've been running one of those for many years to mate a Mik 45 to an S&S E manifold on my Dyna     Works like a champ with none of the potential issues of a spigot adapter (much more solid mount)

[speedzter]

There is another potential issue with the race back adapter.
The Mikuni can be susceptible to fuel aeration from vibration.
I've never experienced that problem, but I've always used the rubber U ring spigot mounting .

[dave brode]

The 48 on my 117 would spew gas out on decel on the dyno.

I've read here to turn the gas off 1/2 mile from where you plan to stop! 

[dynaglide]

that fuel aeration thing was only with the big Mikunis, IIRC, and even then only at the top end.  I'm too lazy to search for the post now, but I remember Bruce/Max/Admiral doing a thread way back when on some internal carb mods to eliminate it.  Maybe he'll chime in here...
I do know that I've not personally experienced it with my Mik 45 on a 95" TC.

edited to add:  here's the thread  https://harleytechtalk.com/htt/index.php?topic=85919.msg974500#msg974500
he machined a piece to shroud the main jet to keep it from sucking aerated fuel.

[speed limit]

No problems with my race back from Tman I use it with a S&S oval port manifold.

[dave brode]

Thanks, dynaglide,

Subject: Vibration induced fuel foaming causing fuel overflow on rubber mounted engined bikes.

Reply #48

https://harleytechtalk.com/htt/index.php?topic=85919.25

dynaglide does not have the issue. Maybe his solid mounted setup helps cancel or change the frequency of the vibrations?

[dave brode]

42 Mik fits CV 40 spigot intake?
45 Mik fits CV44 spigot?
48 Mik is larger, and unique to itself?
[above using thin normal "U" ring]

"Fat" ring allows one size smaller carb on a given intake?