A couple of months ago, I posted about the installation of a pair
of Mikuni carberetors from a Yamaha snowmobile onto my 73 MGB GT. Well,
this weekend, I finished the installation, and actually went for a ride.
I should start by saying that the installation was extremely simple, IMHO
simpler than reinstalling the original set of SU's, considering the
condition of my particular set.
The car seems to run quite well, considering that all I changed as
far as jetting was the main jets. These particular carberetors are from a
Yamaha Phazer snowmobile, and are actually quite crude. They consist of
a sidedraft venturi, a float bowl, and a butterfly valve for a throttle.
The enrichening is accomplished with a cable actuated plunger, and idle
mixture is a fuel screw (as opposed to an air screw) on top of each carb.
That's it. No slides, no needles. Mounting required the fabrication of
some brackets to move the carberetors farther from each other so they
would match the MGB intake manifold. I made these from some old 3/4"
angle steel I had laying around. I also had to make a little piece to
connect the carbs so they would both move when the throttle was applied.
Finally, some universal carberetor boots, which are available at any
snowmobile/motorcycle shop for approx. 6 to 8 dollars, mated the carbs
to the manifold.
Bigger main jets weren't in stock at the local Yamaha dealer, so I
drilled out some jets that I had in my toolbox with a ... umm... sixteenth
inch drill bit. Put it this way, the jets that were in the carbs were
#150 Mikunis, and I drilled them out to the equivalent of maybe (just
eyeballing it) 350's or so. Basically BIG. The car fired right up, I
balnced the butterfly's by sight, tweaked the idle mix a bit, and went for
a drive, that simple.
If anyone is interested in hearing more about this, or how to go about
doing it, feel free to email me.
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