Letting it warm up with the choke or enrichener on may be a mistake - typically that will foul the plugs. I start mine with the choke then after about 1/2 minute i turn off the choke and use the throttle lock.

 

Agree this, I use enrichener only so that I can start, then I keep engine running with throttle.

 

Mispoke guys. I use the enrichner a bit longer than 30 seconds but not until she warms up.
Maybe a minute or two.

 

I agree. I have to use the enricher, and when the engine is cold, I have to leave it on a short time.
pg

 

New to the forum, hoping for some help. I have a '72 Ironhead, kick only, with the Mikuni. I have been searching the forums, but no answer for my problem. The bike runs fine and idles fine with the enrichener on, but if I take it off the enrichener, it dies after about ten seconds or so, longer if it is warm. I cannot run it long with the enrichener on because, well, it runs like the enrichener is on. I have checked and rechecked pushrods, checked all numbers on jets and needle, needle in middle position, soaked in carb cleaner and blown out passages with carb cleaner. The bike is slightly overbored (.030), no headwork or stroker, P cams, but really open, short pipes. Any thoughts?

 

I can only think of a couple things you could do.
First is clean the carb better than you did before. This is not meant to be critical, it is just because the carb passages need to be really clean.
The Mikuni is really a bullet proof carb and gives little, if any problems.
The other possibility is if you are using a fuel filter and it is clogged. If you are using a filter then I suggest you replace it with a new one and see if that solves the problem.
That is about all I can think of now.
pg

 

As PG wrote if you have filter check it, most automotive filters (paper element) DO NOT FIT for bike use... they might work when they are new but... they don't flow enough without fuelpump. Also it would be good idea to check filter inside petcock.

 

No inline filter. The one on petcock is good. Also, the plugs are quite wet after it is running. It now is taking about 7 - 10 kicks to start where it only took about 2 or 3 before. When using the rubber manifold adapter (flange to spigot), do I need to use the gasket between them or let the rubber do the sealing? I currently have the gasket in, but it seems like a good spot for a vacuum leak.

 

Are you using:
The original intake manifold?
The metal adapter (bolted to the manifold)?
The rubber boot between the adapter and the carb?

If the answer is 3 yes(s),then you do need to use a gasket between the inlet manifold and the adapter piece.

It should take you 2 kicks at most to start the engine with a VM38 installed. You seem to indicate that the machine once did that.
A Mikuni always needs the enricher to start the machine (even if it has warmed up) but the enricher goes off after the bike starts.

If I have this correct...... You say you have to run the bike with the enricher on?
Well, that is the reason for the wet plugs, but not the problem.
You have either put something back together incorrectly or failed to completely clean the passages pertaining to the enricher.

What have you done to the carb since the days when it was a 1 or 2 kick machine?
pg

 

I am trying to post pictures but no luck. Ok, I have an aluminum intake manifold that attaches to the heads with the bands and clamps. Then, I have the rubber spigot adapter bolted onto that (flange style intake like for an S&S) and the carb is clamped into that. Between the metal intake and the rubber adapter is where the gasket is.
For the kicks, I will give a little history. This bike was found in boxes in a shed, the carb was in one. I completely rebuilt everything in the motor. When I first got it to run, it was about fifty kicks. I adjusted the pushrods, per instructions found here, and it started in one or two kicks. Then, it would die when I turned the enrichener off (up position, plunger down) after about five seconds or so. I took the carb off and soaked it, blew out all of the passages and reassembled. Ran better than before, but still not with the enrichener off. The bike has slowly become more and more kicks to start. I have to give it at least quarter throttle or more or it will not start. It pops out the carb quite often as well. I just checked the timing this morning and it seems right on. The method I am using for timing is bring number one (one dot on flywheel) to center of hole, turn on ignition and rotate advance weights with circuit light on coil to see if it lights up.
Tomorrow, I am going to check pushrods again.