Hello,

I have a 73 shovelhead with a 44mm Mikuni carburetor.
Drives good, but doesn’t start well. I have to kick for about 30 times before it runs, too much...
When I pull open the gashandle and add some fuel into the carb it runs within 3 kicks. So, it doesn’t get fuel when i want to start.

Now I want to fine tune the carburetor, but I can’t find anything about the air/gas screws and float height. Anyone who knows the original settings of the Mikuni VM44 or knows the problem?

Kind regards,

 

Greetings.

While I do not have a solution to your "hard start" problem I can say that I've seen some very good You Tube videos focused on the Mikuni carburetors.
There are videos that demonstrate normal function, disassembly, cleaning, rejetting, reassembly, adjusting, and fine tuning.

You might gain some insight by checking the videos out and they might (I hope!) help you figure out a solution to your problem.

Ride safe!
Best wishes.

 

I think that is a carb that was used on big single cylinder dirt bikes, guys would use them on Harleys back in the 70`s to replace the Tillotson or Bendix carbs they were having trouble with...

Those big round slide Mikuni carbs don`t have an accelerator pump, I`m thinking that is your starting problem.

My suggestion is to upgrade the carb to something with an accelerator pump, an S&S Super E would be a great choice on that bike.

 

if it is a "VM", yes no pump but that is not an issue. the vm series has a special start circuit (actually still used in the more modern units other than the vm).
the carb MUST be setup correctly or it will not work, a quick look at mikuni site or download the tuning manuel will help.
this circuit is hands off. when the plunger is opened, a air port is opened which draws very rich vapors in the fuel bowl through an emulsion tube which also draws up fuel from the bowl and into the carb behind the slide. if the slide is adjusted too high, the dominate air flow will be through the throat and NOT the start circuit and it drops out. and as mr. dan said, no pump, then no fuel.
if you have mechanical issues where you are compensating by having the slide too high you will have issues.
the vm is a great carb and i like them. before electric foot, it was a life saver when kids would yank on the throttle while parked and you came out later and had to kick start.
so the ? what model.

 

It is a Mikuni VM44-3. From what I've searched it's larger than a stock carb for a 1200 shovel, but is that an issue?
I did a ultrasonic clean to it. 3x primary at the gas handle, 3x kick and he did it. But.. One week later and I can kick it again 30 times...

I bought a new gastank (it's a project) and installed it a few days after the carb cleaning. So it ran a few days with the 'old' tank and I hope there was some dirt in the old tank.
I'm going to do an ultrasonic clean again. Following the manual I found out the small rubber+ring at the fuel/air screw is missing.

 

typically a 38 was for sportsters (900>1000) and the 40 was for the BT (1200). the 44 should be "ok" if dialed in. these old machines had crappy air flow so stock will not see much gains.
since hd only turns one fire cycle per kick, my procedure was, fuel on, enrichen on, two primer kicks, ign on, if it did not start the first, the second would, very rarely it needed a third. on a warm machine, the enrichen circuit was seldom needed.
is this machine still running points?

http://www.mikuni.com/pdf/vmmanual.pdf

 

Yes it have points. Going to do a ultrasonic clean this weekend. Keeps you up to date when I have new information

 

do not rule out the points, often a thorn in the flesh. i went with a compu-fire ign and kept the mechanical advancer. it has never lost a beat since 1975, easier start and the cough back and die syndrome gone, a real bummer for manual foot.